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

Photo: Stephen 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.

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