Loading...
HomeMy WebLinkAboutCOM 0649.004 2002-2004EVALUATION OF A FOUR WAY STOP AT THE NANI KAILUA DRIVE/KAKALINA STREET INTERSECTION LICENSED PROFESSIONAL ENGINEER No. 3393-C U THIS WORK WAS PREPARED BY ME OR UNDER MY WEERVISION Expiration Date: 4/30/04 LO M&E Pacific, Inc. 100 Pauahi Street, Suite 212 Hilo, Hawaii 96720 Telephone: (808)961-2776 Fax: (808)935-5934 March 22, 2004 Comm. No. &Ltqq Ref. To: W� Ref. DOti FT M Tn CT G l7 �_ � L C 3 Comm. No. &Ltqq Ref. To: W� Ref. DOti FT M TABLE OF CONTENTS Executive Summary Pape No. Report: A. Project Background 1 B. Environment 2 C. Discussion of Four Way Stop Control 2 D. Evaluation Methodology g D.1 Criteria for Four Way Stops g D.2 Evaluation of Speed Changes Attributable to the Four Way Stop g D.3 Discussion with Kona Traffic Safety Committee 11 E. Results of Evaluation 12 E.1 Criteria for Four Way Stops 12 E.2 Evaluation of Speed Changes Attributable to the Four Way Stop 13 E.3 Discussion with Kona Traffic Safety Council 14 F. Recommendations 15 Figures: Figure 1 Location of Study Intersection K TABLE OF CONTENTS Tables: Page No. Table 1 Warrnat 1 for Traffic Signals 16 Table 2 Warrant 2 for Traffic Signals 17 Table 3 Criterion C Warrant for Minimum Traffic Volumes 18 Table 4 Warrant for Left Turn Conflicts 19 Table 5 Statistical Analysis to Determine Whether or Not a Change in Travel Speed Occurred as a Result of Implementing a Four Way Stop at Kakalina Street 20 Appendices: Appendix A Traffic Turning Movement Counts Appendix B Speed Study Data Appendix C Responses of the Kailua Traffic Safety Committee EXECUTIVE SUMMARY EXECUTIVE SUMMARY EVALUATION OF A FOUR WAY STOP AT THE NANI KAILUA DRIVE/KAKALINA STREET INTERSECTION M&E Pacific, Inc., was retained to evaluate the effectiveness of a four way stop control at the intersection of Nani Kailua Drive and Kakalina Street, and recommend whether or not the four way stop should remain. Project Background. A four way stop was installed at the intersection of Nani Kailua Drive and Kakalina Drive on July 24, 2003, in compliance with County of Hawaii Ordinance Number 03 37. The ordinance also required a licensed engineer to evaluate and make a report to determine if the improvement should remain. The evaluation included consultation with the Kona Traffic Safety Committee and the Hawaii County Department of Public Works. Environment. Nani Kailua Drive is a two lane collector road running mauka- makai through the Kailua View Estates and Kona Heights subdivision. It is on an 8% slope in the vicinity of Kakalina Street and has wide pavements with only striping delineating the roadway from the shoulder. Discussion of Four Way Stops. Four way stops are generally implemented at intersections where traffic volumes have increased to the level where the minor street experiences excessive delay and are generally used as an interim measure until traffic signals can be installed. The Manual of Uniform Traffic Control Devices (MUTCD) has several guidelines and warrants for the implementation of four way stops. The four way stop was implemented at the subject intersection as a traffic calming device to control speeding in a residential neighborhood. Four way stops are not generally used as a traffic calming device for three major reasons: o Four way stops can increase delay on the major street to unacceptable levels; o Four way stops can increase the accident potential; and o Four way stops can cause drivers to speed on other portions of the road to make up for lost time. Evaluation Methodologv. Three different sets of criteria were evaluated to determine the effectiveness of the four way stop: the evaluation criteria set forth in the MUTCD, its effectiveness as a traffic calming device, and public opinion as expressed by the Kona Traffic Safety Committee. The results of the evaluation are discussed in the next section. The MUTCD lists four primary criteria based on traffic volumes and accident experience to determine whether or not a four way stop is warranted. It also lists four optional criteria based on engineering judgment. A ten hour manual traffic count was taken at the intersection on September 9, 2003, to provide traffic volume data to measure against the warrants. The County provided traffic accident data to measure against the traffic accident experience warrant. A field inspection determined that only one of the four optional warrants pertaining to controlling left turn conflicts could be evaluated. "Before and after" spot speed studies were conducted to determine if any changes in traffic speed on Nani Kailua Drive occurred as a result of the four way stop. The counts were taken on June 26, 2003, about a month before installation, and on August 28, 2003, about a month after installation. The members of the Kona traffic Safety Committee were contacted by email for their opinions at the start and near the completion of the study. Results of the Evaluation. The results for the three sets of criteria are discussed in the following paragraphs. With respect to the warrants listed in the MUTCD, none of the two primary traffic volume -related and traffic accident -related warrants are met. There are not enough vehicles at the intersection to warrant either traffic signals or a four way stop. There are also not sufficient numbers of vehicles to cause left turn conflicts; therefore, the one optional criterion is not met. With respect to speed changes effected by the four way stop, the following table summarizes the "before and after" results: Number of samples Average speed (mph) Minimum speed (mph) Maximum speed (mph) <20 mph 20-30 mph 31-35 mph >35 mph DOWNHILL RESULTS BEFORE AFTER 229 185 32.6 28.8 9 16 55 57 4(2%) 5(3%) 89(39%) 116(63%) 72(31%) 44(24%) 64(28%) 20(11%) UPHILL RESULTS BEFORE AFTER 256 222 30.8 26.0 17 13 44 52 4 (2%) 12(5%) 125(49%) 184(83%) 80(31%) 20(9%) 47(18%) 6(3%) There were 3.8 mile per hour (mph) and 4.8 mph decreases in average speed on the downhill and uphill directions of travel, respectively. Both of these differences are statistically significant at the 90% confidence level. The proportion of vehicles in the "20-30 mph" category also increased significantly, while the percentage in the "greater than 35" mph category decreased significantly, also. These changes indicate that the four way stop has had a dramatic impact on curbing speeding and has been very effective as a traffic calming device. However, the maximum observed speed did not decrease significantly. The maximum speed in the downhill direction was 55 mph or higher both before and after the four way stop installation. The maximum speed in the uphill direction increased from 47 mph to 52 mph. Two problems were noted. The data indicates that a diversion of traffic has occurred. County Department of Public Works staff said that they are receiving complaints from residents living on Aloha Kona Drive that there are more speeding cars on their street. During the 10 hour traffic count, the traffic counters reported 23 vehicles on Nani Kailua Drive running the stop sign, most at "full speed." This represents a hazardous traffic condition and is one reason multi -way stops are not used as traffic calming measures. With respect to the opinions of the Kona Traffic Safety Committee, five opinions were received to an initial email for comments. There were four opinions in favor of the four way stop and one not in favor. The dissenting opinion cited the unsightliness of the numerous sign posts and their opinion that drivers were speeding on other portions of the roadway to make up for lost time. The emails received in response to a draft summary report recognized the need for traffic calming measures but one person questioned the appropriateness of the four way stop as a traffic calming device. Recommendations. The above analysis shows that the four way stop at the Nani Kailua Drive/Kakalina Street intersection is not warranted by the criteria listed in the MUTCD. The current traffic volumes are too low to warrant either traffic signals or a four way stop. There have been no traffic accidents at this intersection so that the accident -related criterion is also not applicable. Therefore, the