Improvements Worth Investigating

Across the U.S., roundabouts are being designed and installed at a rapid pace. It is becoming increasingly clear that current roundabout design practices do not yield the same access to crossing information for blind and low vision pedestrians as for sighted pedestrians. An accessible roundabout will provide nonvisual information about crosswalk and splitter island location, crossing direction, and safe crossing opportunities.

An understanding of the auditory, tactile, and other cues used by blind individuals as they negotiate intersections will aid engineers and planners in designing and building accessible roundabouts. Orientation and mobility (O&M) specialists can aid transportation professionals in understanding the demands of non-visual travel and the strategies that blind people use to successfully meet these demands. Much research and development work is needed to improve the usability of modern roundabouts by persons with blindness and visual impairments. It is essential that transportation engineers and planners involve themselves in this R&D by working to devise, implement and test design features with potential for improving accessibility. Promising avenues for further investigation fall into four broad task categories:

1. LOCATING THE CROSSWALK AND ESTABLISHING ALIGNMENT Landscaping, planters, pedestrian channelization, bollard-and-chain separation, railings, and other architectural features can delineate paths that lead to the crosswalk and prevent or discourage crossing at locations other than the crosswalk (see Figure 4 above). 

A distinctive edge, particularly paving-to-grass or a raised curb can provide orientation to the crossing direction. 

High-contrast markings and pedestrian routes that are well-lit at night will be useful to pedestrians who use residual vision to travel, the larger proportion of pedestrians who have vision impairments.  Lighting will also enhance pedestrian visibility to drivers.

A standardized tactile paving is used in many foreign countries to mark the crossing location for pedestrians traveling along the sidewalk.  For clarity of message, it should be a linear pattern that is distinguishable from the truncated dome pattern required in detectable warnings at the street edge (see Figure 7). 

Figure 7. Australian use of bar tiles across sidewalk to indicate crossing location

Figure 7. Australian use of bar tiles across sidewalk to indicate crossing location

When alignment using traffic sounds is not possible, other sources of alignment information must be available. Curb ramps with returned edges aligned with crosswalk direction offer useful cues for establishing a line of travel. It is probably also the case that when curb ramp slope is sufficiently steep to be detected underfoot, additional information for alignment can be provided by aligning the slope of the ramp with the crosswalk. However, the usefulness of slope information for alignment is an unresolved research question, and it raises issues where non-standard crosswalk location (e.g., diagonal or apex ramps) may give misleading information that can result in crossings outside the legal or marked crosswalk.

2. DETECTING WHEN IT IS APPROPRIATE TO CROSS

Designing roundabouts that provide pedestrians with nonvisual information about the appropriate time to initiate a street crossing appears to be the greatest challenge facing transportation engineers at roundabouts.  Key issues include:

  • First, to cross streets safely at roundabouts, there must be gaps in traffic that are long enough to permit pedestrians to cross to the splitter island (or from the splitter to the destination curb). As the traffic volume increases, the number of 'crossable' gaps decreases. 
     
  • Second, pedestrians must distinguish 'crossable' gaps from those that are too short to cross. They must make crossing decisions quickly, before approaching vehicles are too close. Longer gaps are needed to cross multi-lane roads than roads with only one lane in each direction. 
     
  • Third, instead of accepting a gap in moving traffic, pedestrians will sometimes cross in front of vehicles that have stopped for them (effectively creating a gap).  When (if) vehicles stop, pedestrians who are blind must use their hearing to detect the presence of the stopped vehicle, and they must then decide whether it is safe to walk in front of the vehicle.

As noted earlier, the speed of vehicles influences the likelihood that drivers will stop for pedestrians. Traffic calming measures (e.g., pedestrian signage, flashing beacons, raised crosswalks, narrow lanes, neckdowns) should be considered to maintain low speeds at the crosswalk. 
 

