Crosswalk Worksheet Variables
Figure D-2. Diagram A demonstrates the crosswalk width measurement of a standard crosswalk. Diagram B demonstrates crosswalk width measurement of a crosswalk at a channelized right turn lane.
Crosswalk width is defined as the curb-to-curb measurement taken at the midpoint of the crosswalk. A longer crosswalk increases the potential that pedestrians who are blind will veer out of the crosswalk, as well as making it more critical for the blind pedestrian to start as quickly as possible after the onset of the WALK interval. In the case of a channelized right turn island, the crosswalk length should be measured from curb to island (Figure D-2). Widths less than 40 ft receive no points.
Speed Limit (street being crossed)
The higher the speed of the vehicles on the street being crossed, the lower the probability of avoiding an incident should a visually impaired pedestrian mistakenly step into the street and the higher the probability of injury should a crash occur. Since operating speeds are not always available, the posted speed limit can be used as a surrogate measure. Speed limits of 20 mph and lower receive no points.
There are several geometric factors at a crosswalk that can negatively impact upon the ability of a blind pedestrian to safely cross the street. Each of the factors on the form under this heading is defined below.
Curb radius > 25 ft (either corner)
It is more difficult to establish an initial correct heading where curb radii are wide. Incorrect headings can result in pedestrians who are blind walking toward the center of the intersection.
Islands or medians
Raised or painted crossing islands and medians can confuse blind pedestrians during their crossing, slow or delay their crossing, affect crossing alignment, and generally make the crossing more difficult. Points should be added for any median or island, painted, raised, or cut-through, that crosses the crosswalk, particularly when the crosswalk changes direction at the island. Islands that are present for channelized right turns are taken into account in the "Channelized right turn island" factor.
Transverse slope on crosswalk (cross slope)
Crosswalks with a severe cross slope (> 5 %) can lead to veering toward the downhill side by a blind pedestrian during the crossing. Depending on the direction of the cross slope, they could either veer into the intersection or into the approach leg. A beaconing APS may counter this tendency to veer.
Apex (diagonal) curb ramp (either corner)
Where the slope of the curb ramp is not aligned with the direction of travel on the crosswalk, blind pedestrians may misalign for the crossing and walk into the flow of parallel traffic. This misalignment most commonly occurs with "apex" curb ramp configurations (Figure D-3). This apex configuration occurs when the corner only has one ramp that points toward the center of the intersection, usually for the purpose of serving two perpendicular crosswalks. If the corner has two ramps that each serves one crosswalk, the corner has a perpendicular ramp configuration (Figure D-4).
Figure D-3a. Photo of an apex ramp configuration
Figure D-3b. Sketch of an apex ramp configuration
Figure D-4a. Photo of a perpendicular ramp configuration
Figure D-4b. Sketch of a perpendicular ramp configuration
Channelized right-turn lane island
Crossings at a channelized right-turn lane normally require the pedestrian to cross to the island in one direction, reorient themselves, and then complete the crossing in a different direction (see Figure D-5). This direction change is potentially confusing to blind pedestrians. Most of the right-turn lanes where such islands are present are unsignalized. Therefore, an APS will not be installed for the right-turn lane crossing unless a traffic signal is being added. The APS installation that should be considered at these locations is on island for the crosswalks that cross the through travel lanes. The locator tones, as well as the WALK interval tones and speech messages, on an APS device under these conditions may assist the visually-impaired pedestrian with the reorientation that is required to find the correct crosswalk.
Note: Islands and medians separating traffic lanes in the middle of the road are taken into account by the "Islands or medians" variable. If the right-turn lane is signalized, refer to the "Channelized right turn lane under signal control" variable.
Figure D-6. Crosswalk A is defined as skewed because a pedestrian following the sidewalk line is headed toward the parallel traffic Crosswalk B is not skewed because a pedestrian following the sidewalk line is headed toward the opposite corner.
Figure D-7. This crosswalk is defined as skewed because it is timed for median crossing (two-stage) and a blind pedestrian might miss the median due to the bent crosswalk.
If the direction of travel on a crosswalk is different from the direction of travel on the approaching sidewalk (is skewed), the consequence of failure to establish a heading toward the opposite corner is often that blind pedestrians will walk toward the center of the intersection and into the path of parallel traffic.
The degree of skew can vary from crosswalk to crosswalk. Skew, in this case, is not defined by the angle at which the streets intersect. If a blind pedestrian walking a straight line from the approaching sidewalk is headed toward parallel traffic lanes, the crosswalk is skewed (see crosswalk A in Figure D-6). If the blind pedestrian would end up deviating from the crosswalk but would still arrive at the opposite corner, the crosswalk is not defined as skewed for this rating tool (see crosswalk B in Figure D-6).
