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Home My WebLink AboutCOM 0227.017 1996-1998 STATE OF HAWAII DEPARTMENT OF TRANSPORTATION ~ MEMORANDUM r~ ~ .i DATE: July 28, 1997 TO: Mayor's Advisory Committee on Bicycling FROM: Mike Medeiros, Bicycle & Pedestrian Coordinator, HWY-T SUBJECT: Updating of Bicycle Design Information Comments: Over the last several years there has been an increase in the number of bicycle related projects that arc being undertaken. A review of the "Statewide Uniform Design Manual for Streets and Highways, Section 16, Bicycle Facilities" revealed that some of the information is outdated. Consequently, many designers have been using the AASHTO "Guide for the Development of Bicycle Facilities" in lieu of Section 16. With this in mind an update to Section 16 has been drafted which incorporates the current information from the AASHTO bicycle guide and other reference sources. Please review the enclosed draft and comment accordingly. [f you have any questions, please contact Mike Medeiros at 587-232 L Your comments would be appreciated by August I5, 1997. Thank you for your attention to this matter. Comma. DIa • ~ File Iin. tSLI. presented. Ref. 20:_~ ~ Re4_ Date ETA-T~a.~,~~ ~~r1=o~~ ~~sr~aV M?~~~u~4L, cinttcnnMrcnnourcrvr..wro ~ ~ ~S ~ t{lC~~l`F~ June 3, 1997 ~ s DRAFT SECTION 16. BICYCLE FACILITIES 16-1 ENERAL The bicycle is recognized as a viable mode of transportation. By State law bicyclists have the same rights and obligations as other roadway users. As such it is necessary to follow established transportation planning and engineering principals in order to design and produce bikeways and bike facilities that will best serve the public. Every street and highway on which bi'Cycles are permitted to operate is a "bicycle street" and should be designed and maintained to accommodate shared use by bicycles and motor vehicles. 16-2 DEFINITIONS AND TERMS 1. Bicvcle: A vehicle having two tandem wheels, either of which is more than 16 inches in diameter or having three wheels in contact with the ground any of which is more than 16 inches in diameter, propelled solely by human power, upon which any person or persons may ride. 1. Design Bicvclis(.c: Roadway treatments intended to accommodate bicycle use must address the needs of both experienced and less experienced riders. "Bike Plan Hawaii, 1994" has adopted the following classification system for bicycle users; • Group A -Advanced Bicyclists. These arc experienced riders who can operate under most traffic conditions. The Bicycle Federation of America estimates that fewer than 5 percent of bicyclists would qualify as Group A riders. • Group B -Basic Bicyclists. These aze casual or new adult and teenage riders who are less confident of their ability to operate in traffic without special provisions for bicycles. • Group C -Children. These are pre-teen riders whose roadway use is initially monitored by parents. Eventually they are accorded independent access to the bikeway system. 3. Bike Facilities: A general term denoting improvements and provisions made to accommodate or encourage bicycling, including parking facilities, mapping all bikeways, and shared roadways not specifically designated for bicycle use. " 4. Bikew+avr: Any road, street, path, or way which in some manner is specifically designated as being open to bicycle travel, regardless of whether such facilities are designated for the exclusive use of bicycles or arc to be shared with other transportation modes. 5. Bike Lane: A portion of a roadway which has been designated by stripping, signing and pavement markings for the preferential or exclusive use of bicyclists. h. Bike Path: A bikeway physically separated from motorized vehicular traffic by an open space or barrier and either within the highway right of way or within an independent right of way. 7. Bike Route: A roadway designated as part of the bikeway system with appropriate informational and directional markers that is shared by motorist and bicyclist. 8. Wide outside lame: An outside, shared lane that accommodates both motorists and bicyclists. It is between 14 ft. and 16 ft. wide. 9. Shared Lane or• Roadwav: Any roadway upon which a bicycle lane is not designated and which may be legally used by bicycles regardless of whether such a facility is specifically designated as a bikeway. 