Wider, Straighter, and Faster Roads Aren’t the Solution for Older Drivers

Photo: ##http://www.flickr.com/photos/t4america/4076272247/in/set-72157622516593443##Stephen Lee Davis/T4America##

This response to a new report from AASHTO and TRIP on safety issues for older drivers was written by Gary Toth, senior director of transportation initiatives for Project for Public Spaces, and co-signed by Congress for the New Urbanism, the WALC Institute, and Strong Towns.

The issue of safety and older drivers is an important one. And we are grateful for the way the special needs of those drivers are highlighted in a new report called “Keeping Baby Boomers Mobile: Preserving the Mobility and Safety of Older Americans.” Unfortunately, the report, produced by AASHTO (the American Association of State Highway and Transportation Officials) in collaboration with TRIP, a national transportation research group representing contractors and engineering firms, continues to reinforce the “forgiving highways” orthodoxy that the transportation establishment has been promoting for too long now. (On the positive side, it also endorses a number of measures that AARP has been pressing for: better signs, retroreflective paint, brighter street lighting, etc.)

What is remarkable is how thoroughly and blindly the profession has adopted these principles.

It is time for AASHTO, TRIP, and other members of that establishment to recognize the limitations of “forgiving highways” principles. This approach, which aims to reduce crashes by designing roads to accommodate driver error, might work well for interstates, freeways, and rural highways. But it should not be applied to the rest of our nation’s roads. Evidence is mounting that not only does the “wider, straighter, and faster” philosophy fail to fix safety problems on urban and suburban arterials — it actually makes them worse.

Let’s consider the issue of older drivers and safety from an engineering perspective. Engineering involves the practical application of science and math to solve problems, so we’ll take a closer look at the problem defined in the report and the applications suggested to address that problem.

On page 5, TRIP and AASHTO point out that left turns are of special concern because elderly people have more trouble making speed, distance, and gap judgments. These are all speed-related issues caused by cars going too fast through intersections. So what are the solutions proposed?

  • Widening or adding left-turn lanes and increasing the length of merge or exit lanes
  • Widening lanes and shoulders to reduce the consequence of driving mistakes
  • Making roadway curves more gradual and easier to navigate

In other words, make the roads wider, straighter, and faster. How will this help?

AASHTO and TRIP suggest that wider lanes will allow drivers more room to maneuver, but this “countermeasure” only comes into play once the circumstances that cause a crash are already in motion. Nothing in the report addresses how to avoid the crash in the first place. And as the report clearly points out, such crashes are caused by speeds that are too high to allow drivers time to judge other cars’ speeds, their distance, and whether there is enough of a gap to make a turn (this doesn’t just affect older drivers, either).

Sadly, this kind of thinking is not surprising. It is exactly what the transportation industry has been doing since the 1960s. Buoyed by research on why interstate highways were so much safer than other roads, transportation experts convinced Congress during the 1966 Safety Hearings to apply the wider, straighter, and faster concepts to all American streets. As former career safety engineer Kenneth Stonex testified: “What we must do is to operate the 90% or more of our surface streets just as we do our freeways… [converting] the surface highway and street network to freeway road and roadside conditions.”

What is remarkable is how thoroughly and blindly the profession has adopted these principles.

We clear our roadsides of “fixed objects” such as trees, light poles, and other objects, creating “clear zones” to bring vehicles to controlled stops if and when they leave the roadway. We flatten curves, shave hills, and place guiderail and concrete barriers to redirect cars that stray. We install rumble strips to alert drivers when they are moving into an area that the engineer has placed off limits.

While the mission is accomplished for vehicles that leave the roads, there is an unintended consequence: vehicular speeds go up. Paradoxically, more drivers do leave the road and there are more conflicts between drivers on the roads. And since speeds are higher, the consequences of crashes are far more severe.

Drivers respond to their environment. Put them on a stretch of road that is wider, flatter, and straighter and they will drive faster. Higher speeds may be okay on controlled-access freeways with no adjacent land uses or pedestrians, where sight distances are near infinite, curves are flat, and opposing roadways are separated by wide medians or center barriers. But those speeds don’t translate well to other environments.

