Chapter 4 - Sidewalk Design Guidelines and Existing Practices - Sidewalks - Publications - Bicycle and Pedestrian Program - Environment. Driveway crossings permit cars to cross the sidewalk and enter the street, and they consist of the same components found in curb ramps. It is the driver's responsibility to yield to the pedestrian at the driveway–sidewalk interface. Intersections of driveways and sidewalks are the most common locations of severe cross- slopes for sidewalk users. Some inaccessible driveway crossings have cross- slopes that match the grade of the driveway because a level area is not provided for the crossing pedestrian. This type of crossing can be very difficult for people who use wheelchairs or walking aids (Figure 4- 3. Rapid changes in cross- slope usually occur at driveway flares and are most problematic when they occur over a distance of less than 0. As the wheelchair moves over the surface of a severely warped driveway flare, it will first balance on the two rear wheels and one front caster. As the. Wide sidewalks can be designed similar to sidewalks with a setback if the upper portion of the sidewalk is leveled for pedestrians and the bottom portion is sloped for automobiles (Figure 4- 3. A level landing area can be achieved on narrow sidewalks if the sidewalk is jogged back from the street as it crosses the driveway (Figure 4- 3. Purchasing additional land to jog the sidewalk back should be strongly considered when there is not enough space for a level sidewalk. Similar to a parallel curb ramp, a parallel driveway crossing provides a level landing by lowering the sidewalk to the grade of the street (Figure 4- 3. This design is preferable to the severe cross- slopes at some driveway crossings, but it is not as easy to negotiate as setback and wide sidewalk designs. With this type of crossing, drivers assume that they can speed up on the level portion next to the street. In addition, the parallel ramp can produce steep grades on both sides of the driveway and initiate drainage problems on the landing. Commercial districts with front parking between the sidewalk and the buildings are often designed with a series of individual lots with individual entrances and exits (Figure 4- 3. This design increases the number of driveway crossings and forces pedestrians to encounter automobiles repeatedly. If the driveway crossings do not have level landings, people with mobility disabilities must also repeatedly negotiate severe cross- slopes. To improve access for all pedestrians,including pedestrians with mobility disabilities, individual parking lots should be combined to reduce the number of entrances and exits. The remaining driveway crossings should be retrofitted to include level landings (Figure 4- 3. Medians and islands help pedestrians cross streets by providing refuge areas that are physically separated from the automobile path of travel. A median separates opposing lanes of traffic. An island is a protected spot within a crosswalk for pedestrians to wait to continue crossing the street or to board transportation such as a bus. Medians and islands are useful at irregularly shaped intersections, such as where two roads converge into one (Earnhart and Simon, 1. Medians and islands reduce the crossing distance from the curb and allow pedestrians to cross during smaller gaps in traffic. Examples of cut- through medians and ramped and cut- through islands are shown in Figure 4- 3. Medians and islands are useful to pedestrians who are unable to judge distances accurately. Medians and islands also help people with slow walking speeds cross long intersections with short signal cycles. Because medians and islands separate traffic into channels going in specific directions, they require crossing pedestrians to watch for traffic coming in only one direction. According to ADAAG, a raised island or median should be level with the street or have curb ramps at all sides and a level area 1. If a cut- through design is used, it should be at least 0. Cutthrough medians are easier for wheelchair users and other people with mobility impairments to negotiate than ramps. In addition, the edge of a cut- through can provide directional information to people with visual impairments. However, if the cut- through is too wide, people with visual impairments might not detect the presence of a median or island. For this reason,the width of the cut- through should be limited to ensure detection by people with visual impairments. A detectable warning on the surface of the cut- through will also improve detectability. Crosswalks are a critical part of the pedestrian network. A crosswalk is defined as . HAMILTON TRAFFIC AND SIDEWALKS ORDINANCE 1988 AMENDMENT ORDINANCE 2002.However, many pedestrians,including pedestrians with low vision,benefit from clearly marked crosswalks. For this reason, proposed Section 1. Most State DOTs follow the Manual of Uniform Traffic Control Devices (MUTCD) guidelines for marking crosswalks. Although the MUTCD does permit some variations for additional visibility, the basic specifications call for solid white lines not less than 1. US DOT, 1. 98. 8) (Figure 4- 4.