2 10. Right of Wuv: (a) A general term denoting land, property, or interest therein, usually in a strip, acquired for or devoted to transportation purposes. (b) The right of one vehicle or pedestrian to proceed in a lawful manner in preference to another vehicle or pedestrian. 11. Bike Shed: An area or location which can be considered a terminal for generating and ending bicycle trips. Examples of bike sheds arc communities, parks, schools, or malls. /l. 6icvcle Ji•iendly ~onec: Areas that are blanketed with a complete set of bicycle facilities. It is possible to travel and park, via bicycle, everywhere in these woes on safe, coAvenient, integrated, and secure facilities. ¦ 16-3 DESIGN ELEMENTS The principal variables affecting design treatments for bicycles arc the design bicyclist, the type of roadway project involved, and traffic operation factors. I . The dcsigm bicyclist. The recommended roadway design treatments and widths to accommodate bicyclist should be based on Group B/C riders. The minimum design for any roadway on which bicycle use is permitted should be based on Group A riders. 2. The type of roadway project involved on the selected route. New construction and reconstruction projects generally have more favorable right-of--way considerations for accommodating bicycle traffic. On other projects the design improvements must be incorporated into existing geometries or right-of- way widths. 3 3. Traffic operations factors. The most significant factors for determining the appropriateness of various design treatments are; (a) traffic volume, (b) average motor vehicle operating speed, (c) traffic mix, and (d) number of intersections and entrances. (a) Traffic volume. Higher motor vehicle traffic volumes represents greater potential risk for bicyclists and the more frequent overtaking situations are less comfortable for group B/C riders unless special design treatments are provided. (b) Traffic speed. The average operating speed or running speed is more important that the posted speed limit, and better reflects actual conditions encountered by bicyclists. Motor vehicle speed has a negative impact on risk and comfort ofbicyclist unless mitigated by special design treatments. Five ranges of average speeds are used: - Less than 20 mph - 20 to 30 mph - 31 to 40 mph - 41 to 50 mph - Over 50 mph (c) Traffic mix. The regular presence of trucks and buses (i.e. approximately 30 per hour or more) can increase risk and have a negative impact on the safety and comfort of bicyclists. At high speeds, the wind blast from such vehicles create a serious risk of falling for bicyclists. Even at lower speeds most bicyclist prefer several feet of separation between themselves and these large vehicles. Many bicyclist will choose a different route or not ride at all where there is a regular presence of such traffic. (d) Intersections. When bike lanes are used special attention must be given to the merging and turning movements ofthe bicycles and motor vehicles. AASHTO provides guidelines for bike lanes through intersections. These are shown in Figures 1 and 2. Another consideration is the number or r`IP Ped. Crossing Ped. Crossfnq ~ aotlona Daalva strge. ~ %IJVC J {'MIN. ~4 pW~~d I KIr gIOCO la ~I rhara a W^0 r<Ol+t - I INIaJ wahbiw Edbb faro Ions! ~ ~1' MIM axlet. I ~ I ~ 1 Tydoa Dom or rhrolpn bloydst, %H apoca la wdobla. I ~ r l ahp~ F O'aDDaG Ot l ? I ~ al wa: IK~ RIGHT-TURN-ONLY LANE PARKING LANE BECOMES RIGHT-TURN-ONLY LANE lNOr to Scale) flletr lc Conveys long I Ft. 0.3 n>.) Ped. Crossing Petl. Crossing TYDIW Dom o} % ' I 1 HYOU()11 blcydar. WQ s'rl TYDIOaI psm of ttrough bloydlat. \ I~ % If spaw le 1 wdmN4 1 I \ ~ UI'OD bha Nlns aMD rhers ' ~ I ~ I ~ ~ I ~ I rlghr turn arty daWpmra4 I~ OPTIONAL DOUBLE RICHT LANE BECOMES RIGHT-TURN-ONLY LANE RIGHT-TURN-ONLY LANE Figure 1 Bicycle Lanes ApproachingMator Vehicles Right-Turn-Only Lanes. 