additional stop signs for Nani Kailua Drive should be removed by the applicant and the intersection restored to its original condition after the report has been discussed by the County Council. Leaving an unwarranted four way stop in place could create severe liability problems for the County and the engineering consultants involved in its design and evaluation. However, the study also verifies a serious speeding problem on Nani Kailua Drive and the need for mitigating action. A four way stop is not appropriate as a traffic calming device for either level or steep roadways. The choices for appropriate traffic control applications on this steep roadway with wide pavements and no raised shoulders are limited. For this environment, a demonstration program could be attempted to narrow the lane widths on Nani Kailua Drive for a limited length at one or more intersections. This could effected through restriping and reinforced with plastic delineator tubes. The specific details would need to be developed by an engineering design study. The results will most likely not be "aesthetically pleasing". In addition to or in lieu of physical measures, the residential associations may attempt an education program to enlighten residents of the speeding problem. Due to the layout of the roadway and neighborhood, almost all of the drivers on Nani Kailua Drive and its two parallel roadways, Aloha Kona Drive and Hoene Street, can be expected to be residents of the area. There should be very few "outside" drivers. The education campaign would focus on being "good neighbors." EVALUATION OF A FOUR WAY STOP AT THE NANI KAILUA DRIVE/KAKALINA STREET INTERSECTION EVALUATION OF A FOUR WAY STOP AT THE NANI KAILUA DRIVE/KAKALINA STREET INTERSECTION A four way stop control was installed during July 2003, at the Nani Kailua Drive/Kakalina Street intersection in Kailua-Kona, Hawaii. To comply with a County ordinance, M&E Pacific, Inc., was retained to evaluate the effectiveness of the four way stop control. This paper provides the background of the study, a discussion of the four way stop, a description of the evaluation methodology, the results of the evaluation, and recommendations for the future status of the four way stop. A. PROJECT BACKGROUND The Council of the County of Hawaii passed Ordinance Number 03 37 on March 13, 2003, for the approval of a subdivision rezoning. The Ordinance included the following clause: "The applicant shall provide a four-way stop condition at the Nani Kailua Drive/Kakalina Street intersection under the guidance of a licensed engineer within 90 days from the effective date of this ordinance. The impact of this improvement shall be evaluated by a licensed engineer in consultation with the Kona Traffic Safety Committee and the Department of Public Works for a six-month period. At that time the licensed engineer will report to the Council to determine if the improvement will remain. Should the study find that the 4 -way stop is not warranted, the applicant shall restore the intersection to its original condition" The applicant, Nani Kona Aina, LLC, retained a Kailua-Kona civil engineer to design the required improvement for County approval. The applicant also retained M&E Pacific, Inc., to evaluate the impact of this improvement and make a recommendation for its future status. The applicant installed the four way stop improvement at the Nani Kailua Drive/Kakalina Street intersection on July 24, 2003. B. ENVIRONMENT Nani Kailua Drive is a two lane collector road running mauka-makai through the Kailua View Estates and Kona Heights subdivision. It meets Queen Kaahumanu Highway Extension as a signalized intersection and continues makai to its terminus at Hualalai Road. On the roadway section mauka of Queen Kaahumanu Highway Extension, there are several intersecting local streets (including Kakalina Street) and many residential driveways along the length of the roadway. The pavement width is wide enough to accommodate paved shoulders on both sides. There are no raised curbs but only a painted stripe separating the roadway from the shoulder. The posted speed limit is 25 miles per hour. Vehicles could travel nonstop from Queen Kaahumanu Highway Extension to the mauka end of Nani Kailua Drive before the four way stop was implemented at Kakalina Street. The slope of the roadway is 8% in the vicinity of the Kakalina Street intersection. The types of traffic calming applications that are appropriate for this steep slope are generally limited to roadway narrowing and possibly chicanes (putting horizontal curves on the roadway). Kakalina Street is two lane local street generally running north -south. It allows access to two roadways that parallel Nani Kailua Drive: Aloha Kona Drive and Hoene Street. The location of the study intersection at Nani Kailua Drive and Kakalina Street is shown on Figure 1. C. DISCUSSION OF FOUR WAY STOP CONTROL Four way (or multiway if there are not four incoming approaches) stop control is an unsignalized intersection where all incoming approaches have a stop sign. Thus, all traffic entering the intersection are required to stop. This type of traffic control is generally used where traffic volumes on the major street (not stop controlled approaches) and minor street (stop sign controlled approaches) have increased to the level where the minor street traffic experiences excessive delay. Multiway stop control can help reduce the delays on the side streets 9 G Ta Kealakefie Qa�an ..........yG d � � qd �j�a a 19 Pawai PI fro i - � I odd o Study Intersection i n Ol I Ala 0naon d7G nab )m�y° R Y cc C -"fr.nim"'t°•a�" ��..e ^.. O .TY Y 00 � m cc m L,J J z Kawen Kakalina rx r Aloha Kona qr Ponce — m . ona i) m I � 1 TiG �»ce m� m ani ail a Dr Kam ainaHale n 3 =�YI� z. — �sFr fid. Z Qitx« .ts g f�iA .SA kryj _ L �m L 01. H Pit a aY �¢ .r R ulal•" '�Y` +ice ' Iv i+S'^'1n'Y"'SF vw'+GMF 1 jca 7� �, a ar a'+�ary•+^ ixA d � Y _ Huaiala a+ �14 MP q �z . �d FIGURE 1 LOCATION OF STUDY INTERSECTION 3. and is generally used as an interim measure until traffic signals can be installed. The Manual on Uniform Traffic Control Devices (MUTCD Millennium Edition 2001) has several cautions on applying the multi -way stop control: "Multiway stop control can be useful as a safety measure at intersections if certain traffic conditions exist. Safety concerns associated with multiway stops include pedestrians, bicyclists, and all road users expecting the other road users to stop. Multiway stop control is used where the volume of traffic on the intersecting roads in approximately equal". "The decision to install multiway stop conrol should be based on an engineering study." The MUTCD has several criteria that should be considered in the engineering study. These criteria can be considered as "soft" warrants for determining the needs for a multiway stop control condition. "A. Where traffic control signals are justified, the multiway stop is an interim measure that can be installed quickly to control traffic while arrangements are being made for the installation of the traffic control signal". B. A crash problem, as indicated by 5 or more reported crashes in a 12 month period that are susceptible to correction by a multiway stop installation. Such crashes include right- and left -turn collisions as well as right-angle collisions". "C. Minimum Volumes 1. The vehicular volume entering the intersection from the major street approaches (total for both approaches) averages at least 300 vehicles per hour for any 8 hours of an average day, and 2. The combined vehicular, pedestrian, and bicycle volume entering the intersection from the minor street approaches (total for both approaches) averages at least 200 units per hour for the same 8 hours, with an average delay of at least 30 seconds per vehicle during the highest hour." ram "D. Where no single criterion is satisfied, but where Criteria B, C.1, and C.2 are all satisfied to 80 percent of the minimum values." The MUTCD lists other optional criteria that can be considered in the engineering study. "A. The need to control left turn conflicts". "B. The need to control vehicle/ pedestrian conflicts near locations that generate