Topics: Americans with Disabilities Act: Accessible Road Design.
Talking Traffic Episode 7 – Americans With Disabilities Act: Accessible Road Design
Hello, and welcome to Talking Traffic, the podcast that discusses mobility and connectivity issues. My name is Bill Ruhsam and today is Tuesday, Novemeber 27th, 2007. This is episode 7 of talking traffic and it is a sequel, of sorts, to episode 6. Episode 6 was about pedestrian facilities along roadways. This episode will be about making those pedestrian facilities accessible to people who are visually, aurally, or mobility impaired.
I’m betting that you do not fit into any of the three categories I just mentioned. This has nothing to due with psychic ability and everything to do with statistics. 70% of Americans will be significantly impaired at some time in their lives, but those conditions are usually not permanent, or recurring. Only 20% of Americans over 15 years old have a permanent disability. Because of this disparity, construction and engineering design did not take into account the needs of the less-mobile or sense-impaired person. Thus, the Rehabilitation Act of 1973 and its more famous successor, the Americans with Disabilities Act of 1990, or ADA.
The ADA has a 5 titles, but in my work, I’m usually only concerned with Title III, Public Accommodations and Services Operated by Private Entities. This title deals with access to public and publicly accessible private facilities. Again, I usually only deal with a small subset of this, access on public roads. To sum up, the ADA says, “Public Access for all persons will be guaranteed.” It doesn’t say that every facility everywhere has to be accessible, but for day to day work, it means that new construction must be usable by the disabled.
The ins and outs of the ADA and how it affects public accessibility are way outside the scope of this podcast, even if I were an accredited expert on the topic. Suffice to say that there are regulations that public roadways have to comply with in order to provide an accessible pathway for pedestrians. No compliance, no federal funding, plus the bonus of being sued by the disabled community. But, what is an accessible pathway? “Access” means that there are no barriers either physical or informational in the path of a pedestrian. Unfortunately, as I mentioned above, there are different types of disabilities, which bring different types of barriers into play. Let me paint you a scenario and then we’ll discuss how variously impaired persons handle it. Imagine a typical suburban signalized intersection. Four approaches with four crosswalks. The roads are one lane in each direction, and there are right turn lanes for each approach at the intersection. Because of the right turn lane, the corners of the intersections are rounded to a wide radius. This is done to maximize the flow of vehicles. So, we have four crosswalks at right angles to each other, extending across three lanes (a right turn, a through, and the opposite through lane), and the crosswalks are not extending straight off from the curb, instead they come off of the curve radius at a slight angle. There are sidewalks behind each curb, with a 6 foot grassy strip between the curb and the concrete. Pedestrian ramps lead from each sidewalk to each crosswalk. See the show notes for a diagram of what I just described.
What are the consequences for some common disabilities? Let’s start with a hearing impaired person. This person, in order to navigate the intersection, must come to the curb line at the cross walk, wait for a pedestrian signal (we’re ignoring any pedestrian pushbuttons in this scenario), visually confirm that there are no crossing vehicles, then proceed across the road. This is the best case for an impairment as most drivers will take eye-contact as an acknowledgement that a pedestrian has seen them, and vice versa. Our roads are built emphasizing the visual sense, so a hearing impaired pedestrian doesn’t have too bad a time. They don’t need to use the ramp, or even the sidewalk, having no physical disabilities. They can step off the curb and move across the street with ease.
A blind individual wouldn’t need the ramp either, but would need an audible cue of some sort in order to know when it’s safe to cross the traffic stream. Usually, with no beeping pedestrian signal, a blind person will listen to the crossing traffic, and wait for the vehicles moving parallel to them to go before trying to cross the sidewalk. Now we are presented with some issues. The left turners that are moving with the blind person are going to cross the path of the person, potentially when he or she is in the cross walk. A practiced visually impaired person will know this, and listen for it, but it’s a problem. Also, a blind person will use the curb (not the ramp!) to direct them across the roadway. A typical use of the pedestrian ramp by a blind person will be for them to find it, then move to the side and stand on the curb, making the assumption that they are pointing directly across the roadway. However, if a curve radius is wide, so wide that it extends well past the ramp, then the blind person is now pointing out directly into the intersection. Two obvious solutions to this problem are to either shorten the curve radius, or push the pedestrian ramp all the way out to the end of the curve. The first will reduce vehicular capacity at the intersection and the second generally moves the stop bar so far back that it’s impractical and unsafe for the vehicles. Back to that in a moment.
