Dwight Kingsbury, Ph.D.
October 28, 2002
Comment on Draft Guidelines for Accessible Public Rights-of-Way, published in
the Federal Register, 17 June 2002.
As a pedestrian safety analyst, I support the goals of this effort, but share
the concerns expressed by others (e.g., AASHTO) that in some sections, the draft
guidelines propose inflexible, "Gordian knot" criteria to the application of
pedestrian crossing features that are more appropriately and effectively
evaluated through the application of engineering judgment, in the light of the
"Manual on Uniform Traffic Control Devices" and other engineering guidance
Specifically, I am concerned about the following.
S. 1105.3 would require calculation of pedestrian signal phase timing using a
pedestrian walking speed of 3.0 ft per second. Use of such a speed is certainly
appropriate in some locations, as recognized by the MUTCD, but blanket
application would cause unnecessary delays at many crossings. Delays that are
not perceived to be justified may increase the reluctance of drivers to yield to
pedestrians in crosswalks.
S. 1105.5.3 would require installation of elevators where the rise of a ramped
approach exceeds 60 inches. This would be quite expensive and the elevators
would require careful monitoring and maintenance. Many people have security
concerns about using outdoor elevators. Adoption of this requirement would
likely limit installation of new pedestrian facilities at locations where they
are not currently present. Guidelines for use of elevators can and should be
described in best practices documents.
S. 1105.6.2 would require provision of a pedestrian activated signal at each
segment of a roundabout crosswalk. Although pedestrians often expect they will
have difficulty using such crosswalks, prior to construction, I have never heard
of any pedestrian request for a signal at a signal-lane roundabout, after it has
opened. Adoption of this requirement could result in a reduction of the use of
marked crosswalks at roundabouts. I concur with AASHTO that this section should
be reserved, pending completion of NCHRP Project 3-65, "Applying Roundabouts in
the United States."
S. 1105.7 would required provision of a pedestrian activated signal where
crosswalks are provided at right or left turn slip lanes. The problem is that,
if the slip lane is designed to facilitate a high speed turn, and the signal is
used infrequently, it will be ineffective; many drivers simply fail to heed
signal indications they are not used to seeing. The failure of drivers to yield
to pedestrians in slip lane crosswalks is better addressed through design, e.g.,
greater use of high-entry-angle slip lanes such as those used in Australia (cf.
the Austroads "Guide to Traffic Engineering Practice," Part 5). Let us hope that
NCHRP Project 3-72, "Lane Widths, Channelized Right Turns, and Right Turn
Deceleration Lanes in Urban and Suburban Areas," will produce some useful
recommendations for the pedestrian crossing problem at slip lanes.
S. 1106 would require all pedestrian signal systems to use audible and
vibrotactile indications. In Florida, there have been differences among visually
impaired pedestrians as to the usefulness of audible signal systems. Some blind
persons believe these features are unnecessary, or create a false sense of
security, or make it difficult to hear traffic (at least, if not installed
properly). They must also be maintained. It is probably better to continue with
the current practice of considering installation of such systems on request.
I also concur with AASHTO that the hard conversion of dimensions stated in US
customary units into their SI equivalents lends itself to impractical inferences
with respect to tolerances. Metric tolerances need to be clarified.
Dwight Kingsbury, Ph.D.