high pedestrian volumes". "C. Locations where a road user, after stopping, cannot see conflicting traffic and is not able to safely negotiate the intersection unless conflicting cross traffic is also required to stop". "D. An intersection of two residential neighborhood collector (through) street of similar design and operating characteristics where multiway stop control would improve traffic operational characteristics of the intersection". In all, there are four primary and four optional criteria that can be used to determine whether or not four way stop control is warranted. Traffic calming devices have become popular across the nation as a means of controlling speeding and excess through traffic in residential neighborhoods. Although multiway stop control was previously used as a traffic calming device, current engineering practice does not favor using multiway stop control as a traffic calming device to reduce the speed of traffic on residential streets for three major reasons: o Multiway stops can increase delay on the major street to unacceptable levels; o Multiway stops can increase the potential for rear end accidents and accidents involving vehicles that run the stop signs; and o Multiway stops can cause people to speed on other portions of the road to make up for lost time. Also, installing unwarranted all way stops could condition drivers to run stop signs at other locations. The intent of the ordinance implementing the four way stop was to make it serve as a traffic calming device. 5. D. EVALUATION METHODOLOGY The evaluation of the four way stop at the Nani Kailua Drive/Kakalina Street intersection was done in three parts. The first part evaluated the eight criteria set forth in the MUTCD to determine whether or not the four way stop control is warranted. The second part evaluated the effectiveness of the four way stop control as a traffic calming device in reducing traffic speeds on Nani Kailua Drive. The third part describes discussion of the impacts of the four way stop control with members of the Kona Traffic Safety Committee. This section describes the methodology used for each evaluation process. D.1 Criteria for Four Way Stops The evaluation procedures used to evaluate the four primary and four optional criteria listed in the MUTCD to determine whether or not the four way stop control is warranted are discussed. Criterion A. Traffic Control Signals Justified. This first criterion is a warrant for traffic control signals. If a traffic control signal is justified at this location, then a four way stop is also warranted. The MUTCD lists eight warrants for determining the need for traffic control signals. The first two warrants pertain to traffic volumes and were considered applicable to this study. Warrant 1, the eight hour vehicular volume warrant, has two parts. Condition A, the minimum vehicular volume warrant, is "intended for application where a large volume of intersecting traffic is the principal reason to consider installing a traffic control signal." Traffic control signals could be considered if hourly vehicular volumes exceed the following standards for each of any eight hours of an average day: o Major street- 500 vph total on both approaches, o Minor street- 150 vph on only the high volume approach for the same eight hours. 1.1 Condition B, the interruption of continuous traffic warrant, is "intended for application where the traffic volume on a major street is so heavy that traffic on a minor street suffers excessive delay or conflict in entering of crossing the major street." Traffic control signals could be considered if hourly vehicular volumes exceed the following standards for each of any eight hours of an average day: o Major street- 750 vph total on both approaches, o Minor street- 75 vph on only the high volume approach for the same eight hours. Warrant 2, the four hour vehicular warrant, is "intended to be applied where the volume of intersecting traffic is the principal reason to consider installing a traffic control signal." The standard includes a graph with major street hourly volumes (total of both approaches) on the horizontal axis and the minor street hourly volumes( one direction only) on the vertical axis. The minor street volume must fall above the curve for the corresponding major street volume for any four hours on an average day. A ten hour traffic turning movment count was taken at the Nani Kailua Drive/Kakalina Street intersection on September 9, 2003, from 7:00 A.M. to 5:00 P.M., to obtain hourly traffic volumes on the major and minor streets. These traffic counts require traffic surveyors to position themselves at the intersection and record through and turning movements by 15 minute intervals. The traffic count worksheets are included in the Appendix. The hourly volumes were compared against the Warrants 1 and 2 volumes to determine whether or not the current traffic volumes exceeded the warrant volumes for more than eight hours a day. If any or both of the warrants were met, then the study intersection would be warranted for traffic control signalization, and the four way stop control would be warranted as a stop gap measure. The results of this analysis are reported in the next section. 7. Criterion B, Accident Experience The County was requested to provide two years of traffic accident data for the study intersection prior to the installation of the four way stop. The request also included whatever data would be available six months after the four way stop was installed to determine whether any changes in traffic accident patterns took place. The data was to be reviewed for the number of accidents per year and the types of accidents and compared to the five accidents per year and type of accident criteria. Criterion C, Minimum Volumes. The ten hour traffic turning movement count volumes were compared to the minimum volume warrant for multiway stops to determine whether or not the current traffic volumes on the major and minor streets exceeded the warrant volumes for more that eight hours a day. The major street minimum volume is 300 vph while the minor street minimum volume is 200 vph. The delay component of the warrant was not analyzed since delay data was not collected. Criterion D, Combination of Criteria. If the above criteria were not met, the criteria were reevaluated with 80% of the values for criteria B and C. The four way stop control would be warranted if both adjusted criteria were met. The evaluation results for the four criteria are reported in the next section. The optional criteria for multiway stops listed in the MUTCD were also evaluated for applicability to this study. If the optional criterion was applicable, then the evaluation methodology is described. Optional Criterion A, Controlling Left Turn Conflicts The ten hour traffic turning movement count volumes show the volume of through and turning movements, including left turns made from Kakalina Street. A level of service analysis was made to determine if a left turn problem exists. A level of service F for the left turn movement would indicate the need for mitigating actions. Since both approaches of Kakalina Street are only one lane, all movements F1 must be made from the same lane. Consequently, the level of service was calculated for the approach as a whole. Optional Criterion B, Controlling Vehicle/Pedestrian Conflicts Although pedestrian volumes were not counted, high volumes of pedestrians were not observed. There are no locations that generate large volumes of pedestrian traffic in this area. Therefore, this criterion is not applicable to this study. Optional Criterion C, Blind Intersections. A field review of the study intersection showed that there were no sight distance problems for the drivers on Kakalina Street. Therefore, this criterion is not applicable to this study. Optional Criterion D, Intersection of Two Residential Collector Streets Nani Kailua Drive functions as a collector street while Kakalina Street is a local street. Therefore, this criterion is not applicable to this study. This criterion may be applicable in the distant future as the area develops and Kakalina Street becomes a collector