5 " PEDESTRUIN CROSSING " Rk7RWlE j~r ~ y RUST ~ylAuhl IDRM RIGHT 7 scat t i[U N MILS i i i i t i i i i w z 5 5 Z a ~ <y x ~ a m Figure 2. Bike Lane Approaching an intersection with Throat Widening b frequency of intersection along a bike route The ability to ride continuously with a minimum amount of stops is an important consideration to bicyclist when choosing a route. Through traffic should be directed in favor of the bicycle route as much as possible to minimize the amount of stopping encountered by bicyclists. Once the principal variables affecting the bikeway design have been identified, five basic types of facilities arc used to accommodate bicyclist; shared lanes, wide outside curb lanes, bike lanes, bike paths, and shoulders. Figures 3 & 4provide across-section of these type of facilities. Table 1 through Table 6 present the recommended roadway design treatments and widths to accommodate bicycles. There arc separate tables for Group A and Group B/C riders.•'Additionally, there are separate tables for two basic type of roadway sections: urban-with curb and gutter, and rural-without curb and gutter. These tables indicate the appropriate design treatment given various sets of traffic operations and design factors. The desigmer is reminded that the desirable design treatments should be based on Group B/C riders. The minimum design treatments will only accommodate a small portion, approximately 5%, of the bicycle riding population, the Group A riders. These minimums should be used only when all other possible solutions have been exhausted. ~ F 3.1 Drainage rates Drainage grate inlets and utility covers are potential problems to bicyclists. When a new roadway is designed, all such grates and covers should be kept out of bicyclists' expected path. On new construction where bicyclists will be permitted, curb inlets should be used wherever possible to completely eliminate exposure of bicyclists to grate inlets. [t is important that grates and utility covers be adjusted flush with the surface, including after a roadway is resurfaced. Parallel bar drainage grate inlets can trap the front wheel of a bicycle causing loss of steering control and, often, the bar spacing is such that they allow narrow bicycle wheels to drop into the grates, resulting in serious damage to the bicycle wheel and frame and/or injury to the bicyclists. These grates should be replaced with bicycle-safe and hydraulically efficient ones. When this is not Shared lane -urban No specific accommodations for bicycles. Motorists and bicyclists share roadway "as-ia". I I Sidewa0c IAIIIAIAIIIAIAIIIIIIIAIIIaaIIIIIAIAIIIAaAIIIAIAIhIIIIAIAIIIAIAIIIIAIIAIlANI1111UAIIlAAAIII SidA' ewag Standud Ime ~ Stendud lase I Wide outside curb lane ~ I 14 ft.-16 ft. ~ 14 ft.-16 ft. Sidewalk AIIIAIIIIIlII11111111A1I11AAlAlIAIIAIII IIIIAIIIIIAlAlI111AlIIIIlA~1111AlAlIIAIIIIIIIIAIIIIIAI IIIIIIIAAIIIAIIUIIAIAIIIIAIIAIIgIIAIII Sidcwalk Widc curb leuc Stmdud ~ Standard Widc curb lanc lase ~ Imc I i Bike Path 2 ft l2 ft. preferred 2 ft. t'tt ttt ttl ttt ttt ~t IIIIIAIAIIIAIAIIIII11111111AlIIIIIAAIIIIlAlI111flI1flIlIIIAIIIIIIIIAIIIANIIIIAIlllll It ttl tll Itt ttl tlt t Paved Trsvclway Graded ahouldcr Graded shoulder ~iCiU~IIC g ca) CURBED STREET WITH PARKING 8'-10' ~ ~ I. I. 8'-10' Porkln9 Btke Motor Vehlde Lanea "'III"` gee III"` Parkltp ~ lone Lone (b) CURBED STREET WITHOUT PARKING ~7~ ~ way y Motor VehlCle lanes Bike Btke Lane Lane cc) STREET OR HIGHWAY WITHOUT CURB OR GUTTER Shoulder _ Shoulder Motor Vehicle Lanes Bike Bike Lane lane INOt to Scale) ' Figure y Typical Bicycle Lune Cross Sections. 1 Table 1. Group B/C bicyclists, urban section, no parking lavers a annual dail traffic AADT volume less than 3,000 3,000 to 10,000 over 10,000 average motor trucks & truck & trucks & vehicle operating cars only bus ~ cars only bus ~ cars only bus s eed less than 20 mph sl ~ we 14 we 14 we 15 we 16 bl 5 20 to 30 mph we 14 I we i6 we i6 I bl 5 ~ bl 5 ~ bl 6 31 to 40 mph bl 5 i bl 5 i bl 5 bl 6 'i bl 6 II bl 6 41 to 50 mph bl 5 bl 6 ~I bl 6 I bl 6 bl 6 I by over 50 mph bt6 ~'I by by ! by by ~ by ,r Key: we =wide curb lane" sl =shared lane bl =bike lane"` sh =shoulder by =bike path j ~ 'ISee page 2 for definitions ";wc numbers represent usable widths, in feet, of outer lanes measured from lane ,stripe to edge of gutter pan. If no gutter pan is provided, add 1 ft. minimum for shy ,distance from curb. "",bl numbers represent width, in feet, from edge of gutter pan. If no gutter pan is provided, Ibl numbers may be taken from face of curb. truck & bus =approximately 30 per hour I I j ~ I I sheet i ~imsexcell.bkibn Page 10 Table 2. Group B/C bicyclist, urban section, parking ~'avera a annual dail traffic AADT voulume less than 3,000 3,000 to 10,000 over 10,000 average