Skewing can also occur at crosswalks where the pedestrian walk signal only gives enough time for the pedestrian to reach a median. In this case, the blind pedestrian must be able to find the median to wait for the next signal cycle. A skewed or bent crosswalk may cause the pedestrian to miss the median. In this situation, the crosswalk is defined as skewed (Figure D-7).
Determination of skew should not consider the island of a channelized right turn (Figure D-5). Although crossing from curb to curb may involve a crooked path due to a direction change at the island, this disadvantage is already accounted for in the fields relating to channelized turn islands.
Pedestrian Signal Control
The ability of a pedestrian who is visually impaired to safely cross at a crosswalk can be impacted by the WALK interval timing and other pedestrian signal control features. Each of these factors is defined below.
Push button actuation required for WALK
At unfamiliar intersections, pedestrians who are blind have no way to know pedestrian actuation is required unless there is an APS with a locator tone. Therefore pedestrians who are blind are unlikely to use pushbuttons at unfamiliar intersections and are more likely to cross relying only on the cue of traffic surge, whether or not it corresponds to the onset of the walk interval. Even if the parallel traffic surge is interpreted correctly, the green phase timing may not be sufficient to allow a pedestrian to safely cross the street. The problem is compounded when the pushbutton is not right beside the probable location of a pedestrian who is waiting to cross; this may require pedestrians who are blind or visually impaired to repeatedly leave their chosen starting location and heading and push the button again, and then return to their chosen starting location and re-establish their heading.
Non-concurrent WALK interval
Some signal timing plans at multi-leg intersections display the pedestrian WALK signal at a different time than the green phase for adjacent parallel traffic (Figure D-8). Pedestrians who are blind or visually impaired will typically assume that the WALK interval will begin with the onset of through traffic on the parallel street. Without an APS, they will not know the appropriate time to cross at such locations.
Leading Pedestrian Interval — LPI (with parallel street green)
The LPI permits pedestrians parallel to a traffic stream to move prior to the vehicles receiving a green signal, with a goal of allowing pedestrians to "claim" the crosswalk space prior to vehicles that may be turning right (Figure D-9). Unfortunately, this treatment creates a scenario in which blind pedestrians are unable to detect the beginning of the walk interval if there is no audible indication. Subsequently, they may begin crossing only when the parallel traffic starts, which may be too late in the pedestrian phase and at a time when drivers are not expecting them.
Timed for crossing to median island
On wide streets with medians or crossing islands, blind pedestrians cannot easily determine whether the WALK signal is intended to allow them to cross the entire street or only to the mid-point. Without an APS providing an audible cue at the median, blind pedestrians are unable to recognize that they must stop there, which may place them in a high-risk situation. The MUTCD states: "Where the pedestrian clearance time is sufficient only for crossing from the curb or shoulder to a median of sufficient width for pedestrians to wait, additional measures should be considered, such as median-mounted pedestrian signals or additional signing." (MUTCD 2003)
Vehicle Signal Control
The types of signal phases available for vehicle traffic can greatly impact upon the ability of the pedestrian who is visually impaired to understand the audible cues from the traffic surges of various movements and make correct decisions about when it is appropriate to cross the street. Each type of signal phasing that may lead to this ambiguity is defined below.
Right-Turn-On-Red (RTOR) permitted (on parallel street)
The allowance of RTOR on the parallel street may create a false audible cue for the blind pedestrian (Figure D-10). Vehicles turning right after stopping may be interpreted as indicating the onset of the parallel green phase, and pedestrians who are blind or visually impaired may begin to cross the street at the wrong time. RTOR vehicles also make it harder to audibly recognize the onset of the parallel traffic movement.
The allowance of RTOR during an exclusive pedestrian phase also sends mixed signals. If vehicles are turning, blind pedestrians may not be aware that they have a WALK interval. If they do recognize it, there may be a delayed initiation of crossing which means they may not begin crossing on the WALK interval and may still be in the street during the DONT WALK interval.
Leading protected left-turn phase (on parallel street)
It can be difficult for a blind pedestrian to audibly distinguish between the surge of traffic at the beginning of a protected left-turn phase and the beginning of the through traffic phase (Figure D-11). The moving cars of the leading left-turn phase may also mask the sounds of the parallel through traffic beginning to move, particularly if the protected left-turn interval is followed by a permissive left-turn interval.