A study by Knoblauch, Testin, Smith, and Pietrucha (1. Figure 4- 4. 2, to be the most visible type of crosswalk marking for drivers. Diagonal striping can also enhance the visibility of a pedestrian crossing (Figure 4- 4. When a diagonal curb ramp is used at an intersection, a 1. In some situations, marked crosswalks might not be enough to ensure pedestrian safety. For example, at high- speed intersections without traffic signals, drivers often cannot perceive a marked crosswalk quickly enough to react to pedestrians in the roadway. This problem is compounded by the fact that . Some agencies around the United States consider that removing crosswalk markings improves pedestrian safety. Alternative treatments such as electronically activated crosswalks,pedestrian- actuated traffic controls,flashing traffic signals, light guard flashing crosswalks, traffic calming measures, raised crosswalks, and traffic signals are also being used. FHWA studies are currently being conducted to determine if these measures provide safer crossing for pedestrians. Most marked crosswalks observed during the sidewalk assessments were marked with paint. Others were built with contrasting materials such as red brick inside the crosswalk, bordered with gray concrete. Contrasting textures can provide tactile guidance for people with visual impairments, as well as visible colorized warnings. People's walking pace and starting pace varies depending on their personal situation. Older pedestrians might require longer starting times to verify that cars have stopped. They also might have slower reaction times and slower walking speeds. Powered wheelchair users and manual wheelchair users on level or downhill slopes might travel faster than other pedestrians. But on uphill slopes,manual wheelchair users might have slower travel speeds. At intersections without audible pedestrian signals,people with visual impairments generally require longer starting times because they rely on the sound of traffic for signal- timing information. The AASHTO Green Book indicates that . However, research on pedestrian walking speeds has demonstrated that more than 6. Kell and Fullerton, 1. The AASHTO Green Book recommends a walking rate of 1. It shall be unlawful to construct, reconstruct or repair any sidewalk within the city until the plans first have been. AASHTO, 1. 99. 5). Pedestrians of all mobility levels need to cross intersections. However, when crossing times accommodate only people who walk at or above the average walking speed, intersections become unusable for people who walk at a slower pace. To accommodate the slower walking speeds of some pedestrians, transportation agencies should consider extending their pedestrian signal cycles. Signal timing should be determined on a case- by- case basis, although extended signal cycles are strongly recommended at busy intersections that are unusually long or difficult to negotiate. Pedestrian- actuated traffic controls require the user to push a button to activate a walk signal. According to the MUTCD, pedestrian- actuated traffic controls should be installed when a traffic signal is installed under the Pedestrian Volume or School Crossing warrant, when an exclusive pedestrian phase is provided, when vehicular indications are not visible to pedestrians,and at any established school crossings with a signalized intersection (US DOT,1. If the intersection has a median,a button should be added to the median and both corners. Unfortunately, pedestrian- actuated control signals are often inaccessible to people with mobility impairments and people with visual impairments. To be accessible to wheelchair users and people with limited mobility, pedestrianactuated traffic controls need to be located as close as possible to the curb ramp without reducing the width of the path. They also need to be mounted low enough to permit people in wheelchairs to reach the buttons. ADAAG does not specify a height for pedestrian- actuated control systems. However, ADAAG Section 4. ADAAG, U. S. Access Board,1. The size and type of the button also affect the accessibility of the control. Larger raised buttons are easier for people with visual impairments to identify (Figure 4- 4. According to proposed Section 1. U. S. Access Board, 1. Pedestrian- actuated control buttons require more force to operate than most indoor buttons. However, people with limited hand strength or dexterity might be able to exert only a limited amount of force. To address this need, proposed Section 1. N (5 lbf) (U. S. Access Board,1. People with visual impairments might be at a disadvantage at intersections with pedestrian- actuated crossing controls if they are unaware that they need to use a control to initiate a pedestrian crossing signal. At an intersection with a pedestrian- actuated control button, a person with a visual impairment must detect whether a signal button is present,then push it and return to the curb to align for the crossing. This process might require several signal cycles if the button is not located within easy reach of the curb edge.
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