A physically impaired individual consigned to a wheelchair or scooter needs the ramp in order to get from the sidewalk to the road surface, and don’t forget that they need a well maintained sidewalk too! The wheelchair-bound person is going to have difficulty on hills and slopes because those wheels want to roll downhill. If you think this is no big deal, I suggest you find a wheel chair and try pushing yourself across a 2% slope and see just how hard it really is. 2% is the typical cross slope of a well-build sidewalk, by the way. Now, try a 5-10% cross slope which is what a lot of commercial driveways have where sidewalks pass over them. It’s hard to keep in a straight line.
Let’s not forget about physically impaired people not using a wheelchair. Someone using a walker will avoid that pedestrian ramp like the plague. Trying to go down a 8% slope (which is maximum for ramps) with walking impairment just doesn’t work. Here’s another person who will go to the curb and use the walker to help step down, or up. This person, along with the visually impaired, will need a portion of the sidewalk paving to extend up to the curb on the left and right of the pedestrian ramp. They will also be much slower than a non-impaired pedestrian, which means they need more time on the pedestrian signal in order to cross the road safely.
That was four types of disability, and notice that if you have a deaf person using a walker, things get much more difficult. Truthfully, I’ve just skimmed the surface of roadway accessibility by talking only about a signalized intersection. There are also considerations for the slopes of sidewalks, how long you can go on a slope before you have to provide a resting area, needs for hand rails and stairs, audible pedestrian crossings, locations of pedestrian pushbuttons, the list goes on. I will emphasize that some of the design features I mentioned for the above disabilities are mutually exclusive, and even mutually contradictory! What helps a blind person will not help a person in a wheel chair. And then there is the consideration that (again, generally) what helps pedestrians will hurt vehicular capacity. Longer pedestrian green times mean shorter green times for the cross street. Listen to episode 6 for a good description of that phenomenon. Shorter curve radii mean shorter crosswalks and ramps that are perpendicular to the curb, but slower right turns for the vehicles. There are also features that can be emplaced which directly help pedestrians at the expense of vehicles, like curb bumpouts at intersections, speed humps, midblock crossing signals, etc. These fall under the topic of “Traffic Calming”. The decision to emphasize one mode of travel over the other, pedestrians vs. vehicles, is one that vehicles have historically won outside dense urban areas in this country, but that is altering in the current climate. There is a realization that pedestrians are there and won’t be leaving, that we can’t build our way out of congestion, and that density is the wave of the future for urban redevelopment.
A topic for a future podcast is something called functional classification. This is the determination, through planning and discussion, about whether a road should be more mobile, or more accessible. This directly affects pedestrians because a higher functional classification roadway, such as an Interstate Highway, will have less, or zero, pedestrian access, while a lower functional class road should provide lower speeds, and significantly more friendly pedestrian access. It is in the discussion of functional classification that the negotiation between mutually exclusive pedestrian or vehicular elements should take place. Proper planning will allow for a network that serves all users, either in vehicle or on foot (or bike).
The last two talking traffic episodes have been devoted to pedestrians. I think the next one will need to talk about vehicles of some sort. Perhaps we can discuss signal inductance loops! Or maybe signal detection procedures in general. I’m not sure. John S. left a comment on one of the Traffic Tidbits asking about how motorcycles are treated by the road design community. He says “I’ve read a couple of articles in Motorcycle Consumer News by Fred Rau that tie in with your last podcast on intelligent transportation system design for pedestrians, but state that system designers are leaving out motorcyclists… Can you confirm or deny this?” Well, John, I can’t either confirm or deny. I will look into it and get back to you.
Thanks for listening. As always, if you have any comments or questions, or suggestions for future topics, please send me an email at bill@talking traffic.org, or leave a comment at www.talkingtraffic.org. This episode is released under a creative commons license for attribution, non-commercial, no derivatives. I’m thinking about re-releasing all previous episodes without the no-derivatives part. I want to insure that in the unlikely case someone wants to pull apart this podcast for future use, they can do so easily. Although there is nothing stopping people from asking me directly. More than likely, I’ll issue permission without much hesitation. For now, though, please tell your friends, and even give them copies, but don’t sell the podcast, don’t change it, and please credit me and talkingtraffic.org. The music on this podcast is by Beight, which is not pronounced, or spelled, like a loop in a rope as I said on the last podcast. They can be found at magnatune.com.
Enjoy your last week of November and remember to look both ways before crossing the road. And seriously, go try out a wheel chair on a sidewalk and you’ll have a whole new appreciation for the wheel-chair bound.
Example Intersection Layout: