Posted on April 18, 2011 5:13 PM
NCHRP study on crossing solutions at roundabouts and channelized turn lanes for pedestrians with vision disabilities
A new report (NCHRP Report 674) explores the issues and design solutions for the accessibility of two complex intersection forms for blind pedestrians: intersections with channelized right turn lanes (CTLs) and modern roundabouts with one-lane and two-lane approaches. The report offers guidance and information related to the establishment of safe crossings for blind pedestrians at these intersections.
For CTLs, the study team concludes that channelized turn lane locations can be very challenging to cross for blind pedestrians and signalized treatments may need to be considered at these sites. Since field tests indicated that high vehicle speeds contributed to the high incidence of unsafe crossings at CTL locations, geometric designs and treatments intended to reduce vehicular speed -- such as traffic calming designs, raised crosswalks, pork-chop islands, narrow lane width, small curve radii, and the absence of an acceleration lane -- may further decrease the likelihood of unsafe crossing for pedestrians who are blind.
For single-lane roundabouts, the study concludes that while some blind research participants had difficulties crossing single-lane roundabouts in a safe manner, these sites appear not to pose crossing difficulties that are beyond those experienced by many blind travelers at similar signalized intersections. Key factors for safety here include:
- Low vehicle speeds at the crosswalk
- The willingness of a majority of drivers to yield to pedestrians
- Properly installed detectable warning surfaces at all transition points
- Availability of certified orientation and mobility instruction customized to roundabout crossings
The study also confirmed that two-lane roundabouts are challenging and not accessible without the provision of additional crossing treatments or a drastic change toward an increase in likelihood of drivers voluntarily yielding to pedestrians.