motor trucks & ! truck & trucks & vehicle operating cars only j busses cars only i busses I cars only ; buses s eed less than 20 mph we 14 I we 15 I we 14 ~'i we 15 j bl 5 bl 5 20 to 30 mph we 15 ~ we 16 I we 16 bl 5 j bl 5 ~ bl 6 31 to 40 mph bl 5 bl 5 bl 5 ~ bl 6 bl 6 bl 6 41 to 50 mph bl 6 ~ bl 6 bl 6 by by by over 50 mph by ~ by by by % by I by i Ke ~wc =wide curb lane" sl =shared lane bl =bike lane"" sh =shoulder by =bike path y ' See page ~2 for definitions "li we numbers represent useable widths, in feet, measured from lane stripe to left edge of I, the parking space. bl numbers represent width, in feet, from edge of gutter pan. If no gutter pan is provided, bl numbers may be taken from face of curb. I truck & bus =approximately 30 per hour sheet 3~I msexcell.bktblt i Page 11 Table 3 Group B/C bicyclists, rural section avera a annual dail traffic AADT voulume less than 3,000 3,000 to 10,000 over 10,000 average motor trucks & truck & trucks & vehicle operating cars only I bus ;cars only ' bus cars only bus s eed less than 20 mph sh 4 sh 4 sh 4 sh 6 sh 6 sh 6 20 to 30 mph sh 4 ~ sh 4 ~ sh 4 ~ sh 6 sh 6 sh 8 31 to 40 mph sh 4 i sh 6 sh 4 sh 6 sh 6 sh 8 41 to 50 mph sh 6 i sh 8 sh 6 sh 8 sh 8 sh 8 over 50 mph sh 6 sh 8 sh 8 sh 8 sh 8 sh 8 K@y. we =wide curb lane"` sl =shared lane bl =bike lane"` sh =shoulder by =bike path ''See page 2 for definitions ",wc numbers represent usable widths, in feet, of outer lanes measured from lane stripe to edge of gutter pan. If no gutter pan is provided, add 1 ff, minimum for shy distance from curb. bl numbers represent width, in feet, from edge of gutter pan. If no gutter pan is provided, bl numbers may be taken from face of curb. truck & bus =approximately 30 per hour sheet 4,msexcelLbktbll Page 12 s Table 4. - Group A bicyclists, urban section, no parking avera a annual dail traffic AADT voulume less than 3,000 3,000 to 10,000 over 10,000 average motor trucks & truck & trucks & vehicle operating cars only bus 'cars only bus cars only bus seed less than 20 mph sl sl sl we 15 we 14 we 16 20 to 30 mph sl sl we 14 we 15 we 15 we 16 31 to 40 mph we 14 we 14 we 14 we 15 we 15 bl 4 41 to 50 mph we 15 we i6 bl 4 bl 5 bl 5 bl 6 over 50 mph bl 5 bl 5 bl 5 bl 6 bl 6 bl 6 Key:* we =wide curb lane" sl =shared lane bl =bike lane"' sh =shoulder by =bike path ',See page 2 for definitions we numbers represent usable widths, in feet, of outer lanes measured from lane stripe to edge of gutter pan. If no gutter pan is provided, add 1 ft. minimum for shy distance from curb. bl numbers represent width, in feet, from edge of gutter pan. If no gutter pan is provided, bl numbers may be taken from face of curb. truck & bus =approximately 30 per hour sheet 2. msexcell.bktbn Page 13 • Table 5. Group A bicyclists, urban section, with parking i lavera a annual dail traffic AADT voulume i less than 3,000 3,000 to 10,000 over 10,000 average motor trucks & I truck & trucks & vehicle operating cars only I bus cars only I bus cars only ~ bus s eed less than 20 mph sl sl sl sl sl we 14 20 to 30 mph we 14 ~ we 14 I we 14 i we 14 we 15 j we 15 31 to 40 mph we 14 i we 15 it we 14 Ii we 15 I we 15 it bl 4 41 to 50 mph we 15 we 16 bl 4 ~ bl 5 bl 5 i bl 6 over 50 mph bl 6 bl 6 ' bl 6 by by by Key:* iwc =wide curb lane" sl =shared lane bl =bike lane`"' sh =shoulder by =bike path " See page 2 for definitions we numbers represent useable widths, in feet, measured from lane stripe to left edge of the parking space. bl numbers represent width, in feet, from edge of gutter pan. If no gutter pan is provided, ~ bl numbers may be taken from face of curb. truck & bus =approximately 30 per hour sheet 5'~. msexcell.bk[blt Page 14 0 Table 6. Group A bicyclists, rural section I I avera a annual dail traffic AADT voulume I ~ less than 3,000 I 3,000 to 10,000 over 10,000 average motor trucks & truck & !trucks & vehicle operating cars only ~ bus I cars only i, bus cars only i bus s eed ~ I less than 20 mph sl sl ~ sl sl sl sh 4 20 to 30 mph sh 4 I sh 4 sh 4 sh 4 sh 4 !