Study: AASHTO Guidelines for Bikes Outdated, Not Based on Research

In a shock to no sustainable transportation advocate anywhere, a new study from the Harvard School of Public Health shows that the American Association of State Highway and Transportation Officials (AASHTO), the go-to resource for transportation engineering guidelines, holds antiquated views on bicycling facilities.

Specifically, AASHTO has repeatedly failed to support cycle tracks, also known as physically-separated bike lanes, in its recommendations for bicycling facilities, despite evidence that they’re safer than simply painting bike lanes on roads. In addition to examining five bicycling guidelines published between 1972 and 1999, the study examines 19 cycle tracks in the United States and found that the overall crash rate was safer than published crash rates on roads without bicycling facilities—2.3 crashes per 1 million bicycle kilometers on cycle tracks, compared to 3.75 to 54 crashes per million kilometers for bikes on roads.

The study also finds that AASHTO’s lack of support for expanded bike facilities has reduced cycling rates among women. Most women, children and seniors prefer cycle tracks because they feel more comfortable riding in a bike lane that is physically separated from traffic. AASHTO’s omission of cycle tracks has resulted in relatively few cycle tracks being built throughout the United States, resulting in fewer female cyclists. Only 24 percent of those who use a bicycle to get to work in the US are women, compared to the Netherlands — which has 29,000 kilometers of cycle tracks — where 55 percent of total bike trips are taken by women. The study also notes that in 1999, over 97 percent of the authors of AASHTO’s guidelines were men.

Despite the fact that a bicycle facility guideline written in 1972 endorsed cycle tracks and cited 68 references to back up that endorsement, AASHTO has repeatedly advised against cycle tracks due to alleged “safety” problems. AASHTO’s justifications have included conflicts with pedestrians crossing the lanes from the curb to parked vehicles, conflicts with intersections or driveways, and hazards created by the opening of passenger doors. Over the course of four different manuals—in 1974, 1981,1991, and 1999— AASHTO has only cited one research-based citation to back up these claims. In contrast, research by the New York City Department of Transportation shows that on 8th and 9th Avenues, where the City installed its first protected cycle tracks, not only were total crashes reduced between 13 and 23 percent, but injuries were reduced for cyclists and all other users of the roadway between 18 and 58 percent.

The study concludes that future bicycle guidelines should be based “on rigorous and up-to-date research” relating to safety and cyclist preferences, which runs counter to AASHTO’s approach. Although the study was completed before the release of AASHTO’s 2012 guidelines, lead author Anne Lusk e-mailed MTR the following statement: “On page 4-16 of the 2012 AASHTO guidelines is the below text which duplicates the prior text all the way back to 1974. There are no citations to back up the assertions.”

Bike lanes should not be placed between the parking lane and the curb.  Such placement reduces visibility at driveways and intersections, increased conflicts with opening car doors, complicates maintenance, and prevents bike lane users from making convenient left turns.

In other words, AASHTO is still printing the same unsupported arguments they were hawking 30 years ago.

1 Comment on "Study: AASHTO Guidelines for Bikes Outdated, Not Based on Research"

  1. Yes, but NACTO guidelines are only a little bit fresher! See

    Unfortunately the unfortunate truth is that Janette Sadik-Khan is the chair of that org. She does good things but well-meaning experts don’t challenge her enough — I realize that lack of political support and consensus blocks Dutch state-of-the-art, but sustainable transport activists are loathe to admit publicly that NACTO guidelines are second-rate. This is a huge problem which slows the push towards better conditions.

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