roadway. In all, three of the four optional criteria were not applicable to this study. Therefore, only optional criterion A was evaluated and the results are reported in the next section. D.2 Evaluation of Speed Changes Attributable to the Four Way Stop A "before and after" spot speed study was conducted to determine if any changes in traffic speed on Nani Kailua Drive occurred as a result of the four way stop control. Spot speed counts were taken on June 26, 2003, about a month before the multi -way stop signs were installed, and on August 28, 2003, about a month after the signs were installed. A month is generally sufficient time for traffic to get adjusted to new traffic control devices. The spot speed study was conducted per the methodology described in the Institute of Transportation Engineers Transportation and Traffic Engineering Handbook (2nd Edition, 1982). Two lines 88 feet apart were marked on both a downhill and uphill lanes of Nani Kailua Drive about 150 feet mauka of the subject intersection. This distance is sufficiently far from the new stop sign to avoid the effects of braking for the stop control sign. Traffic surveyors positioned themselves on the road shoulder so that they could see oncoming vehicles cross both lines. Two traffic surveyors were used, one for each direction of travel. With stop watches, the traffic surveyors noted the time (in hundredths of seconds) for a vehicle to travel between the two lines and wrote the time on a paper form, one sheet for every 30 minute interval. The traffic surveyors were instructed to record as many vehicles as best they could, but they did not have to record each vehicle since spot speed studies do not require that each vehicle be surveyed. Also, they were to record only the first car in a queue of vehicles, since the following vehicles' speeds would be affected by the first vehicle. The surveyors reported that they counted almost every vehicle that passed by. The spot speed surveys were taken from 9:30 A.M. to 12 noon, and from 1:00 to 3:30 PM, for both survey days. Spot speed surveys are generally taken in off peak periods when traffic is generally not affected by traffic congestion. Traffic flow during peak traffic periods are generally affected by congestion and are normally not surveyed. The collected travel times were then input into Excel spreadsheets by direction of travel and by 30 minute intervals. The travel times within each interval were then sorted into descending order (slowest to fastest). For each travel time sample, the formula 6000/ (hundredths of seconds) was used to convert the travel time into speed (miles per hour, mph). The following statistics were generated for each half hour interval and the entire day's sample: o number of samples, o average speed, o standard deviation, o minimum speed, and o maximum speed. 10. Also, the number of samples were categorized into four categories: o less than 20 mph (greater than 5 mph below the speed limit), 0 20 to 30 mph (within 5 mph of the speed limit), 0 31-35 mph (5-10 mph over the speed limit), and 0 over 35 mph (greater than 10 mph over the speed limit). The worksheets for the spot speed study before and after the sign installation, and uphill and downhill direction of travel, are included in the Appendix. A statistical analysis was conducted to determine whether any observed speed changes were statistically valid. A t-test was conducted between the "before" and "after" average speeds for each direction of travel. For this test, the null hypothesis tested was that there is no difference in the mean sample speeds at a 90% confidence level. The alternative hypothesis was that there is a difference. The null hypothesis was accepted if the calculated t -statistic was less than the t -statistic for the sample size and assumed confidence level. Otherwise, the alternative hpothesis was accepted. The formula for the t -statistic is: t = (Xa — Xb) — (Ua — Ubl Square Root {SP2 ((1/Na)-(1/Nb)]} where, t = calculated t -statistic, SP2 = _ (Na-1)Sa2 + (Nb-1)Sb2 the pooled variance, Na + Nb -2 Xa,Xb = mean sample after and before speeds, Ua,Ub = mean population after and before speeds, Na,Nb = Number of after and before samples, Sae, Sb2 = Variance of before and after means. D.3 Discussion with Kona Traffic Safety Committee Members of the Kona Traffic Safety Committee were contacted twice by email to obtain their opinions of the four way stop. The first contact was made in early September 2003 about a month after the implementation date to obtain initial opinions. A report summarizing the findings to date (but with no conclusions) 11. was sent out in January 2004 about five months after to determine if there had been any changes in opinions. The email messages and summary report are included in the Appendix E. RESULTS OF EVALUATION E.1 Criteria for Four Way Stops The five applicable criteria were evaluated to determine if a four way stop is warranted. Criterion A, Traffic Control Signals Justified. The hourly traffic count volumes are compared with the traffic control signal warrants 1 and 2 on Tables 1 and 2, respectively. The hourly volumes do not exceed the warrant volumes for any hour of the day; thus, traffic control signal warrants are not met. Discussions with the County Department of Public Works staff indicated that they thought that traffic control signals are not warranted at this intersection. Therefore, this criterion for traffic signals is not met and a four way stop is not warranted. Criterion B, Accident Experience. The County Police Department reported that there were no traffic accidents for the two year period. Therefore, this criterion for accident experience is not met and a four way stop is not warranted Criterion C, Minimum Volumes. Table 3 lists the hourly volumes counted on each approach during the ten hour count. It also notes whether or not the major and minor street volumes exceed the minimum volumes criteria for multiway stops. The table shows that the major street (Nani Kailua Drive) and the minor street (Kakalina Street) volumes did not exceed the minimum volumes for any hour of the day. Therefore, this criterion for minimum volumes is not met and a four way stop is not warranted. Criterion D, Combination of Criteria. Since the above criteria were not met, the criteria were reevaluated with 80% of the values for criteria B and C. Since there were no reported traffic accidents and the adjusted traffic volume criteria 12. are not exceeded, this combination of criteria is not met and a four way stop is not warranted. Optional Criterion A, Controlling Left Turn Conflicts The results of this evaluation are shown on Table 4. The levels of service for the outbound movements from both approaches of Kakalina Street and the left turns movements from Nani Kailua Drive are at level A for each hour of the 10 hour period. This would indicate that a left turn conflict problem did not exist at this intersection. Therefore, this criterion is not met and a four way stop is not warranted. In summary, none of the criteria/warrants for implementing multi -way stops were met. E.2 Evaluation of Speed Changes Attributable to the Four Way Stop The results of the "before" and "after" speed surveys are shown on Table 5. The results are summarized below: Number of samples Average speed (mph) Minimum speed (mph) Maximum speed (mph) <20 mph 20-30 mph 31-35 mph >35 mph DOWNHILL RESULTS BEFORE AFTER 229 185 32.6 28.8 9 16 55 57 4(2%) 5(3%) 89 (39%) 116(63%) 72(31%) 44(24%) 64(28%) 20(11%) UPHILL RESULTS BEFORE AFTER 256 222 30.8 26.0 17 13 44 52 4(2%) 12(5%) 125(49%) 184(83%) 80(31%) 20(9%) 47(18%) 6(3%) There were 3.8 mph and 4.8 mph decreases in average speed on the downhill and uphill directions of travel, respectively. Both of these differences are statistically significant at the 90% confidence level. The proportion of vehicles in the "20-30 mph" category also increased significantly, while the percentage in the "greater than 35" mph category decreased significantly, also. These changes indicate that the four way stop has had a dramatic impact on curbing speeding and has been very effective as a traffic calming device. 