~i sh 4 31 to 40 mph sh 4 ~ sh 4 ~ sh 4 sh 4 sh 4 ~ sh 6 41 to 50 mph sh 4 ~I sh 4 i sh 4 ~ sh 6 sh 6 sh 8 over 50 mph sh 4 I sh 4 ~i sh 6 sh 8 i sh 8 sh 8 K@y. Iwc =wide curb lane" sl =shared lane bl =bike lane"' sh =shoulder by =bike path I ~ i ~ i `~iSee page 2 for definitions I, "'~,wc Numbers represent usable widths, in feet, of outer lanes measured from lane istripe to edge of gutter pan. If no gutter pan is provided, add 1 ft. minimum for shy distance from curb. ~ ~ bl numbers represent width, in feet, from edge of gutter pan. If no gutter pan is provided, Ibl numbers may be taken from face of curb. ' (truck & bus =approximately 30 per hour i ~ I 'i i I sheet 6 msexcell.bktblt I ~ Page 15 0 immediately possible, consideration should be given to welding steel cross straps or bars perpendicular to the parallel bars to provide a maximum safe opening between straps. This should be considered a temporary con•ection. While identifying a grate with a pavement mazking would be acceptable in some situations, as indicated in the MUTCD, parallel bar grate inlets deserve special attention. Because of the serious consequences of a bicycle missing the pavement marking in the dazk or being forced over such a grate inlet by other traffic, these grates should be physically corrected, as described above, as soon as practicable after they are identified. 16.3.2 Pavements The quality of the bikeway pavement should be the same as that of the motor vehicle travelway. Pavement surface irregularities can do more than cause an unpleasant ride. Gaps between pavement slabs or drop offs at overlays pazallel to the direction of travel can trap a bicycle wheel and cause loss of control; holes and bumps can cause bicyclist to swerve into the path of motor vehicle traffic. On older pavements it may be necessary to fill joints, adjust utility covers or, overlay the pavement to make it suitable for bicycling. 16 3 3 Traffic Control Devices At intersections where bicycle traffic exists or is anticipated, bicycles should be considered in the timing of the traffic signal cycle, as well as the traffic detection device. Nomtally, a bicyclist can cross an intersection under the same signal phasing arrangement as motor vehicles; however, on multi-lane streets special consideration should be given to ensure that short clearance intervals are not used. If nccessazy, an all-red clearance interval may be used. To check the clearance interval, a bicyclist's speed of 10 mph and a perception/rcaction/braking/ time of 2.5 seconds should be used. Detectors for traffic-actuated signals should be sensitive to bicycles and should be located in the bicyclist's expected path, including left turn lanes. [n some situations, the use of pedestrian actuated buttons may be a preferred alternative to the use of detectors provided they do not require bicyclist to dismount or make unsafe leaning movements. Where programmed ~6 visibility signal heads are used, they should be checked to ensure that they arc visible to bicyclist who are properly positioned on the road. 163.4 igning and Marlting The MLJ'I'CD should be consulted for guidance on signs and pavement markings. Where bicyclists are expected to use different routings from motorists, directional signing should be used to guide bicyclists along the special routing. ¦ 16-4 BIKE PATHS " Bike paths are facilities on exclusive rights-of--ways which have minimal cross flow by motor vehicles. They can be thought of as freeways for bicycles and can serve both transportation and recreational functions. The design of bike paths includes many of the same principals used in the design of roadways; design speed, stopping sight distance, horizontal curves, grades, etc. AASHTO's "Guide for the Development of Bicycle Facilities, 1991" provides the basis for the following information, When atwo-way path is constructed parallel to an existing roadway the minimum recommended separation is 5 feet. Careful consideration must be given to the following; 1. The lane of bicycle travel that is travelling against motor vehicle traffic. Wrong way travel by bicyclists is a major cause of bicycle/automobile accidents and should be mitigated at every opportunity. 2. Exit and entrance points. When a bike path ends bicyclists going against traffic will tend to continue to travel on the wrong side ofthe street. Likewise, bicyclists entering a bike path will often travel on the wrong side of the street in getting to the path. ~7 3. Intersections. At intersections, motorist entering or crossing the roadway will not notice bicyclists coming from their right, as they are not expecting contra-flow traffic. 