We were so caught up in the idea that we were doing the right thing by building wider, straighter, and faster, that until recently we never stopped to check to see if we were getting the desired result. It is now clear from the evidence that higher speeds on all roads except freeways make us less safe. Research by Eric Dumbaugh [PDF] and evidence gleaned from the Netherlands Sustainable Safety program reveals that the key to safer non-freeway roads is slowing down traffic to speeds appropriate to context.

We understand that the concept that slower can be better is unpopular in a number of AASHTO’s member states. Rural and developing states incorrectly equate the idea of matching speeds to the context with “no more big roads to help us grow.” But if AASHTO wants to maintain its status as the “Voice of Transportation,” it needs to lead the industry into the 21st century.

The Federal Highway Administration (FHWA) has already demonstrated this leadership. Its office of safety has produced a website to highlight proven countermeasures. Three of the top nine recommended measures involve approaches that either slow down vehicles and/or reduce the number of conflicts. None involve the 1960s approach of making roads wider, straighter, and faster. Similar recommendations are made on the FHWA Livability website.

There are other examples of respected members of the transportation industry acting proactively in the absence of leadership by AASHTO. In the “Smart Transportation Guide,” Pennsylvania and New Jersey DOTs provide guidance to their engineers on how to use design to slow down vehicles when appropriate for the context. The Institute of Transportation Engineers and the Congress for New Urbanism do likewise in their guide, “Context Sensitive Solutions in Designing Major Urban Thoroughfares for Walkable Communities.”

It is time for AASHTO to focus attention on the mounting evidence that arterials, collectors, and distributors need different solutions than freeways. High-speed roads in built-up areas not only decrease safety, they decimate the value of adjacent places, communities, and land use (as is so well said by Chuck Marohn of Strong Towns).

To address the needs of older drivers, AASHTO should be calling for design concepts that:

  • When appropriate, slow down speeds to improve the ability of drivers to properly perceive speeds, distances, and gaps. See FHWA countermeasure for road diets and roundabouts.
  • Eliminate the weaving and merging caused by multilane roads that are over capacity for all hours except perhaps the peak hour. See FHWA countermeasure for road diets.
  • Eliminate the conflicts caused by a wide range of speeds created by road sections allowing some drivers to pass through at high design speeds in the same cross-section where others are slowing to enter or exit the roadway. See FHWA countermeasure for corridor access management.
  • Eliminate the Safety Problems created by left turns on arterials, collectors and distributors. See FHWA countermeasure for roundabouts.

TRIP should embrace these solutions as well. Yes, it is an organization representing highway contractors and large engineering firms. But there will be as much money in building and designing roundabouts, road diets, and revamped access management as there would be in wider, straighter, and faster projects.

The end result would be truly 21st-century roads that are safer for older drivers — and for everyone.

23 thoughts on Wider, Straighter, and Faster Roads Aren’t the Solution for Older Drivers

  1. I have to disagree with you on the widening shoulders part.  In my experience back home in Minnesota, widening shoulders gives a multi-modal benefit:  it gives bicyclists a place to ride (and in MN, they do!), and buses can utilize designated shoulders during periods of congested traffic.

  2. I’m glad roundabouts are mentioned here. I feel they should be the default way to deal with intersections unless lack of space prohibits them.

  3. We have to be careful not to confuse these recommendations — for more exurban and rural roads — with urban and relatively dense suburban roads.  Sometimes a speed hump and raised crosswalk are what you need.

  4. Hi Adam

    Your point is well taken about shoulders.   I was reacting, however, to the TRIP/AASHTO report that recommended increasing shoulder widths as a countermeasure to the perils of senior drivers having trouble reacting to gaps and speeds of other cars.   I am a fervent believer of Context Sensitive Solutions that respond to the needs of all road users, so yes, in the bigger picture street and road solutions should address bicyclist needs as well.

  5. “Scripts like these are insurance policies against disaster. And they prevent disaster. But what they assure in its place is mediocrity.” 