13. However, the maximum observed speed did not decrease significantly. The maximum speed in the downhill direction was 55 mph or higher both before and after the four way stop installation. The maximum speed in the uphill direction increased from 47 mph to 52 mph. Two problems were noted. A problem that arises when traffic calming devices are not installed as part of an areawide program is speeding drivers who migrate to alternate routes. The speed survey data shows that the number of samples in each direction of travel decreased significantly after the sign installation. The downhill sample decreased from 229 to 185, a 19 percent decrease. The uphill sample decreased from 256 to 222, a 13 percent decrease. While spot speed studies are not designed to count every vehicle, the surveyors reported counting almost all vehicles so that these counts are indicative of traffic volumes during the five hours counting periods. The observed volume differences are larger than would occur in daily and seasonal variations of traffic volumes, although both counts were made in the summer months. Therefore, the data indicates that a diversion of traffic has occurred. County Department of Public Works staff said that they are receiving complaints from residents living on Aloha Kona Drive, a mauka-makai roadway that parallels Nani Kailua Drive, that there are more speeding cars on their street. Speeding cars on Nani Kailua Drive running the stop sign was another problem noted. During the 10 hour traffic count, the traffic counters reported 23 vehicles running the stop sign, most at "full speed." This represents a hazardous traffic condition and is one reason multi -way stops are not used as traffic calming measures. E.3 Discussion with Kona Traffic Safety Council Six letters/notes were initially received from residents in response to an email request from the Kona Traffic Safety Committee for comments on the four way stop. Five responses were in favor while one was not. The Kailua View Estates 14. Homeowners Association, Kona Heights Property Owner's Association and three residents wrote in favor of the four way stop. These responses generally acknowledged the speeding problem, the beneficial effect that the four way stop has had, and asked that more four way stops be implemented. One resident thought that the four way stop was not an effective traffic control device and was also unsightly. Copies of the letters and email notes (edited to remove personal information) are included in the Appendix. A summary report of the study findings without any recommendations was sent to the committee via email in January. Several more email messages were subsequently received but several are not included in the Appendix because of their personal exchanges. In general, the need for traffic calming devices is recognized but one person questioned the appropriateness of the four way stop as a traffic calming device. F. RECOMMENDATIONS The above analysis shows that the four way stop at the Nani Kailua Drive/Kakalina Street intersection is not warranted by the criteria listed in the MUTCD. The current traffic volumes are too low to warrant either traffic signals or a four way stop. There have been no traffic accidents at this intersection so that the accident -related criterion is also not applicable. Therefore, the additional stop signs for Nani Kailua Drive should be removed by the applicant and the intersection restored to its original condition after the report has been discussed by the County Council. Leaving an unwarranted four way stop in place could create severe liability problems for the County and the engineering consultants involved in its design and evaluation. However, the study also verifies a serious speeding problem on Nani Kailua Drive and the need for mitigating action. A four way stop is not appropriate as a traffic calming device for either level or steep roadways. Installing an unwarranted four way stop could condition drivers to run stop signs and 15. reduce the effectiveness of stop signs at other locations. The choices for appropriate traffic control applications on this steep roadway with wide pavements and no raised shoulders are limited. For this environment, a demonstration program could be attempted to narrow the lane widths on Nani Kailua Drive for a limited length at one or more intersections. This could effected through restriping and reinforced with plastic delineator tubes. Openings should be left at driveways and to allow vehicles to enter parking areas on the shoulders. Planters should not be used as delineators since they could become accident hazards. The specific details would need to be developed by an engineering design study. The results will most likely not be "aesthetically pleasing". In addition to or in lieu of physical measures, the residential associations may attempt an education program to enlighten residents of the speeding problem. Due to the layout of the roadway and neighborhood, almost all of the drivers on Nani Kailua Drive and its two parallel roadways, Aloha Kona Drive and Hoene Street, can be expected to be residents of the area. There should be very few "outside" drivers. The education campaign would focus on being "good neighbors." 16. TABLES TIME Nani Kailua Drive TABLE. 1 West- East- Two PERIOD bound bound Way 17:00-8:00 AM 73 45 .8:00-9:00 AM 68 70 9:00-10:00 AM 51 . 61 10:00-11:00 AM 33 48 11:00-12:00 AM 49 73 112:00-1:00 PM 56 68 11:00-2:00 PM 40 68 2:00-3:00 PM 52 93 ;3:00-4:00 PM 53 108 14:00-5:00 PM 44 120 • U N TABLE. 1 WARRANT- 1 FOR TRAFFIC SIGNALS WARRANT 1 - 8 Hour Vehicular Warrant Condition A, Minimum Condition B, Interuption of Vehicular Volume Warrant Contimuous Traffic Warrant Is 2 way Is highest Is 2 way Is highest Kakalina Street major street minor street major street minor street South- North- volume >500 volume >150 volume>500 volume >75 bound bound vph? vph? vph? vph? 118 13 23 NO NO NO NO 138 16 10 NO NO NO NO 112 16 15 NO NO NO NO 81 9 10 NO NO NO NO 122 11 15 NO NO NO NO 124 17 14 NO NO NO NO 108 9 9 NO NO NO NO 145 19 11 NO NO NO NO 161 9 15 NO NO NO NO 164 20 '12 NO NO NO NO Do volumes exceed Do volumes exceed standards for 8 hours of the standards for 8 hours of the day? NO day? NO • U N TIME PERIOD 7:00-8:00 AM 8:00-9:00 AM 9:00-10:00 AM 10:00-11:00 AM 11:00-12:00 AM 12:00-1:00 PM 1:00-2:00 PM 2:00-3:00 PM 3:00-4:00 PM 4:00-5:00 PM 17. TABLE 2 WARRANT 2 FOR TRAFFIC SIGNALS Warrant 2 4 Hour Vehicular Warrant Standard- Is Highest Nani Kailua Drive Kakalina Street required Minor Street West- East- Two South- North- Minor Street Volume>Stan bound bound Way bound bound volume dard vph 73 45 118 13 23 320 NO 68 70 138 16 10 320 NO 51 61 112 16 15 320 NO 33 48 81 9 10 320 NO 49 73 122 11 15 320 NO 56 68 124 17 14 320 NO 40 68 108 9 9 320 NO 52 93 145 19 11 320 NO 53 108 161 9 15 320 NO 44 120 164 20 12 320 NO Do volumes exceed standards for 4 hours of the day? NO 17. TABLE 3 CRITERION C WARRANT FOR MINIMUM TRAFFIC VOLUMES 18. Criterion C Warrant Minimum traffic volumes Is 2 way Is 2 way TIME Nani Kailua Drive Kakalina Street major street minor street West- East- Two South- North- Two volume >300 volume >200 PERIOD bound bound Way bound bound Way vph? vph? 7:00-8:00 73 45 118 13 23 36 NO NO 8:00-9:00 68 70 138 16 10 26 NO NO 9:00-10:00 51 61 112 16 15 31 NO NO 10:0011:00 33 48 81 9 10 19 NO NO 11:00-12:00 49 73 122 11 15 26 NO NO 12:00-1:00 56 68 124 17 14 31 NO NO 1:00-2:00 40 68 108 9 9 18 NO NO 2:00-3:00 52 93 145 19 11 30 NO NO 3:00-4:00 53 108 161 9 15 24 NO NO 4:00-5:00 44 120 164 20 12 32 NO NO Do volumes exceed standards for 8 hours of the day? NO 18. 