It is more difficult – and dangerous – to cross in front of stopped vehicles if the pedestrian is crossing more than one lane. Vehicles in the lane nearest the pedestrian stop but vehicles in other lanes (moving in the same direction) may not. To facilitate crossing in front of stopped vehicles, consideration should be given to locating crosswalks before the point where two-lane roads are flared to accommodate multiple-lane entries and exits.

Research is currently underway to determine the likelihood that vehicles will yield to pedestrians traveling with dog guides and long canes. Preliminary results about driver yielding behavior collected at 3 crosswalks suggest that most drivers do not yield to blind pedestrians waiting at a crosswalk.   This is particularly a problem at exit lanes. 

When vehicles do stop, they are sometimes not detected. This is typically the case when vehicles stop several car lengths away from the pedestrian, when the vehicle is relatively quiet (e.g., hybrid gas/electric vehicles), and/or when the sounds of other vehicles mask the sounds of the yielding vehicle. However, the strategy of crossing in front of a stopped vehicle should work where some vehicles stop and are detectable.

Some designers have incorporated stop bars and LED in-roadway warning lights (MUTCD, Chapter 4L) to encourage vehicles to yield to pedestrians at crosswalks.  The use of 'YIELD TO PEDESTRIAN'  signage at yield lines may also be effective.   Recommendations from a roundabouts summit sponsored by ITE and FHWA in December 2002 included raised crossings, particularly on exit legs to discourage driver acceleration.  Testing of the effectiveness of 'rumble strips' or similar sound-generating pavings before entry and exit has also been proposed.  Research is needed to determine if pedestrians can gain useful information on approaching and yielding vehicles from such cues.                   

Jurisdictions are also experimenting with ‘smart’ intersections that can sense and signal pedestrian presence. In situations where there are few 'crossable' gaps and where vehicles do not stop for pedestrians waiting to cross (or, because of multiple lanes, it is unsafe to cross in front of a stopped vehicle), specially-designed pedestrian signals -- models include 'HAWK' and 'TOUCAN' schemes that blink in amber unless activated.  Pre-emption signals utilized for emergency vehicles and trains may also have some application to provide street-crossing opportunities for pedestrians who are blind.  Research is needed to determine how to optimize such signalization for both pedestrians and drivers. Continuing advocacy for signalization can be expected until effective alternatives are developed.  Roundabouts with multiple lane entrances and exits, where signalization is more necessary to provide crossable (and detectable) gaps for pedestrians, would experience greater delays from signalization.

3. REMAINING IN THE CROSSWALK

Several design approaches may be used to provide directional information in the crossing.  Jurisdictions have experimented with ultra-high contrast markings and crosswalk lighting (useful for pedestrians who have low vision); raised crosswalks to provide a boundary, and providing a raised guidestrip at the centerline of the crosswalk.  By using the constant-contact cane technique, a blind pedestrian can identify and use tactile surface cues that provide information about the direction of the crosswalk. 

4. DETECTING THE DESTINATION SIDEWALK OR SPLITTER ISLAND

Detectable warnings at splitter islands and destination curb ramps signal one’s arrival at a pedestrian refuge. Splitter islands should be demarcated with detectable warnings at each street/sidewalk edge, separated by a width of untextured sidewalk surface.  Because detectable warnings mark the beginning and/or end of a safe pedestrian area,  they should be applied in pairs, separated by standard sidewalk surfacing.  Research indicates that 24 inches of detectable warning surface is needed for underfoot detection while walking. 

The use of similar design features across roundabouts will enhance their accessibility to persons who are blind.  Consistency in the location of crosswalks, in the design of splitter islands, in the use of bollards and pedestrian channelizing devices, separators, and edging, and in the use of landscaping features can provide effective non-visual cues for negotiating roundabouts.

When a roundabout is introduced to a community through newspaper and TV stories, be sure to emphasize that pedestrians are expected to cross there. Show photos and film of drivers yielding to pedestrians.

Improvements for gap creation

  • pedestrian-actuated crossing signals (HAWK, puffin, or similar)
  • upstream /downleg signals 
  • signal metering (as at freeway ramps)
  • pre-emption