Charles Carmalt
|
October 28, 2002 |
In a separate e-mail I will be sending a Microsoft Word version of
these comments with formatting as an attachment, which you may find more
convenient to use. I will also mail that document as a letter to the Access
Board.
My original intent in responding to the draft standards was that I had been
informed that the Board would be establishing 60” as the minimum width for
sidewalks. I am glad to see that the Board has instead recommended a minimum
width of 48”. As discussed below, I believe that the wider width would result in
fewer sidewalks being constructed, and would be severely counter-productive.
However, the idea of requiring wider sidewalk widths is consistent with a
general fault of many of the proposed guidelines. The guidelines appear to have
been drafted to address common problems experienced in cities by different types
of persons having disabilities, or at intersections on very heavily traveled
arterial highways. However, the regulations of the Access Board will extend
throughout the nation and will be applied on streets, roads, highways, lanes and
other public rights-of-way in rural, exurban, suburban and neighborhood
environments, not just in city centers. In many of these environments, some of
the mandatory standards presented would be either inappropriate or, as in the
case of 5’ sidewalks, counter-productive by discouraging roadway design
practices that soften the roadway environment and make roadways more convenient
for all non-motorized users.
I encourage you to critically evaluate the effect and appropriateness of these
standards in environments where the frequency and intensity of conflicts between
different users can be anticipated to be substantially less than in city centers
and similar intensely used areas.
My comments are as follows:
Section 1101.3
Defined Terms
Cross slope. Cross-slope is not usually called superelevation. Superelevation is
a roadway design treatment that adjusts the cross slope to mitigate the impact
of curvature. I recommend that the second sentence be deleted.
Similarly, if you must define superelevation, you should define it using
language that in fact is descriptive. I looked for a definition in both AASHTO’s
Policy on Geometric Design and ITE’s Traffic Engineering Handbook but found
none. I suggest something like the following:
Superelevation – an adjustment to the cross slope of a traveled way that is
introduced to mitigate the outward centrifugal force created by a horizontal
curve. Superelevation is conventionally termed “banking”.
However, I question whether a definition is required. You may wish to conduct a
search to determine if it is used in the text of the regulations.
Note that if you do use the term, you should use an all-inclusive term such as
traveled way rather than roadway or highway. Superelevation can be introduced on
paths and sidewalks as well as highways. Conversely, reverse superelevation, or
banking in the reverse direction of a curve, can pose a special problem for
persons in wheelchairs. Unfortunately, it is relatively easy to inadvertently
introduce reverse superelevation along a pedestrian access route if the designer
is not attentive.
Section 1102.10
Stairs. This section should be amended to provide guidance regarding where the
use of stairs may be appropriate in public rights-of-ways. The guidance should
strongly discourage the use of stairs except in situations where the natural
grade clearly necessitates their use of stairs. Thoughtless designers who
introduce unnecessary stairs into public the right-of-way are being cruel to all
users.
When stairs are introduced, they should be located out of the preferred
pedestrian route so that most users will be attracted to a route without
barriers.
Section 1102.14
On-street parking. On-street parking requirements should only apply in locations
where the parking is used by the general public in a mixed use environment and
where the parking supply is constrained.
On most residential streets in suburbs, and many other streets, parking is
permitted but only lightly used. I feel certain that most persons that might
seek an accessible space in a confined and shared parking environment would seek
to use a parking space most convenient to the specific destination in an
unconfined environment. This could include blocking the driveway at the intended
destination.
In areas surrounding Lawrenceville, municipalities use accessible parking
regulations to regulate spaces in front of homes or businesses that have
individuals who regularly need such a reservation. This more flexible approach
helps to protect proximity of parking for persons who need such protection. At
locations where the general public is being encouraged to park, such as in a
village center, the approach proposed in the draft regulations is currently
followed.
This section should establish conditions under which it should be implemented.
This could either be a warrant based system using a variable associated with
constrained parking demand, or it could be based on engineering judgment. Note
that an approach frequently followed is to supply accessible spaces in
convenient segregated off-street locations and allow the on-street supply to be
used for persons not requiring accessible design. Where practical, this approach
usually results in superior design.
