Crossing Enhancements
This section describes several methods that can be used to improve the safety of pedestrians at crossings, including:
Advance Stop Lines/Advance Yield Markings
Placing a vehicle stop or yield line back from the crosswalk has benefits at both signalized intersections and midblock crossings.
At signalized intersections, placing an advance stop/yield line 1.2 m (4 ft) from the crosswalk allows pedestrians and drivers to have a clearer view of each other and more time in which to assess each other's intentions.
At midblock marked crosswalks, an advance stop/yield line can help prevent a major crash type at crosswalks on multilane roads: the multiple threat crash. This occurs when a driver stops to let a pedestrian cross, but too close to the crosswalk, masking visibility of the adjacent travel lane. A motorist proceeding in the adjacent lane doesn't notice the first car has stopped to let a pedestrian cross. The pedestrian continues to cross, doesn't see the other car coming, which can result in a high-speed crash. High speed crashes usually result in fatalities or very severe injuries.
An advance stop/yield line placed 6 to 15 m (20 to 50 ft) ahead of the crosswalk can greatly reduce the likelihood of a multiple-threat crash, as this encourages drivers to stop back far enough so a pedestrian can see if a second motor vehicle is not stopping and be able to take evasive action. Ten meters (30 ft) has been found to be a good distance for most purposes.
The advance yield/stop line should be supplemented with "Stop Here For Pedestrians" signs (R1-5 or R1-5a) to alert drivers where to stop to let a pedestrian cross.
One study found that use of a "sign alone reduced conflicts between drivers and pedestrians by 67 percent. With the addition of an advanced stop/yield line, this type of conflict was reduced by 90 percent compared to baseline levels.
The decision to use an advance stop or yield line depends on state law. Most states require drivers to yield to pedestrians; about a dozen states require drivers to stop for pedestrians.
Purpose
- Improve visibility of pedestrians to motorists
- Allow pedestrians to advance in a crosswalk before motor vehicles turn
- Prevent multiple-threat crashes
Considerations
- Effectiveness depends on motorist compliance with the marked stop line.
- If placed too far in advance of the crosswalk, motorists may ignore the line.
Estimated cost
There is little additional cost when the advance stop/yield line is installed on new paving or as part of repaving projects.
Curb Extensions
Curb extensions—also known as bulb-outs or neckdowns—extend the sidewalk or curb line out into the parking lane, which reduces the effective street width. Curb extensions significantly improve pedestrian crossings by reducing the pedestrian crossing distance, visually and physically narrowing the roadway, improving the ability of pedestrians and motorists to see each other, and reducing the time that pedestrians are in the street.
Curb extensions placed at an intersection essentially prevent motorists from parking in or too close to a crosswalk or from blocking a curb ramp or crosswalk. Motor vehicles parked too close to corners present a threat to pedestrian safety, since they block sightlines, obscure visibility of pedestrians and other vehicles, and make turning particularly difficult for emergency vehicles and trucks. Curb extensions also provide an excellent place to locate stop signs which will be more visible since they cannot be easily blocked by parked cars. Motorists are encouraged to travel more slowly at intersections or midblock locations with curb extensions, as the restricted street width sends a visual cue to motorists. Turning speeds at intersections can be reduced with curb extensions (curb radii should be as tight as is practicable). Curb extensions also provide additional space for curb ramps and for level sidewalks where existing space is limited.
Curb extensions are only appropriate where there is an on-street parking lane. Curb extensions must not extend into travel lanes, bicycle lanes, or shoulders (curb extensions should not extend more than 1.8 m (6 ft) from the curb). The turning needs of larger vehicles, such as school buses, need to be considered in curb extension design.
Purpose
- Improve safety for pedestrians and motorists at intersections.
- Increase visibility and reduce speed of turning vehicles.
- Encourage pedestrians to cross at designated locations.
- Prevent motor vehicles from parking at corners.
- Shorten crossing distance and reduce pedestrian exposure.
Considerations
- Curb extensions can provide adequate space on narrow sidewalks for curb ramps and landings.
- Curb extensions should only be used where there is a parking lane, and where transit and bicyclists would be traveling outside the curb edge for the length of the street.
