Portland State University

When engineers focus on transportation systems, they often produce brilliant solutions. Sometimes, however, they focus in the wrong place.

 “Engineers are really good; if you tell them, ‘This is what we want to accomplish,’ they’ll do it,” said Peter Jacobsen, himself an engineer and a public health consultant. “But traffic safety hasn’t had a good scientific, evidence-based approach that we have in, say, nuclear-power-plant design.”

Jacobsen, Portland State University’s first visiting scholar this school year, will present the Vision Zero concept at Friday’s transportation seminar. Vision Zero resets the goal of transportation systems from reducing total crashes to eliminating fatalities.

“The way engineers currently look at the road system is to look at crashes,” Jacobsen said. “Vision Zero folks say to look at health: not to have fatalities or permanent disabling injuries.”

Designing for health means respecting the limits of the human body. If crossing into oncoming traffic could produce head-on collisions with a greater force than people could survive, then Vision Zero says to separate that traffic. Roundabouts reduce the likelihood of dangerous side-impact collisions.

Vision Zero could have the largest effect closer to home. Jacobsen has pushed for colleagues to consider traffic from a child’s perspective. A residential street that might be...

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The video begins at 6:34.

Summary: The most recent edition of the Highway Capacity Manual (HCM) contains analysis procedures for measuring the level-of-service (LOS), also referred to as quality of service, provided by an urban roadway to bicyclists. The method uses different design and operating features of the roadway segment (e.g. width, motor vehicle volumes and speeds) to assess an LOS grade of A (best) to F (worst). These procedures are used by planners and engineers to recommend how existing streets could be retrofitted or new streets designed to better serve people on bicycles (and other modes). However, the current HCM does not include methods that address protected bike lanes (aka “cycle tracks” or “separated bike lanes”), only conventional striped bike lanes, shoulders, and shared streets. There are other methods for predicting comfort from a bicyclist’s perspective that do consider protected bike lanes, but they are either based only on expert opinion or on surveys in Denmark.

This presentation will describe how to evaluate the level-of-service of a protected bike lane using results from surveys conducted in the United States. The model developed by this project could be used to supplement the current HCM to objectively consider a wider...

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The video begins at 3:48.