4. Bicyclists using the path generally are required to stop or yield at all cross streets and driveways, while bicyclists using the roadway usually have priority over cross traffic. The frequent stopping at the cross streets may cause bicyclists to avoid using the path and take to the street in order to gain a less interrupted route When the distance between the edge of the roadway and bicycle path is less than 5 feet, a suitable physical divider may be considered. Where used, the divider should be a minimum of 4.5 feet high, to prevent bicyclists from toppling over it, and should be designed so that it does not become an obstruction itself. 16-4.1 Widths Two way bike paths should be a minimum of 10 feet wide. Where possible paths should be 12 feet wide to accommodate mix use with pedestrians. 8 foot wide paths are not recommended because once the paths are built they invariably become multi-use paths. Walkers, joggers, skaters, skateboarders, and bicyclists will use the paths at the same time and an 8 foot width will not be adequate. The minimum width of a one~irectional bicycle path is 5 feet. It should be recognized, however, that one-way paths often will be used as two-way facilities unless effective measures are taken to assure on-way operation. Without such enforcement, it should be assumed that bicycle paths will be used as two-way facilities and therefore designed accordingly. 16.4.2 Clearances A minimum 2 feet, with 3 feet preferred, should be maintained as lateral clearance to provide clearance from trees, poles, walls, signs, fences, guard rails, and other obstructions. For overhead obstructions a clearance of R feet minimum should be provided with l0 feet preferred. 16-4 3 Design Soeed Many factors affect the speed at which the bicyclists travels. These include wind, grade, purpose of the trip and condition of bike path. Bicycle paths should be designed for speeds achievable by the faster bicyclists, Group A. In general a minimum design speed of 20 mph should be used; however, when the grade exceeds 4 percent, oc where strong prevailing tail winds exist, a design speed of 30 mph should be used. 16-4 4 Horizontal Alignment and Superelevation The minimum radius of curvature negotiable by a bicycle is a function of the Superelevation rate of the bicycle path surface, the coefficient of friction between the bicycle tires and the bicycle path surface, and the Speed of the bicycle. The minimum design radius of curvature can be derived from the following formula: R= V z l5 (e+~ where: R =Minimum radius of curvature (ft) V =Design Speed (mph) e = Rate of superclevation f = Coefficient of friction For most bicycle path applications the superclevation rate will vary from a minimum of 2 percent (the minimum necessary to encourage adequate drainage) to a maximum of approximately five percent (beyond which maneuvering difficulties by slow bicyclists and adult tricyclists might be expected). The minimum superclevation rate of 2 percent will be adequate for most conditions and simplifies construction. l9 The coefficient of friction depends upon speed; surface type, roughness, and condition; fire type and condition; and whether the surface is wet or dry. Extrapolating from values used in highway design, design friction factors for paved bicycle paths can assumed to vary from 0.30 at I S mph to 0.22 at 30 mph. TABLE 7 Minimum Radii for Bicycle Paths (e = 2 peroen[) Design Speed-V (mph) Friction Factor-f Minimum Radius-R (feet) 20 0.27 95 25 0.25 155 30 0.22 250 35 0.19 390 40 0.17 565 When less than minimum radius curves must be used on bicycle paths because of right of way, topographical or other unavoidable restrictions, standard curve warning signs and supplemental markings should be installed in accordance with the MUTCD. The negative effects of less than minimum curves can also be partially off set by widening the pavement through the curves. 16-4 5 Grade A level bikeway is preferred by nearly all bicyclists, therefore, grades on bicycle paths should be kept to a minimum. Grades greater than 5 percent arc undesirable because the ascents arc difficult for many bicyclists and the descents may cause some bicyclists to exceed the speeds at which they are competent. However, where terrain dictates, grades over 5 percent arc acceptable when sufficient right-of--way and funding for additional design treatments are available. 