19. TABLE 4 WARRANT FOR LEFT TURN CONFLICTS LEVEL OF SERVICE BY APPROACH Kakalina Drive Nani Kailua Drive TIME East West North South Bound Bound PERIOD Bound Bound Left Left 7:00-8:00 AM A A A A 8:00-9:00 AM A A A A 9:00-10:00 AM A A A A 10:00-11:00 AM A A A A 11:00-12:00 AM A A A A 12:00-1:00 PM A A A A 1:00-2:00 PM A A A A 2:00-3:00 PM A A A A 3:00-4:00 PM A A A A 4:00-5:00 PM A A A A 19. TABLE 5 STATISTICAL ANALYSIS TO DETERMINE WHETHER OR NOT A CHANGE IN TRAVEL SPEED OCCURRED AS A RESULT OF IMPLEMENTING A FOUR WAY STOP AT KAKALINA STREET Null Hypothesis: mean speeds before and after impementation are equal Alternate Hypothesis: mean speeds before and after implentation are not equal Confidence interval: 90% Therefore, t (inf,0.05) = 1.645 Accept null hypthesis if t(calc) is less than t(inf,0.05) VARIABLE Before mean speed After mean speed Before sample size After sample size Before standard dev Before variance After standard dev. After variance Difference of means [(1 /n)+(1 /n)] [(n-1)"var) before [(n-1)'var] after n+n-2 pooled variance denominator sqrt(denominator) t(calc) _ t(calc) > t(inf,0.05) ? Accept null hyp.? DOWNHILL DIRECTION OF TRAVEL 32.6 28.8 229 185 6.49 42.12 5.44 29.59 UPHILL DIRECTION OF TRAVEL 30.8 26.0 256 222 5.56 30.91 4.70 22.09 3.8 4.8 0.004367 + 0.005405 = 0.009772 0.003906 9603 + 7883 5445 = 15049 412 37 0.160 0.399 9.51 Yes No, change in speed occurred 20. + 0.004505 = 0.008411 4882 = 12765 476 27 0.105 0.324 14.83 Yes No, change in speed occurred APPENDICES U22A 8101 TRAFFIC TURNING MOVEMENT COUNTS TRAFFIC TURNING MOVEMENT COUNT Nani Kailua Drive Four Way Stop Evaluation Nani kailua Drive LOCATION: Nani Kailua Drive/Kakalina Street <------------ 1 2 3 ------------> DATE: - September 9, 2003, Tuesday To Waimea I I I To Keauhou TIME: 7:00a --5:00p <- v > WEATHER: Clean and sunny 7 ---" --- 10 RECORDER: Richard Alberts Kakalina 8 ---> <--- 11 Tom Lemanski (Movements 7-1 Street 9 ---v v--- 12 <- --> I I I 74 5 6 TIME MOVEMENT NUMBER PERIOD 1 2 3 4 5 6 7 8 9 10 11 12 TOT 7:00-7:15 8 1 6 3 1 3 22 7:15-7:30 25 4 1 4 7 41 7:30-7:45 22 1 11 1 1 2 7 45 7:45-8:00 18 3 11 3 5 1 5 46 7:00-8:00 0 73 0 5 32 8 1 0 12 0 1 22 154 8:00-8:15 1 18 4 10 2 1 3 2 41 8:15-8:30 16 2 15 4 4 4 45 8:30-8:45 12 1 4 12 1 6 2 38 8:45-9:00 20 4 11 1 2 2 40 8:00-9:00 1 66 1 14 48 8 0 1 15 0 0 10 164 9:00-9:15 17 1 14 1 4 1 38 9:15-9:30 2 5 3 10 1 1 4 4 30 9:30-9:45 15 1 5 5 2 3 1 4 36 9:45-10:00 10 1 5 11 4 3 1 4 39 9:00-10:00 2 47 2 14 40 7 1 1 14 0 2 13 143 10:00-10:15 10 3 12 1 1 7 34 10:15-10:30 10 1 15 3 1 4 1 35 10:30-10:45 13 1 10 3 2 1 1 31 10:45-11:00 0 10:0011:00 0 33 0 5 37 6 0 2 7 1 0 9 100 11:00-11:15 11 5 14 5 1 3 39 11:15-11:30 13 1 4 15 1 3 5 42 11:30-11:45 2 10 2 13 3 2 1 3 36 11:45-12:00 12 2 13 1 1 2 31 11:00-12:00 1 2 46 1 13 55 5 0 0 11 2 0 13 148 TRAFFIC TURNING MOVEMENT COUNT Nani Kailua Drive Four Way Stop Evaluation LOCATION: Nani Kailua Drive/Kakalina Street DATE: September 9, 2003, Tuesday TIME: 7:00a --5:00p WEATHER: Clean and Sunny RECORDER: Richard Alberts Tom Lemanski (Movements 7-1 Nani kailua Drive < 1 2 3 > To Waimea � I � To Keauhou <- v > 7 10 Kakalina 8 ---> <--- 11 Street 9 ---v v--- 12 7 4 5 6 TIME MOVEMENT NUMBER PERIOD 1 2 3 4 5 6 7 8 9 10 11 12 TOT/ 12:00-12:15 14 4 16 1 6 1 3 45 12:15-12:30 17 15 2 4 1 2 41 12:30-12:45 11 1 4 12 1 1 1 31 12:45-1:00 13 2 8 3 6 6 38 12:00-1:00 0 55 1 10 51 7 0 1 16 1 1 12 155 1:00-1:15 13 2 19 3 1 2 40 1:15-1:30 9 3 13 2 2 3 32 1:30-1:45 11 2 13 1 3 30 1:45-2:00 7 2 8 3 4 24 1:00-2:00 0 40 0 9 53 6 0 0 9 0 0 9 126 2:00-2:15 15 5 21 2 1 1 1 2 48 2:15-2:30 8 3 15 2 1 4 1 34 2:30-2:45 16 5 14 2 5 3 45 2:45-3:00 13 3 17 6 4 1 4 48 2:00-3:00 0 52 0 16 67 10 1 4 14 1 0 10 175 3:00-3:15 8 1 17 3 2 2 1 34 3:15-3:30 11 2 20 5 1 1 6 46 3:30-3:45 15 3 26 4 2 1 2 53 3:45-4:00 19 9 14 4 1 1 4 52 3:00-4:00 0 53 0 15 77 16 1 2 6 0 2 13 185 4:00-4:15 8 7 15 3 1 4 1 39 4:15-4:30 14 8 27 3 3 1 4 60 4:30-4:45 8 1 4 17 1 8 1 3 43 4:45-5:00 14 9 23 3 1 2 2 54 4:00-5:00 1 0 44 0 25 69 26 1 2 17 2 0 101 196 APPENDIX B SPEED STUDY DATA SPEED STUDY DATA TAKEN JUNE 26, 2003, BEFORE INSTALLATION OF FOUR WAY STOP NANI KAILUA DRIVE SPEED STUDY TAKEN JUNE 26, 2003, PRIOR TO INSTALLTION OF4 WAY STOP AVERAGE SPEED (Miles per hour) IN DOWNHILL DIRECTION HALF HOUR PERIOD BEGINNING AT: 9:30A 10:OOA 10:30A 11:OOA 11:30A 1:OOP 1:30P 2:00P 2:30P 3:OOP 23 9 16 24 26 22 21 23 20 16 23 22 18 27 26 23 23 23 24 25 23 27 22 30 29 24 24 24 27 27 27 27 23 30 31 24 26 24 28 28 27 28 27 30 32 27 27 26 28 28 27 29 28 31 32 27 28 27 30 28 29 30 28 31 32 28 30 28 30 29 30 30 29 31 32 29 30 29 30 29 30 30 29 32 32 31 30 29 30 29 31 30 30 34 32 32 32 29 30 29 31 32 30 34 33 32 34 29 31 30 31 34 31 34 33 33 36 30 32 30 31 34 32 35 34 34 37 30 32 31 32 34 34 36 34 34 45 30 33 32 33 34 36 37 35 43 30 34 33 34 34 36 40 35 46 30 34 34 34 35 37 41 35 47 32 34 34 35 36 43 41 37 55 33 34 35 38 36 50 42 37 33 34 35 42 37 43 37 35 35 36 42 38 47 40 35 35 37 44 40 42 38 38 38 45 41 43 38 38 38 41 48 40 38 38 45 41 38 38 41 40 38 42 40 39 42 43 42 49 HALF HOUR PERIOD BEGINNING AT: 9:30A 10:OOA 10:30A 11:OOA 11:30A 1:OOP 1:30P 2:OOP 2:30P 3:OOP 23 25 19 21 24 18 14 27 29 29 32 32 30 35 34 33 30 31 33 33 6.40 7.21 8.04 5.76 5.10 9.31 6.22 5.66 5.20 6.22 23 9 16 24 26 22 21 23 20 16 45 45 50 47 48 55 45 42 42 49 0 1 2 0 0 0 0 0 0 1 9 9 9 5 3 8 9 16 10 11 9 7 3 8 14 6 2 5 11 7 5 8 5 8 7 4 3 6 8 10 TOTAL 229 NUMBER OF SAMPLES 32.6 AVERAGE SPEED 6.49 STANDARD DEVIATION 9 MINIMUM SPEED 55 MAXIMUM SPEED TOTAL % SPEED CLASS 4 2% < 20 MPH 89 39% 20-30 MPH 72 31% 31-35 MPH 64 28% >35 MPH NANI KAILUA DRIVE SPEED STUDY 1 1 2 0 0 TAKEN JUNE 26, 2003, PRIOR TO INSTALLTION OF4 WAY STOP 0 AVERAGE SPEED (Miles per hour) IN UPHILL DIRECTION 2% < 20 MPH 16 11 5 6 HALF HOUR PERIOD BEGINNING AT: 10 17 19 9:30A 10:OOA 10:30A 11:OOA 11:30A 1:00P 1:30P 2:OOP 2:30P 3:OOP 12 21 17 18 17 22 23 21 22 22 21 7 22 23 25 18 26 24 24 22 23 22 23 24 26 28 26 25 27 22 23 23 23 25 26 28 26 25 27 23 24 24 24 26 28 28 29 25 27 24 24 24 25 27 30 30 29 25 28 26 24 25 25 27 32 30 29 26 28 27 24 26 26 29 32 30 30 27 28 28 25 27 26 29 33 31 30 27 29 28 25 28 28 29 34 31 31 28 30 28 25 28 28 30 34 32 31 28 31 29 26 28 28 30 35 34 32 29 31 29 27 29 29 31 35 36 32 29 32 29 27 29 29 31 36 41 32 29 32 29 28 30 30 32 37 42 32 29 33 30 29 30 30 32 39 47 33 30 38 30 29 31 32 32 45 36 30 38 30 29 31 33 32 39 31 38 31 29 32 33 33 40 32 38 32 30 32 33 34 45 33 41 32 31 33 34 34 46 33 47 32 32 33 35 34 34 47 32 32 33 36 35 36 32 32 34 38 36 39 33 32 34 38 36 41 34 32 35 38 37 41 34 32 35 43 37 34 33 36 38 35 33 37 44 35 34 39 36 35 41 36 35 41 38 38 45 40 40 HALF HOUR PERIOD BEGINNING AT: 9:30A 10:OOA 10:30A 11:00A 11:30A 1:OOP 1:30P 2:OOP 2:30P 3:00P TOTAL 27 29 17 16 21 26 22 34 32 32 256 NUMBER OF SAMPLES 30 31 32 32 32 30 32 31 29 31 30.8 AVERAGE SPEED 5.59 5.28 6.23 7.80 6.03 4.98 6.87 4.78 4.24 5.80 5.65 STANDARD DEVIATION 21 17 18 17 22 23 21 22 22 21 17 MINIMUM SPEED 43 44 45 47 46 41 47 40 38 45 47 MAXIMUM SPEED TOTAL % SPEED CLASS 0 1 1 2 0 0 0 0 0 0 4 2% < 20 MPH 16 11 5 6 9 17 10 17 19 15 125 49% 20-30 MPH 6 11 7 4 7 5 5 12 12 11 80 31% 31-35 MPH 5 6 4 4 5 4 7 5 1 6 47 18% >35 MPH SPEED STUDY DATA TAKEN AUGUST 28, 2003, AFTER INSTALLATION OF FOUR WAY STOP NANI KAILUA DRIVE SPEED STUDY 10:OOA 10:30A 11:OOA 11:30A 1:00P TAKEN AUGUST 28, 2003, AFTER INSTALLTION OF4 WAY STOP AVERAGE SPEED (Miles per hour) IN DOWNHILL DIRECTION 17 16 24 HALF HOUR PERIOD BEGINNING AT: 23 29 9:30A 10:OOA 10:30A 11:OOA 11:30A 1:OOP 1:30P 2:OOP 2:30P 3:OOP 22 23 22 19 22 18 20 16 19 21 24 23 24 23 23 18 23 21 20 22 26 24 24 23 25 22 25 23 23 22 27 24 25 25 26 22 26 26 23 23 27 26 28 25 26 24 26 26 24 24 27 26 29 26 26 24 28 26 24 25 28 26 29 26 27 25 29 26 24 25 28 30 30 26 28 26 29 29 25 25 28 30 31 26 29 26 29 29 25 26 29 32 32 27 31 28 30 30 25 26 30 33 32 28 32 28 31 30 26 26 30 35 32 28 32 30 31 30 27 26 31 42 33 30 33 31 31 31 28 27 37 33 31 33 32 32 31 28 27 38 35 34 34 32 34 31 28 28 57 36 41 32 32 30 28 36 32 32 30 29 33 32 31 29 34 34 32 30 38 35 33 33 39 35 36 36 39 36 36 41 37 38 45 38 42 HALF HOUR PERIOD BEGINNING AT 9:30A 10:OOA 10:30A 11:OOA 11:30A 1:00P 1:30P 2:OOP 2:30P 3:OOP 15 13 16 17 16 24 15 25 21 23 29 29 31 28 29 30 28 30 27 28 4.16 5.54 7.86 4.62 4.85 7.16 3.69 5.53 4.27 4.34 22 23 22 19 22 18 20 16 19 21 38 42 57 36 41 45 34 42 36 38 0 0 0 1 0 2 0 1 1 0 12 9 8 12 9 10 10 11 16 19 1 3 7 2 6 7 5 9 3 1 2 1 1 2 1 5 0 4 1 3 TOTAL 185 NUMBER OF SAMPLES 28.8 AVERAGE SPEED 5.44 STANDARD DEVIATION 16 MINIMUM SPEED 57 MAXIMUM SPEED TOTAL % SPEED CLASS 5 3% < 20 MPH 116 63% 20-30 MPH 44 24% 31-35 MPH 20 11% >35 MPH NANI KAILUA DRIVE SPEED STUDY 2 0 0 0 3 TAKEN AUGUST 28, 2003, AFTER INSTALLTION OF4 WAY STOP 9 12 AVERAGE SPEED (Miles per hour) IN UPHILL