James D. Perkins, P.E.
|October 28, 2002|
James D. Perkins, P.E.
I have the following observations and comments on the Draft Guidelines for Accessible Public ROW (June 17, 2002).
1102.4 The guidelines state "Where sidewalks are provided, they shall contain a continuous pedestrian access route complying with 1103." This states that all sidewalks shall be accessible. What is the reasoning for including 1102.10 (stairs), since stairs are an inaccessible item for people in wheelchairs?
1220.127.116.11 For areas with reduced vertical clearance the draft
guidelines state that "The leading edge of such guardrail or barrier shall be located 27 inches (685 mm) maximum above the finish floor or ground." With the maximum height set at 27" with no minimum height it is conceivable to create a hazardous obstruction or tripping hazard. A section for standard ADA barriers is needed in the draft guidelines.
118.104.22.168 The draft guidelines state that "...drop-offs at diverging
segments shall be protected with a barrier." No definition of a barrier is given. A section for standard ADA barriers is needed in the draft guidelines.
1104.3.7 What is the need for a clear space beyond the curb line?
This has greater impacts than will probably first be realized. It adds to pedestrian signal times and adds complexity to drainage and roadway layouts.
122.214.171.124 The draft guidelines state that for roundabouts "Continuous barriers shall be provided along the street side of the sidewalk where pedestrian crossing is prohibited." No information on the barrier is given with the exception of the bottom rail. A section for standard ADA barriers is needed in the draft guidelines. What is the extent of the needed barriers? Are they required even at curbside sidewalks?
1105.6.2 The requirement for pedestrian activated traffic signals at splitter islands is inconsistent with the exception in 1106.2.1.
1105.7 Currently many sliplanes are installed at unsignalized
intersections. Requiring all slip lanes to be signalized will effectively negate their use on many intersections and thus increase traffic congestion and construction cost. If a jurisdiction decides on the need for an added turnlane according to the guide they will either install a signalized slip lane or add another lane of traffic and still create an unsignalized intersection. If an unsignalized intersection is chosen the net result is added cost for no gain from installing an unsignalized slip lane would provide the same net affect for pedestrians. This section also requires a pedestrian activated signal at all splitter islands. This is not consistent with the exception in section 1106.2.1.
1108.1.3 I am deeply concerned about detectable warnings having a
visual contrast of dark-on-light. A person with little visual acuity will perceive a dark area as a hole or pit and thus avoid the dark area or accept that a dark area is a detectable warning area and end up walking into a pit (i.e. an open utility vault). Allowing dark-on-light is only setting up the public for some dangerous situations.
The following comments all have a common theme- that is many of our streets and roadways have slopes and grades to them.
In 1103.5 the pedestrian access route can follow the road grade on a steeply sloped street. How does this mesh with 1105.5.3 where elevators or lifts are required at underpasses and overpasses when the rise is greater than 60"? The reason given for the elevator or lift requirement is that lengthy ramps often are unusable due to the exertion required in maneuvering wheelchairs upslope. Following this logic all sidewalks (following the roadgrade) with slopes greater than 1:12 (8%) would require elevators and lifts- clearly infeasible. It seems reasonable to propose that many of the requirements of the proposed rules (i.e. 1103.4 etc.) should be eased in areas of steep terrain.
1103.5 This cannot be consistently met in sloping terrain where 1126.96.36.199
is met. If the sidewalk is at a running grade greater than 1:12 then either the upside walk or downside walk will have to be steeper than 1:12 or steeper than the running slope of the road in order to meet the top landing of the ramp.
1104.2.2 This cannot be met in sloping terrain where 1188.8.131.52 is met. See 1103.5 above for reasoning.
1104.2.3 This cannot be met in sloping terrain where 1184.108.40.206 is met. See 1103.5 above for reasoning.
1105.2.2 Requiring a maximum 2% cross slope on crosswalks is often infeasible
in sloping terrain. As an example assume a crossing street with a rather benign
5% grade and the intersection sloped at 5%. Requiring crosswalks to have a
maximum 2% cross slope would require the whole intersection to achieve a 2%
slope (due to restrictions on vertical curves). With a roadway width of 50' (3
lanes with bike lanes) and 30' curb radii the distance outside to outside of the
crosswalks will be about 93' apart and the grade difference between the constant
5% grade and the 2% intersection grade would be about 1 ½'. This would require
either ROW acquisition or retaining wall to contain the grade difference. The
effect of the 2% cross slope would also extend for hundreds of feet from the
intersection due to the required vertical curve limits imposed by national road
Thank you for the opportunity to comment.
index previous comment next comment