20 16-4 6 Stooping Sight Distance To provide bicyclists with an opportunity to sec and react to the unexpected, a bicycle path should be designed with adequate stopping sight distances. The distance required to bring a bicycle to a full controlled stop is a function of the bicyclist's perception and brake reaction time, the initial speed of the bicycle, the coefficient of friction between the tires and the pavement, and the braking ability of the bicycle. Figure 5 indicates the minimum stopping sight distance for various design speeds and grades based on a total perception and brake reaction time of 2.5 seconds and a coefficient of friction of 0.25 to account for the poor wet weather braking characteristics of many bicycles. For two-way bicycle paths, the sight distance in descending direction, that is, where "G" is negative, will control the design. Figure 6 is used to select the minimum length of vertical curve necessary to provide minimum stopping sight distance at various speeds on crest vertical curves. The eye height of the bicyclists u assumed to be 4.5 feet and the object height is assumed to be zero to recognize that impediments to bicycle travel exist at pavement level. Figure 7 indicate the minimum clearance that should be used to line of sight obstructions for horizontal curves. The lateral clearance is obtained by entering Figure 7 with the stopping sight distance from Figure 5 and the proposed horizontal radius of curvature. Bicyclists frequently ride abreast of each other on bicycle paths and, on narrow paths bicyclists have a tendency to ride near the middle of the path. For these reasons, and because of the serious consequences of a head on bicycle accident, consideration should be given to widening the path through the curve, installing a yellow center stripe, installing a curve warning sign in accordance with the MUTCD , or some combination of these alternatives. 16-4 7 Intersections Intersections with roadways arc important considerations in bicycle path design. If alternate routes for a bicycle path are available, the one with the most favorable intersection conditions should be Zl G~ zo i I5 sl F I >r l y t 0 1 r 2h r v ~1 I~ Iti°~ 1~ _ o~ I 1 t o ~ ~ I 1 1~ 1~ 5 1 1 1 \ 1 \ \ 0 0 50 ti 100 150 200 250 300 350 400 ' 5 = Minimum Stappinp Distance - Ft, _ vz 5 30(trG> 13.67 V Where: 5 = Uin)mum 5)ght Diatcnce, Ft. Dacend l-G) v = Velocity, mDh Ascend I+GI - - - - t = Coefficient of friction luae 0.25) G = Grcde Ft?Ft, Irise/run) (Herr le Converslon~ I ft. 0.3 m, 1 mph I.6 km/hl Figure rj Minimwn Stopping Sight Distances. 22 tool +~)Z L = 25- A when 5>L L , A52 when 5<L 1001 ?~)Z LYIN 2V 500 s = stODDinq Sight Dletanae Ift.) A = Algebraic Difference In• Crade LL h~ =Eye Height of Blcyycllat 14.5 Feef> hZ= Height of Oblect 10 Faet) L = Alinimum Vertical Curve Length Ift.) L 400 t c° J M V 300 ,yh - s e~ U t ~ ~ 200 E 2 ` ~a5 mph S 100 S~~ ~ ~ \ v=w mph 0 5 10 15 20 25 Algebraic Difference In Crade IA) Figure (r> Minimum Length of Vertical Curves. 23 Sight distance lSI measured along this Ilne 5 = Sight distance In feet. R = Radius of Q. Inside lane In feat. m .Distance from ~ Inside lone to feet. V =Design speed for 5 In mph Angle Is expressed In degrees i~ ln9~Qe lane~~ , ~ fff / Ir / 28.655 Eye ~Llne of Sight Oblec m ° R I verb ` R i N Obstruction or S R CCOS~ 1 RR Cutbank 28.65 Line of eight Is 2.0' above 4. Inside Formula applies only when S Is bna at point of obstruction. equal to or less than length of curve. f ~ 40 0 . a ~ N ryy E ° a eI, N b 30 4 ~ ~a $ a`'`'o 0 20 yl eye 6 s b e u 10 0 u 5 IOQ 200 300 0 0 J Sight Olstance t5) -feet (Aletr lc Converslon~ I Ft. 0.3 m.I + Lotaral Gaorancea on horizontol curves should be calcubted based on the sum of the stopping sight distances for bicyclists travelling in opposite directlOns around the curve. See text for addltlOnal dlsCUSSIOn. Figure "7 Minimum Lateral Clearances on Horizontal Curves. 