Note: Points are not given for lagging left-turn phases, which are much better for a blind pedestrian. With a lagging left-turn interval, the through traffic on the parallel street is the first vehicular maneuver after traffic stops on the cross street. The onset of the WALK interval usually occurs at the same time and allows all pedestrians, including blind pedestrians to initiate the crossing. The pedestrians are then typically clear of the intersection by the time the lagging left-turn interval begins.
Protected right-turn-only phase (on parallel street)
The surge of traffic by right-turning vehicles using a protected right-turn phase may be incorrectly interpreted as the beginning of the parallel through traffic surge and the simultaneous onset of the WALK interval (Figure D-12).
Channelized right-turn lane under signal control
Turning vehicles at channelized turns are typically under yield control. They must stop only if there is traffic approaching intersection the cross street, or if a pedestrian is in the crosswalk. However, at some channelized right-turn lanes, vehicles are controlled by a signal that prohibits turns if the signal is red (Figure D-13). Without an audible indication, a blind pedestrian will not know that traffic at the channelized turn lane is under signal control and may attempt to cross when the traffic has a green signal. This confusion of priorities may lead to an unsafe crossing.
Note: The point values for this factor are for the "signalization" component only. A channelized right-turn lane that is signalized will also receive points under "Channelized right turn island".
Off-Peak Traffic Presence
Traffic volume may impede or assist visually impaired pedestrians. Traffic flow that is very light or erratic (which most often occurs in off-peak periods) makes it difficult to use traffic sound to recognize signal changes. In such cases, audible signals can help to determine the onset of the walk interval. While many municipalities may have turning movement counts or average daily traffic counts, it is not a simple or uniform process to translate these numbers into a meaningful measure for assessing off-peak traffic presence. Instead, this variable is scored on the basis of the proportion of time that at least two vehicles are present at the beginning of a green phase in through lanes that are parallel to the path of the pedestrian.
Figure D-14. Crosswalks A and B, across top of the T, at a T-intersection, have no parallel through traffic. In contrast, Crosswalk C has parallel through traffic.
Note that traffic presence in this category refers to traffic that is parallel to the crosswalk and passes straight through the intersection. If there is no through traffic at the intersection (no lanes continuing straight), there is no reliable traffic available for the blind pedestrian to use as a cue that the walk interval has begun, and the crosswalk would get a rating of "None" and receive the maximum number of points. An example of such a configuration is a T-intersection (Figure D-14).
Noting the number of signal cycles with 2 or more through vehicles over 5 to 10 cycles during the off-peak should be sufficient for determining the percentage for scoring this variable. The levels provided on the worksheet reflect the results that may be acquired in such an exercise.
Distance to Alternative APS Crossing
If there is another signalized crosswalk with APS in close proximity to the intersection being rated, the intersection should receive a lower score (lower priority for APS) than a similar intersection where there is no nearby crossing alternative.
If an alternative accessible crossing is present and scored as such, care must be taken to ensure that the alternative crossing meets the need of the blind traveler by getting them to/from the destination. Just because a crossing is close, it may not always be in a location that helps get the person to their destination. A local Orientation & Mobility Specialist or a pedestrian who has requested an APS can assist with making this determination.
Pedestrian Pushbutton Location (either corner)
Section 4E.09 of the MUTCD provides guidance on where pedestrian pushbuttons with APS should be located as follows:
- Adjacent to a level all-weather surface to provide access from a wheelchair, and where there is an all-weather surface, wheelchair accessible route to the ramp;
- Within 1.5 m (5 ft) of the crosswalk extended;
- Within 3 m (10 ft) of the edge of the curb, shoulder, or pavement; and
- Parallel to the crosswalk to be used. (MUTCD 2003)
The Crosswalk Worksheet provides for points to be added if the location of pedestrian push buttons on either side of a crosswalk does not meet either B or C above. In essence, this variable will give an intersection with poorly located pushbuttons a higher priority for the installation of APS over an intersection with properly located pushbuttons (assuming all other characteristics of the two intersections are the same). Poorly located pushbuttons create much greater difficulty for blind pedestrians in terms of being easily accessible, being positioned in a manner to provide alignment cues, and being located close enough to the curb to be pushed and then cross on the same cycle.
Requests for APS
Requests for an APS may come from a pedestrian who is visually impaired or from an Orientation and Mobility professional. These requests are usually very specific " the individual needs to travel from their home to their workplace and needs to cross this street using this crosswalk. Such requests should increase the priority for APS.
[ back to top ]