Proposed 1102.14 is an example of a regulation aimed at a dense urban
environment that would be impractical or counter-productive in other
environments. It should be more narrowly drafted.
Section 1103.3
Clear width.
I strongly endorse the use of 48 inches as the minimum clear width of the
pedestrian access route in most situations. At the same time, there clearly are
situations where higher pedestrian volumes, or the likely use of pedestrian
routes by persons in wheelchairs, will require a greater width.
Some language should be included to provide guidance where such additional width
is required – for example surrounding hospitals, in retail centers, near nursing
homes or other places that serve persons with disabilities, etc. A methodology
should be presented for determining the amount of additional width required and
the extent of the surrounding area within which widening should occur.
Section 1103.3
The minimum clear width should be enlarged to six feet if the pedestrian access
route immediately abuts a curb. (Note: a curb represents a vertical edge that is
a hazard not only for persons in wheel chairs and blind persons but for all
pedestrians. Slipping off of a curb can cause serious injury. A requirement that
sidewalks be widened if they abut a curb is relatively standard.
Section 1103
Add a section on edges.
This section should include specific guidance regarding the treatment of edges
adjacent to pedestrian access routes. Routes that abut a vertical surface such
as a wall should be widened by at least one foot.
The surface of a pedestrian access route should not directly abut an edge.
Language similar to 405.9.2 should be provided describing edges and design
approaches presented to indicated the protection that should be provided.
I recently was walking along a bridge over a river that was constructed within
the past three years. The wooden sidewalk has railings. However, the 5’ boards
that create the sidewalk terminate with no edge treatment or curb. Instead, a
vertical drop to the river is presented at the edge. The user of a wheelchair
could readily have a wheel caught in this edge, would be thrown against the
railing and would be unable to extricate himself or herself. I will be working
to correct this instance, put the regulations should prohibit it from occurring
along a pedestrian access route.
Section 1103.5
Grade Exception. The proposed regulations allow for the pedestrian access route
to be steeper than the grade of the adjacent roadway. I understand that there
may be unique conditions in which this may be appropriate, in particular to
create level platforms at doorways. However, the blanket exception, as worded,
goes to far.
In our area, and in many other suburban areas, designers of late have become
very fond of introducing unnecessary vertical and horizontal curvature into
sidewalks to make them more appealing to motorists. The vertical curves
especially are an unwarranted and unnecessary burden to all pedestrians, and are
a viciously cruel insult to persons in wheelchairs. Your regulations should
include language requiring designers to keep pedestrian access routes as flat as
possible and permitting exceptions only where other accessibility requirements
require an adjustment.
In addition, designers should be encouraged to introduce modest horizontal
diversions, where appropriate, to reduce the grade of a pedestrian access route.
Horizontal diversions should also be encouraged along routes that have a grade
in excess of 1:20 prior to any conflict points.
Section 1103
Pedestrian Access Route and stairs. As indicated above, stairs should be kept
out of the pedestrian access route. Where stairs may be desirable, the
pedestrian access route should be designed in such a fashion that the route that
employs stairs can be perceived as a secondary route.
Where grades make steps unavoidable and an elevator is required, the elevator
should be located in a convenient and obvious location requiring little
circuitous travel. Standards are needed, appropriate for public environments.
Section 1104.2.1.2
Cross slope. The reason for exempting mid-block crossings from the maximum 1:48
slope should be explained. I am assuming that at a mid-block crosswalk, the
cross-slope of the ramp should be the same as the slope of the gutter so that
the pedestrian route will not be warped. If that is the intent, it should be
stated.
Section 1104.3.1
Width. I strongly encourage you to require curb ramps or blended transitions to
extend for the full width of a crosswalk, if marked, or the full width of the
extending sidewalk if no crosswalk is marked.
A person needing the use of a curb ramp should not have to search for its
location but instead assume that a transition free of vertical change in level
will be available at the roadway edge. In a city, fighting to move at right
angles to the flow of pedestrians to the available curb ramp can be difficult
and/or dangerous. In suburban areas, the crosswalk should provide visual
guidance regarding the curb ramp location. See below regarding crosswalk width.