24 selected. When intersections occur at grade, a major consideration is the establishment of right of way. The type of traffic control to be used (signal, stop sign, yield sign, etc.), and location, should be provided in accordance with the MUTCD. It is preferable that the crossing of a bicycle path and a highway be at a location away from the influence of intersections with other highways. Controlling vehicle movements at such intersections is more easily and safely accomplished through the application of standard traffic control devices and normal Rules of the Road. At crossings of high volume multi-lane arterial highways where signals are not warranted, consideration should be given to providing a median refuge area for bicyclists. When bicycle paths terminate at existing roads, it is important to integrate the path into the existing system of roadways. Care should be taken to properly design the tcrminals'to transition the bicycle traffic into a safe merging or diverging situation. Appropriate signing is necessary to warn and direct both bicyclists and motorists regarding these situations. Bicycle paths intersections and approaches should be on relatively flat grades. Stopping sight distances at intersections should be checked and adequate warning should be given to permit bicyclists to stop before reaching the intersections, especially on down grades. 16 4 7 ~~~ne and Markine Adequate signing and marking are essential on bicycle paths, especially to alert bicyclists to potential conflicts and to convey regulatory messages to both bicyclists and motorists at highway intersections. Figure 8 shows sign placement location for bike paths. It should be noted that when a bike facility is to be shared with motorist, such as a bike lane, sign placement should be as specified in the MUTCD, Part II. 2s 8 ft max 7ftmin 2ftmin 6 ft. max ~....4w.. B ik e P ath Figure g A designer should consider a 4 inch wide yellow centerline stripe to separate opposite directions of travel. This is particularly beneficial in the following circumstances: for heavy volumes of traffic, on curves with restricted sight distance, and on unlighted paths where nighttime riding is expected. Edge lines are also beneficial where nighttime bicycle traffic is expected or where there is a drop off or significant slope change due to a gutter or Swale. 2fo Care should be exercised in the choice of pavement marking materials. Some marking materials are slippery when wet and should be avoided in favor of more skid resistant materials. 16-4.8 Drainaee The recommended minimum pavement cross slope of 2 percent adequately provides for drainage. Sloping in one direction instead of crowning is preferred and usually simplifies the drainage and surface construction. A smooth surface is essential because, unlike an automobile, a bicycle does not have a separate suspension system to absorb the shocks and bounces. Any roughness and unevenness pass directly to the bicyclists arms and legs which cause fatigue and possibly injury. ¦ 16-5 SUPPLEMENTAL FACILITIES Providing bicycle parking facilities is an essential element in the overall design of a bikeway. People are discouraged from bicycling unless adequate parking is available. Bicycle parking facilities should be provided at both the trip origin and trip destination and should offer protection from theft and damage. Facilities should be very convenient and be near building entrances or other highly visible areas which arc self policing. If bicycle parking is not property designed and located, bicyclists will use trees, railings, and other available appurtenances. This practice can damage the appurtenances and create an obstruction for pedestrians. In addition to bicycle parking facilities, other improvements that complement bikeways should also be considered. For example, on long, uninterrupted bicycle paths, turnouts or rest areas may be provided, also emergency telephones could be considered. 27 REFERENCES: 1. Bike Plan Hawaii, State of Hawaii Master Bike Plan. Updated September 1994 2. AASHTO'S Guide for the Development of Bicycle Facilities, 1991 3. Selecting Roadway Design Treatments to Accommodate Bicycles, 1994, FHWA -RD-92-073 LIST OF FIGURES Fig.#1 Turn Lanes Fig. #2 Turn Lanes Fig. #3 Cross Sections Fig. #4 Cross Sections -Bike lane Fig. #5 Minimum Stopping Sight Distance Fig. i~6 Minimum Length of Vertical Curve Fig. #7 Minimum Lateral Clearance - Horizontal Curve Fig. #8 Sign Location for Bike Paths LIST OF TABLES: Tbl. # 1 B/C Riders, Urban, No Parking Tbl. #2 B/C Riders, Urban, Parking Tbl. #3 B/C Ridcrs, Rural Tbl. #4 A Riders, Urban, No Parking Tbl. #5 A Riders, Urban, Parking Tbl. #6 A Riders, Rural 28