    We need more wisdom in planning, knowing when to break “rules”. I couldn’t agree more with Gary’s point here about not blindly following established rules of the past 30+ years. Our current reality demands a giant shift in thinking. Organizationally departments will have to break a lot of “rules” as they shift to a new paradigm more centered on sound human-scale factors.  For more on this quote about practical wisdom, watch this great TED talk: http://www.ted.com/talks/barry_schwartz_on_our_loss_of_wisdom.html

  6. @2555783a6f62598b6aadd2d882a4830f:disqus Roundabouts should rightly be considered in places where pedestrians don’t matter. But in towns and cities, pedestrians rule, and should have veto power on roundabouts.

    That being said, I like a left turn lane now and then.

  7. @36056f95783f8cfb512e9d49d4187ce6:disqus Aren’t roundabouts safer for pedestrians as well? Cars are forced to go much slower, plus there is only one lane of traffic to cross. There’s absolutely nothing inherently pedestrian safe about traditional intersections, signalized or not.

    If pedestrian density is really high, just keep cars out altogether, and/or grade separate them. 

  8. @2555783a6f62598b6aadd2d882a4830f:disqus I don’t know whether they are safer or not for pedestrians. I do know that they are less convenient, since you are not walking in a direct path.

    As far as grade separation environments with high pedestrian density, I have no problem with drivers having to get out of their vehicle, put it in neutral, push it up a flight of stairs, walk it across a bridge, carry it back down the stairs, and then get back in and resume their trip. I assume that’s what you mean by grade separation, right? 🙂

  9. @36056f95783f8cfb512e9d49d4187ce6:disqus It depends how you define convenience. Waiting a minute for a walk signal every block or two, as is often the case with busy intersections in a place like Manhattan, seems decidedly more inconvenient to me than having to divert maybe 10 feet from a straight path at every intersection.

    Grade separation could mean any of a number of things. Don’t always assume the pedestrians are the ones to change elevation. You could just as easily bring the roads above or below grade level in the busiest places. Or just ban cars altogether. It wouldn’t kill anyone if they have to park a few blocks away. By the looks of them, most people in this country could do with a bit of exercise anyway.

  10. AASHTO’s safety standards are based on statistically proven fact that roads with gentle curves and shoulders have fewer accidents. 

  11. @2555783a6f62598b6aadd2d882a4830f:disqus  I’m confused—how are roundabouts ever safer or more convenient for pedestrians?!

    My experience with roundabouts (mainly in the UK) is that even very small ones are absolutely miserable for pedestrians, because one still has to cross the roads which feed the roundabout, and unlike a traditional intersection, the traffic feeding a roundabout never really stops.  Even if drivers have to temporarily stop to enter the roundabout, they’re still very much in “go” mode, and we all know how aggressive that often makes drivers.  For a pedestrian, it’s frightening, and I wouldn’t be surprised to find out it’s dangerous as well.

    On top of the go-go-go vibe, the mere size of roundabouts screams “this space was meant for cars.”

    Roundabouts seems like yet another dopey idea that makes traffic flow more efficiently but has an overall negative impact on the urban environment.  Our society should not be designed by traffic engineers.

  12. @google-9ed3368a6439fa92efd353af4436290d:disqus I’m curious then exactly what solution you feel is better than roundabouts. The beauty of roundabouts is they force a slow speed at intersections by virtue of their geometry. This makes it quite a bit easier for a person crossing to determine when to cross, assuming motor vehicles fail to yield to them as they’re supposed to. You’re only crossing one lane of traffic at a time, so you’re concerned solely with one direction of traffic at a time. In the event a car does strike a pedestrian, chances are good it will only be traveling 10 or 15 mph, meaning the person likely won’t suffer severe injuries. Note here that I’m talking strictly about single lane roundabouts. Multilane roundabouts aren’t really pedestrian friendly, but those probably wouldn’t be used in an urban environment anyway.