Section 1104.3.4
Grade breaks. As I understand this section, it applies only to grade breaks in
curb ramps and blended transitions. The first sentence indicates that grade
breaks are not permitted at curb ramps, blended transitions, etc.; the second
sentence says that when they do occur they shall be flush. Either grade breaks
are permitted or they are not permitted.
I obviously don’t understand the meaning of flush in the second sentence, and it
is not defined. I think that you mean that there shall be no change in level at
a grade break.
From a practical perspective, this will be very difficult to achieve. With
differential settling, differences of less than ¼ inch are bound to occur.
Furthermore, unintentional grade breaks are likely to evolve. Do these
exceptions become instantly in contravention of the regulations?
Section 1104.3.5
Changes in level. Similarly, although a project may be initially designed to
result in no changes in level, the requirement that different materials be used
in the sequence of devices described, curb ramps, landings and gutters, will
over time result in some changes in level evolving. What reasonable approach
should be permitted to allow minor, unintended changes in level but also require
greater changes to be corrected?
Section 1104.3.7
Clear space in crosswalk. I and many other designers are working to reduce the
length of crosswalks through the introduction of curb extensions and refuge
islands. These can be very beneficial to all pedestrians. What we are trying to
do is keep as much of the crosswalk as possible out of the roadway by narrowing
the roadway as much as possible.
The clear space within a crosswalk mandated by this section represents unneeded
roadway width. This section will prohibit curb extensions. Is that really your
intent? I strongly encourage you to revise this section. Please use the
regulations to encourage the practice of installing curb extensions at
crosswalks, not prevent it.
Section 1105.2.1
Width of crosswalks. The requirement that crosswalks have a minimum width of 8’
is another example of introducing a regulation aimed at dense urban environments
that would be impractical or counter-productive in other environments. It should
be more narrowly drafted.
Crosswalks in outlying areas are lightly used. While a downtown crosswalk may
have several hundred persons crossing every hour, even thousands, in suburban
areas we usually are talking about less than 100 per day. In this environment,
the crosswalk markings are serving a different function, and the potential of
conflicting pedestrian movements are very limited and easily overcome.
A major purpose of the crosswalk lines in these less traveled areas is to direct
pedestrians in the most advantageous and hopefully shortest route. The crosswalk
lines can be very helpful in guiding persons to the curb ramps on opposite side
of the street. They can also encourage pedestrians to cross at locations where
motorists will have the best sight vision of the pedestrians.
The wide width will restrict the utility of crosswalks in guiding pedestrians to
the available curb ramps. In my opinion, an 8’ width may reduce the visibility
of the crosswalk compared to a 6’ width, especially if transverse crosswalk
lines are used.
In heavily developed urban areas, on the other hand, crosswalk lines may need to
be wider than 8’. A procedure should be provided to guide designers in those
situations as well.
Section 1105.2.2
Cross slope. I recommend that you amend this language to specify that you are
speaking of the cross slope of the roadway, not the cross slope of the
crosswalk. I was very confused.
Section 1105.3
Pedestrian signal phase timing. As I understand this section, the draft
regulations are requiring that a 14% slower walking speed be assumed. In
addition, the regulations require that crosswalks be extended by 48” to provide
a clear space within the roadway, and this section requires that the pedestrian
clearance interval also include the length of the entire curb ramp, which often
are 5 to 10 feet in length.
The net effect of this section will be to create very lengthy pedestrian
crossing phases, necessitating longer traffic signal cycles. This in turn will
encourage more pedestrians to illegally cross outside of the pedestrian phase,
since they will grow impatient.
I agree with the reduction in assumed walking speed. However, agencies should be
allowed to retain other current procedures for timing pedestrian phases.
Section 1105.6.2
Signals at roundabouts. I strongly oppose this section. Roundabouts have many
features that are beneficial to all pedestrians, including those with
pedestrians. Most notably, crossing distances are substantially shorter, and
motorists have much better ability to see crossing pedestrians compared to
turning motorists.