DIRECTION 13 26 14 33 26 26 HALF HOUR PERIOD BEGINNING AT: 1 0 1 1 9:30A 10:OOA 10:30A 11:OOA 11:30A 1:OOP 1:30P 2:OOP 2:30P 3:OOP 1 13 13 19 23 20 21 17 18 21 19 17 18 19 24 20 21 18 20 21 20 18 24 20 25 22 22 19 20 22 20 24 25 21 25 23 22 22 20 22 21 24 26 21 29 24 22 23 21 23 22 25 26 21 29 25 22 24 21 23 23 25 27 21 30 25 23 24 21 24 23 26 27 22 30 26 24 25 21 24 23 26 27 25 31 26 25 25 22 25 24 27 28 25 39 27 25 26 22 25 24 27 28 26 28 25 26 22 25 24 30 28 26 28 25 26 22 25 25 33 30 26 30 26 26 22 25 25 30 26 32 26 26 23 26 25 38 28 26 29 23 26 25 39 29 26 30 23 26 26 29 26 30 23 27 26 29 26 31 24 27 26 30 27 32 24 27 26 35 27 25 27 26 28 25 29 27 28 26 29 27 30 26 29 28 30 26 29 28 30 26 30 29 30 27 30 29 31 27 30 32 27 31 32 28 31 32 28 32 36 28 32 36 29 32 29 37 30 43 31 52 32 32 HALF HOUR PERIOD BEGINNING AT: 9:30A 10:OOA 10:30A 11:OOA 11:30A 1:OOP 1:30P 2:OOP 2:30P 3:00P TOTAL 13 16 20 10 14 32 19 37 26 35 222 NUMBER OF SAMPLES 24 27 25 29 25 27 25 25 26 27 26.0 AVERAGE SPEED 5.24 6.31 4.31 4.77 3.49 4.02 4.16 3.71 2.64 6.48 4.70 STANDARD DEVIATION 13 13 19 23 20 21 17 18 21 19 13 MINIMUM SPEED 33 39 35 39 32 36 32 32 30 52 52 MAXIMUM SPEED TOTAL % SPEED CLASS 3 2 2 0 0 0 3 1 0 1 12 5% < 20 MPH 9 12 17 8 13 26 14 33 26 26 184 83% 20-30 MPH 1 0 1 1 1 6 2 3 0 5 20 9% 31-35 MPH 0 2 0 1 0 0 0 0 0 3 6 3% >35 MPH APPENDIX C RESPONSES OF THE KAILUA TRAFFIC SAFETY COMMITTEE RESPONSES OF THE KAILUA TRAFFIC SAFETY COMMITTEE INITIAL COMMENTS RECEIVED IN SEPTEMBER 2003 INITIAL EMAIL MEMO SENT TO ANN PETERSON, CHAIR OF THE KONA TRAFFIC SAFETY COMMITTEE Sent: Saturday, September 06, 2003 10:17 AM Subject: Nani Kailua Drive/Kakalina Street 4 way stop To Members of the Kona Traffic Safety Council: I am Warren Yamamoto, a Traffic Engineer with M&E Pacific, Inc. Our firm was retained by Bolton, Inc, to evaluate the effectiveness of the four way stop installed at the Nani Kailua Drive/Kakalina Street intersection. This is in fulfillment of requirements of Ordinance 30 06. The four way stop was installed in late July 2003 and the evaluation period will continue for six months until January 2004. One of the requirements is to coordinate with your committee. Anne Peterson suggested I communicate with you via your email address to get dialogue started. I would like your comments on the project now and throughout the project to see if there are any changes in opinions. Anne said that your members who live in this area would be better able to give your opinions than she. I ask that you provide me with either individual responses or a "committee" response via my email on your initial reaction to the four way stop. If you have any questions, please send them to me and I will try to answer them. Thank you for your cooperation and understanding in this matter. Yours truly, Warren M. Yamamoto M&E Pacific, Inc. INITIAL EMAIL DISTRIBUTION FROM ANN PETERSON TO COMMITTEE MEMBERS Subject: Re: Nani Kailua Drive/Kakalina Street 4 way stop Date: Sun, 7 Sep 2003 07:59:01 Good morning KTSC members, Here's our opportunity to provide input on the four-way stops signs on = Nani Kailua ... (see message below) We can come up with a committee stance at the next KTSC meeting, but as = stated below, I think the most valuable input will come from the Kona = Heights and Kailua View Estates residents, please circulate. Aloha, Ann RESPONSES TO INITIAL REQUEST FOR COMMENTS ARE ON THE FOLLOW PAGES (Responses have been edited to remove personal identifying information) RESPONSEI Date: Mon, 17 Nov 2003 Subject: Traffic Sign on Nani Kailua Drive, Kailua-Kona I am writing to comment on the installation of the stop sign at the intersection of Nani Kailua Drive and Kakalina Street, Kailua-Kona. I reside at 75-xxx Nani Kailua Drive. I want to commend the installation of this stop sign!! It has been long overdue. The increase of traffic on Nani Kailua and especially the unmonitored and constant speeding of cars up and down the street, has been a source of frustration for most of the residents on this street. This is a residential neighborhood, yet you would think it was a highway, the way speeding drivers use the street. I would hope that another stop sign could also be installed at the intersection of Nani Kailua and Melelina Street, which would help deter the speeding at the top of the hill. Thank you for your assistance with this project. Sincerely, S RESPONSE 2 Date: Wed, 17 Sep 2003 Subject: 4 Way Stop at Nani Kailua Dr. & Kakalina St. Aloha, I live at the top of the Kailua View subdivision on Lulu Place. I am also a runner and make the big loop up Nani Kailua every evening. I mention this because you don't really get a good sense of traffic speed unless you walk or run along Nani Kailua. My conclusion ..... a significant number of people are driving at 45+ up and down that hill. As much as I dislike stop signs, I am total favor of adding more to this road. The most recent one has definitely slowed traffic, at least near vicinity of the sign. That's for people who stop. Others just run it. One of these days, a little kid is going to get zapped by some 45+mph idiot driver. P RESPONSE 3 Date: Sun, 21 Sep 2003 17:19:49 EDT Subject: 4 Way Stop at Nani Kailua Dr. & Kakalina St. Hi, Thank you for being interested in our input on this subject. I personally can see no improvement in the traffic problem since the sign went up. There is an increased noise level due to stopping and starting up on speed again. NOBODY drives at 25mph, not even police cars and the speeders speed before the stop sign and after. Also all the traffic signs on that corner are very unsightly (7 of them) and don't add to the look of this neighborhood. We are the second house from the corner on 75 -XXX Nani Kailua Dr. and are very unhappy. I would like to suggest speed humps as they were installed on Royal Ponciana Street in Kailua. EVERYBODY respects those. Mahalo, D RESPONSES 4 AND 5 Letters received from the Kailua View Estates Homeowners Association and Kona Heights Property Owner's Association (attached) RESPONSE 6 Date: Tuesday, December 23, 2003 6:41 PM Mr. Yamamoto: I am home owner on Hoene Street, one block from the 4 -way stop sign which was placed on Nani Kailua Drive, Kailua-Kona. I am writing to let you know that we are very pleased with the addition of the stop signs. This is a neighborhood of many families with children and the stop signs are beneficial in controlling the speed and flow of traffic in the area. Hoene Street is a long street that runs parallel to Nani Kailua Drive and additional stop signs on this street would also help the neighborhood deal with the increased, speeding traffic. Thanks for your attention to this matter. C RESPONSES OF THE KAILUA TRAFFIC SAFETY COMMITTEE INITIAL COMMENTS RECEIVED IN JANUARY 2004 MEMO SENT TO KONA TRAFFIC SAFETY COMMITTEE SUMMARIZING FINDINGS OF STUDY TO DATE AND REQUESTING THEIR INPUT. January 5, 2004 MEMORANDUM TO: KONA TRAFFIC SAFETY COMMITTEE CC: CASEY YANAGIHARA, COUNTY OF HAWAII DEPARTMENT OF PUBLIC WORKS FROM: WARREN M. YAMAMOTO, M&E PACIFIC, INC. SUBJECT: EVALUATION OF A FOUR WAY STOP AT THE NANI KAILUA DRIVE/KAKALINA STREET INTERSECTION This memorandum summarizes a draft report that was prepared by M&E Pacific, Inc., that evaluates the impact of a four way stop installed at the subject intersection. The purpose of this memorandum is to solicit comments from the Kona Traffic Safety Committee for inclusion in the final report. This memorandum does not include the conclusions of the report so as not to influence the opinions of the Committee members. The final report is expected to be delivered to the County Council at the end of January 2004. A major shortcoming in the evaluation was the County not providing traffic accident information. We understand the legal problems with this matter and the Committee should not "get after" the County for this. Prosect Background- A four way stop was installed at the intersection of Nani Kailua Drive and Kakalina Drive on July 24, 2003, in compliance with County of Hawaii Ordinance Number 03 37. The ordinance also required a licensed engineer to evaluate and make a report to determine if the improvement should remain. The