    Compare this your traditional intersection. If you put stop or yield signs up, chances are good the driver is still in “go” mode. Even if it’s signalized, a person crossing still could face a continuous stream of turning cars (turning both left and right) which are in “go” mode. Yeah, you could start with all sorts of fancy light cycles, turn signals, and other bs, even stop all traffic when pedestrians cross, but this comes at the cost of huge delays for everyone, including pedestrians. And it still doesn’t make anyone safe. You’re depending upon people to honor a red signal. Even with good intentions, 100% compliance is impossible because humans make mistakes. There’s absolutely no physical barrier preventing a motorist from blowing a red light at 75 mph and hitting a pedestrian. When you put up huge numbers of these silly signalized intersections, as NYC has done, then compliance goes way down, especially among pedestrians and cyclists, because the time cost of compliance for these two groups is way too high. When that happens, you’re basically back to people looking for gaps in traffic and crossing when they determine it’s clear. That’s pretty much what happens at roundabouts, except that the cars won’t be doing 50 mph through the intersection like they often do in NYC.

    The only really pedestrian friendly solution is to either grade separate, or just get rid most of the cars. Roundabouts are better than the alternatives, but they’re not a panacea by any means. I’m thoroughly convinced that anything beyond a very light volume of motor vehicles is simply incompatible with heavy pedestrian traffic.

  13. While I generally agree with your questioning of arterial roads being wider, straighter,faster  there is one road where I live that I consider dangerous.  There are many sharp, blind curves and few stop streets.  Some drivers will not slow down enough for the curve and thus go over the center line.  The hilly road has no shoulders.  A head on collision is just waiting to happen if it hasn’t already. 

  14. @2555783a6f62598b6aadd2d882a4830f:disqus One thing I’ve seen is “semi-roundabouts”, which are the same as a normal intersection in operation, but physically shaped like a bit like a roundabout—with a big center-obstacle in the middle of the intersection and the actual lanes bowed out around it.

    The effect is that you get the “OMG I gotta slow down” effect of this big obstacle, plus the stoplights or whatever to further control traffic in the traditional manner.  Note that the lane shape isn’t a pure circle like a real roundabout, more like a square with curved sides, so it doesn’t communicate the “go go go” feeling of a roundabout; there are angles to be contended with.

    After all the real problem with a roundabout is the message it sends, that “traffic doesn’t need to stop.”

  15. @2555783a6f62598b6aadd2d882a4830f:disqus  Re: “I’m
    thoroughly convinced that anything beyond a very light volume of motor
    vehicles is simply incompatible with heavy pedestrian traffic.”

    Maybe that’s true, but of course if you’ve already got heavy vehicle traffic and heavy pedestrian traffic, you’ve got to do something, and in the short term you may not have the option of simply getting rid of vehicles…

    In fact I’ll bet that heavy pedestrian traffic actually makes things a bit safer for pedestrians, because it forces the issue: drivers can’t just ignore pedestrians when there are massive quantities of them.  Designs like “scramble crossings” help as well, by further emphasizing the primacy of pedestrians.

    The real danger seems that in areas with big roads and only light pedestrian traffic, like many U.S. suburbs, where cars get the feeling that they can just floor it, and are rarely reminded that they should be careful, and where it may be politically more difficult to interfere with car traffic…

  16. I’m happy to hop on the ‘orthodoxy’ criticism bandwagon, but I guess I’d like to see it go both ways. 

    Tonight I talked to someone who has actually ridden the Bogota Transmilenio BRT — it’d be nice if we could get ‘progressives’ to actually question ‘orthodoxy’ on BRT.

    Kettle black?

  17. @google-9ed3368a6439fa92efd353af4436290d:disqus Your operative assumption about roundabouts not being safe for pedestrians is based on the idea that there is an unending stream of traffic with no gaps, and that motorists will never yield to pedestrians. Maybe you always crossed those roundabouts in the UK at the height of rush hour? The reality of the situation is that even in places like Manhattan, there are frequently large enough gaps in traffic for a person to cross, even on the wider, busier avenues. As for yielding to pedestrians or not, this seems to be ingrained in the culture of a place. It’s an entirely separate issue from how to treat intersections. Remember that even traditional intersections generally require motorists to yield to pedestrians when making some movements.

    One thing we both seem to agree on is that traffic should be physically slowed at intersections somehow by the geometry of the intersection. This at least makes the consequences of any failure to yield much lower.