Requiring pedestrian signals at all roundabout crosswalks will substantially
increase the cost of installing roundabouts. Since most pedestrians will ignore
the signals, finding the short crossing distances easy to negotiate, the use of
signals at these locations will breed contempt for traffic signals by
pedestrians. If pedestrian signals are activated frequently, traffic engineers
will develop lengthy signal cycles, frustrating pedestrians.
Instead, the Board should work with AASHTO and Federal Highway to develop
additional design guidance to enhance the visibility of crossing pedestrians and
to encourage yielding behavior by motorists. Consideration should be given to
using raised crossings or other traffic calming measures to slow drivers at
roundabout crosswalks.
If signals are to be required, there should be a volume warrant. As worded, this
section would apply to any roundabout regardless of its environment if
pedestrian crosswalks and facilities are provided. A neighborhood traffic circle
with less than 1000 vehicles ADT would have to have signal controlled crossings
even though no signal would be warranted without the circle and the circle would
enhance pedestrian safety and slow vehicle speeds.
At exurban locations, this requirement will encourage road designers to
eliminate crosswalks and sidewalks so as to avoid the requirement to install
pedestrian signals.
I recommend that the Board instead seek to develop a warrant based crosswalk
signal that would take into effect the volume of traffic using each roundabout
approach and exit, and the volume of pedestrian activity. On roundabouts with
high motor vehicle volumes but only limited pedestrian activity, a flasher
system should be required to alert motorists to the presence of pedestrians.
Finally, to the extent feasible, if pedestrian signals are to be introduced in
areas with roundabouts, it should be done in conjunction with other pedestrian
improvements that would move pedestrian crossing locations to mid-block sites
independent of the roundabout. From a land use perspective, this is difficult,
since it requires directing transportations away from their travel paths.
This is an area requiring much more research.
The proposal as presented is another example of introducing a regulation aimed
at a dense urban environment that would be impractical or counter-productive in
other environments. It should be more narrowly drafted.
Section 1105.7
Turn Lanes at Intersections. This section requires the provision of a pedestrian
activated traffic signal at any right or left turn slip lane. My comments
regarding roundabouts also apply to this recommendation.
The proposal as presented is another example of introducing a regulation aimed
at dense urban environments or suburban environments with intense vehicular
traffic; it would be impractical or counter-productive in other environments. It
should be more narrowly drafted.
Slip lanes are introduced for many reasons. One important one is to accommodate
the wide turning requirements of large vehicles with less pavement, especially
at intersections with acute angles. This is desirable for all roadway users and
can make pedestrian crossings easier to negotiate.
Slip ramps may be appropriate on low volume roadways if the roadways intersect
at a very acute angle or if there are large vehicles that use the intersection.
In this situation, a traffic signal could not meet any reasonable warrant; a
roadway designer would likely prefer to construct a wide, unchannelized
intersection rather than install a traffic activated pedestrian signal.
Even in urban locations, most pedestrians will ignore the pedestrian crossing
device unless turning volumes are both high and continuous.
Alternative designs for slip ramps are needed that improve a driver’s ability to
observe pedestrians and yield to crossing pedestrians. These improved designs
exist, and also substantially reduce crashes between motor vehicles. By
employing detectable warnings at crossing locations in combination with improved
slip ramps, the negative impacts currently experienced can be substantially
reduced. Use of rumble strips on slip lanes in advance of crosswalks should be
tested as a method of alerting persons with visual disabilities of the presence
of an approaching vehicle and would also alert motorists of the crosswalk.
Finally, there is a need to establish a warrant based system to determine when
pedestrian activated signals should be installed. I expect that this will
usually only be necessary when the volume of turning traffic exceeds 1000
vehicles in the peak design hour.
Section 1106.2.1
Location of pedestrian signal devices. I may be misinterpreting this, but I
think the last sentence should state that devices should be perpendicular to the
direction of the crosswalk it serves. A device parallel to the crosswalk could
not be seen. If I am misinterpreting your intent, others also will like do so.
Charles Carmalt