evaluation included consultation with the Kona Traffic Safety Committee and the Hawaii County Department of Public Works. Discussion of Four Way Stops- Four way stops are generally implemented at intersections where traffic volumes have increased to the level where the minor street experiences excessive delay and are generally used as an interim measure until traffic signals can be installed. The Manual of Uniform Traffic Control Devices (MUTCD) has several guidelines and warrants for the implementation of four way stops. The four way stop was implemented at the subject intersection as a traffic calming device to control speeding in a residential neighborhood. Four way stops are not generally used as a traffic calming device for three major reasons: o Four way stops can increase delay on the major street to unacceptable levels; o Four way stops can increase the accident potential; and o Four way stops can cause drivers to speed on other portions of the road to make up for lost time. Evaluation Methodology- Three different sets of criteria were evaluated to determine the effectiveness of the four way stop: the evaluation criteria set forth in the MUTCD, its effectiveness as a traffic calming device, and public opinion as expressed by the Kona Traffic Safety Committee. The results of the evaluation are discussed in the next section. The MUTCD lists four primary criteria based on traffic volumes and accident experience to determine whether or not a four way stop is warranted. It also lists four optional criteria based on engineering judgment. A ten hour manual traffic count was taken at the intersection on September 9, 2003, to provide traffic volume data to measure against the warrants. The County did not provide traffic accident data for this study; therefore, only the two primary warrants utilizing traffic volumes could be evaluated. A field inspection determined that only one of the four optional warrants pertaining to controlling left turn conflicts could be evaluated. "Before and after" spot speed studies were conducted to determine if any changes in traffic speed on Nani Kailua Drive occurred as a result of the four way stop. The counts were taken on June 26, 2003, about a month before installation, and on August 28, 2003, about a month after installation. The members of the Kona traffic Safety Committee were contacted by email for their opinions at the start and near the completion of the study. Results of the Evaluation- The results for the three sets of criteria are discussed in the following paragraphs. With respect to the warrants listed in the MUTCD, neither of the two primary traffic volume -related warrants are met. There are not enough vehicles at the intersection to warrant either traffic signals or a four way stop. There are also not sufficient numbers of vehicles to cause left turn conflicts; therefore, the one optional criterion is not met. With respect to speed changes effected by the four way stop, the following table summarizes the "before and after" results: DOWNHILL RESULTS UPHILL RESULTS BEFORE AFTER BEFORE AFTER Number of samples 229 185 256 222 Average speed (mph) 32.6 28.8 30.8 26.0 Minimum speed (mph) 9 16 17 13 Maximum speed (mph) 55 57 44 52 <20 mph 4(2%) 5(3%) 4(2%) 12(5%) 20-30 mph 89(39%) 116(63%) 125(49%) 184(83%) 31-35 mph 72(31%) 44(24%) 80(31%) 20(9%) >35 mph 64(28%) 20(11%) 47(18%) 6(3%) There were 3.8 mile per hour (mph) and 4.8 mph decreases in average speed on the downhill and uphill directions of travel, respectively. Both of these differences are statistically significant at the 90% confidence level. The proportion of vehicles in the "20-30 mph" category also increased significantly, while the percentage in the "greater than 35" mph category decreased significantly, also. These changes indicate that the four way stop has had a dramatic impact on curbing speeding and has been very effective as a traffic calming device. However, the maximum observed speed did not decrease significantly. The maximum speed in the downhill direction was 55 mph or higher both before and after the four way stop installation. The maximum speed in the uphill direction increased from 47 mph to 52 mph. Two problems were noted. The data indicates that a diversion of traffic has occurred. County Department of Public Works staff said that they are receiving complaints from residents living on Aloha Kona Drive that there are more speeding cars on their street. During the 10 hour traffic count, the traffic counters reported 23 vehicles on Nani Kailua Drive running the stop sign, most at "full speed." This represents a hazardous traffic condition and is one reason multi -way stops are not used as traffic calming measures. With respect to the opinions of the Kona Traffic Safety Committee, five opinions were received to an initial email for comments. There were four opinions in favor of the four way stop and one not in favor. The dissenting opinion cited the unsightliness of the numerous sign posts and their opinion that drivers were speeding on other portions of the roadway to make up for lost time. Conclusions- TO BE COMPLETED AFTER RECEIVING INPUT FROM THE KONA TRAFFIC SAFETY COMMITTEE AND COUNTY OF HAWAII PUBLIC WORKS EMAIL DISTRIBUTION FROM ANN PETERSON TO COMMITTEE MEMBERS Date: Wednesday, January 07, 2004 1:00 AM Aloha and Happy New Year, Thanks for sending the study along. I forwarded it to the committee members and have been asked to put it on the agenda for our next meeting. Would you (Galen, Warren, others???) be able to attend? The meeting will be on February 24th, 5:00 PM at the Kealakehe Police Station. RESPONSES FOR COMMENTS ARE ON THE FOLLOW PAGES (Responses have been edited to remove personal identifying information) RESPONSEI Sent: Mon 1/5/2004 11:16 PM Subject: Re: Comments - 4 way stop, Nani Kailua & Kakalina In Kona topography, concentric wavy roads, i.e. those that follow pretty much along contour lines are conducive to geometrically superior and safe alignments. The parameters inhibiting prudently engineered roads are perplexing. The practice of retrofitting safety after poorly designed roads are in operation can be reversed if roads and communities are planned and developed with a combination of meaningful architecture and engineering. These should be done on the drawing board - not on the roads where there are injuries and deaths. 71 RESPONSE Sent: Monday, January 05, 2004 10:38 PM Subject: Comments - 4 way stop, Nani Kailua & Kakalina Dear Warren, Mahalo for your Before and After study of the 4 -way stop at Nani Kailua Drive and Kakalina Street. Those 23 vehicles running the stop sign at full speed makes for a very scarey situation and should strongly confirm why 4 -way stops are not meant for traffic calming. A better solution would be to place some slight curves in the road and to narrow each of the travel lanes to no wider than 10 feet. Place planters alongside the outer edges of the roadway to keep cars from running off the side of the road. The road is currently too wide and too straight which encourages cars to speed. J RESPONSE 3 AND SUBSEQUENT RESPONSE Sent: Tuesday, January 06, 2004 10:37 AM Subject: Re: Nani Kailua Drive/Kakalina Street 4 -way stop Although not "ideal" as a traffic calming device, according to the engineers, let's wait a bit and see what the final report says. If motorists are diverting to Aloha Kona, perhaps we should recommend that one or more 4 - way stops be placed there as well. Of course, reengineering Nani Kailua (and Aloha Kona) to install better traffic calming devices would be fine, but it would also take a lot of time and more money. The alternative to 4 -way stops on Nani Kailua and Aloha Kona, I fear, is no 4 -way stops on either, and no other traffic calming device. Given that probable choice, I pick the 4 -way stops. Jo Sent: Thursday, January 08, 2004 1:33 AM Subject: Re: Nani Kailua Drive/Kakalina Street 4 -way stop Yes Jo. Better then nothing. The county refuses to consider other traffic coming measures, such as speed bumps, round a bouts. My personal opinion is they don't want to spent the "dough" on us. I'm not alone in this feeling, per last nights road meeting. Aloha, T