- Midblock extensions provide an opportunity to enhance midblock crossings. Care should be taken to ensure that street furniture and landscaping do not block motorists' views of pedestrians.
- Where intersections are used by significant numbers of trucks or buses, the curb extensions need to be designed to accommodate them. However, it is important to take into consideration that those vehicles should not be going at high speeds, and most can make a tight turn at slow speeds. In some situations, curb bulbs can actually make it easier for trucks to turn by bringing them out, away from the curb, thereby giving them a better angle to enter the receiving lane.
- It is not necessary for a roadway to be designed so that a vehicle can turn from a curb lane to a curb lane. Vehicles can often encroach into adjacent lanes safely where volumes are low and/or speeds are slow. Speeds should be slower in a pedestrian environment.
- Emergency access is often improved through the use of curb extensions if intersections are kept clear of parked cars. Fire engines and other emergency vehicles can climb a curb where they would not be able to move a parked car. At midblock locations, curb extensions can keep fire hydrants clear of parked cars and make them more accessible.
- Curb extensions can create additional space for curb ramps, landscaping, and street furniture that are sensitive to motorist and pedestrian sightlines; this is especially beneficial where sidewalks are otherwise too narrow.
- Ensure that curb extension design facilitates adequate drainage.
Estimated cost
Curb extensions cost from $5,000 to $25,000 per corner, depending on design and site conditions. Drainage is usually the most significant determinant of cost. If the curb extension area is large and special pavement and street furnishings and planting are included, costs would also be higher. Costs can go up significantly if something major, such as a utility pole or controller box, is moved.
Crossing Islands
Crossing islands—also known as center islands, refuge islands, pedestrian islands, or median slow points—are raised islands placed in the center of the street at intersections or midblock to help protect crossing pedestrians from motor vehicles. Center crossing islands allow pedestrians to deal with only one direction of traffic at a time, and they enable them to stop partway across the street and wait for an adequate gap in traffic before crossing the second half of the street. Where midblock or intersection crosswalks are installed at uncontrolled locations (i.e., where no traffic signals or stop signs exist), crossing islands should be considered as a supplement to the crosswalk. They are also appropriate at signalized crossings though they should never be used to create a two-phased pedestrian crossing at a signalized intersection (don't leave pedestrian stuck on a crossing island between moving lanes of traffic). Signalized, two-phased pedestrian crossings can be used at midblock locations where the crossing is designed with a "Z" pattern (pedestrian crosses to the middle with one signal, traverses down the fenced median at least 30 feet and then crosses to the other side with a second signal). If there is enough width, center crossing islands and curb extensions can be used together to create a highly improved pedestrian crossing. Detectable warnings are needed at cut-throughs to identify the pedestrian refuge area.
This kind of facility has been demonstrated to significantly decrease the percentage of pedestrian crashes. The factors contributing to pedestrian safety include reduced conflicts, reduced vehicle speeds approaching the island (the approach can be designed to force a greater slowing of cars, depending on how dramatic the curvature is), greater attention called to the existence of a pedestrian crossing, opportunities for additional signs in the middle of the road, and reduced exposure time for pedestrians.
Curb extensions may be built in conjunction with center crossing islands where there is on-street parking. Care should be taken to maintain bicycle access. Bicycle lanes (or shoulders, or whatever space is being used for bicycle travel) must not be eliminated or squeezed in order to create the curb extensions or islands.
Purpose
- Enhance pedestrian crossings, particularly at unsignalized crossing points
- Reduce vehicle speeds approaching pedestrian crossings
- Highlight pedestrian crossings
Considerations
- Do not squeeze bicycle access.
- Illuminate or highlight islands with street lights, signs, and/or reflectors to ensure that motorists see them.
- Design islands to accommodate pedestrians in wheelchairs. A cut-through design such as depicted in the photo must include detectable warnings.
- Crossing islands at intersections or near driveways may affect left-turn access.
Estimated cost
Costs range from $4,000 to $30,000. The cost for an asphalt island or one without landscaping is less than the cost of installing a raised concrete pedestrian island with landscaping.