    How to deal with pedestrians is indeed a large problem in places where there are much fewer of them, and heavier motor traffic. The big problem with things like signalized intersections, besides the fact that they really don’t make things any safer, only give the illusion of safety, is that they make things really bad for cyclists on many levels.

    I submit that in suburban or semi-suburban areas (i.e. much of the outer boroughs in NYC), roundabouts would actually make more sense precisely because they’re much, much better for cyclists than traditional intersections. If you add in bike lanes, this could have the effect of essentially turning the majority of pedestrians in these areas into cyclists, pretty much making the pedestrian problems moot. When you look at countries like the Netherlands, it’s fairly apparent that in many places the accommodations for pedestrians are poor or nonexistent. This isn’t because they don’t care about people who walk. Rather, it’s because outside of in towns or more crowded parts of large cities (both of which often severely restrict cars), people generally bike rather than walk.

    What it comes do to is I personally don’t care whether or not we make auto traffic flow more efficiently, but I do care about making bicycle traffic flow more efficiently. Many of the ideas NYC currently uses to improve the “pedestrian experience” make cycling absolutely miserable. Needing to stop and wait 60 seconds every 2 blocks (or more realistically just treating the red like a yield sign) doesn’t qualify as cycling in my mind. It might not be that bad if you only experienced nonsense like this over a small portion of one road where there was very heavy pedestrian traffic. That’s not the case. You often have roads with lights on every block or two for miles. In the outer boroughs these lights are rarely synchronized. The red cycles are usually based on how long it takes a fairly slow walker to cross. There is no provision to actually detect if someone is in fact crossing. Bottom line-if you’re going to use lights with very long cycles for crossing pedestrians, then at least have a pedestrian detector or push-to-cross button so the light only goes to a longer cycle when necessary (and you could even do this at the entrance to busier roundabouts). I personally think it’s ridiculous to force anyone to wait and stare at empty space. That’s really the single biggest problem with signalized intersections. It’s also the reason red signals often aren’t honored, effectively making this type of traffic control mostly useless. Roundabouts at least force motorists to slow down to bicycle speed at intersections, making it at least somewhat more likely they’ll see and yield to people crossing.

  18. Thank you, Gary, for such a carefully considered response to this report, and one that strikes the theme of prevention as superior to mitigation.  I also wanted to note that AARP’s dialogue with engineers on highway design is ongoing; the report they issued as part of their work with the National Complete Streets Coalition, “Planning Complete Streets for an Aging America”, takes direct aim at the fallacy of wider/faster/straighter and helped push FHWA in a new direction.  

  19. Streetsblog hits the nail on the head with this one. Amazing analysis man, I couldn’t agree more, they aren’t seeing the forest for the trees on this one. All this will do is create more dead bicyclists and pedestrians many of whom will be elderly.

  20. AASHTO seems to be a source of a lot of the backwards, 1970s design and thinking that prevents complete streets.  It would be great if Streetsblog would do a profile of the people on the key AASHTO committee who are making these decisions. 

  21. Where do they get these transportation “experts”?  Anyone who’s studied road design knows that the straighter and wider a road or street is, the faster the average driver will go and the more dangerous it will be for older drivers.

    Even if you ignore pedestrian and bicycle concerns, the last thing older drivers want or need is to be surrounded by faster moving traffic.  That’s why so many of them avoid the freeways and expressways.   At faster speeds, reaction time is more critical–and reaction time is something that declines significantly as we age.  Declining vision also makes it hard to judge speed of cross traffic before pulling out or changing lanes.  Faster speeds give you less margin for error.

    The stereotype of the senior citizen driving 20 mph down a street where everyone else drives 35 is real.  Slower is safer for seniors (and everyone else around them).  And they know it.

  22. Here’s an even more radical idea: a maximum driving age. We as a society already imposed a minimum driving age because we decided that people under 16 are unlikely to have the cognitive, sensory, or physical capacity.

    Well, around age 80, most of us experience a measurable decline in cognitive, sensory or physical capacity. If we stopped renewing licenses past this age, we would save a lot of agony in families where Mom or Dad is a hazard on the road but the kids don’t or can’t intervene.

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