Mar 26, 2015

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In this seminar, Dr. Porter will explore the interactions of geometric design decisions, speed, and safety. A performance-based approach to this topic will be considered given the availability of several key documents, including the Highway Safety Manual and TRB's Modeling Operating Speed: Synthesis Report as well as a significant body of published research. A historical look at the design speed concept will show that while the design speed definition has changed on more than one occasion, the same basic but flawed philosophy that relates design speed to a “safe speed” is still reflected in supplemental guidance related to design speed selection in current design policy. A conservative approach to establishing design criteria, currently used to address the range of driver, vehicle, and roadway conditions and capabilities that a designer must consider, will be demonstrated. Resulting operating speeds will be shown to be higher than design speeds for design speeds of approximately 55 mph or less. This outcome may be considered undesirable from a safety perspective, but that categorization seems to be based more on...

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Mar 11, 2015

To be published later this spring is some of the first bicycle-focused research into shared space, a controversial urban design approach pioneered in the Netherlands in the 1990s.

Allison Duncan, a PhD candidate in urban studies & planning at Portland State University, earned a NITC dissertation fellowship in 2014 and used the research grant to study shared space intersections in the United Kingdom.

Shared space designs have recently been adopted at a handful of sites in the UK and others scattered across Europe, Australia and New Zealand. They are characterized by a lack of physical guidelines such as curbs, road surface markings and traffic signs to define who has the right-of-way.

The idea is for pedestrians, cars and bicycles to mingle in a common zone and use eye contact and natural communication to make sure no one gets hurt.

“Cyclists and pedestrians are supposed to be able to treat it more like a plaza and just cross where they want to, and drivers are supposed to yield,” Duncan said.

As a street design scheme, shared space isn’t exactly new. It’s more or less the way all streets were designed until the advent of cars, and is still the norm in many Asian countries where cars share the roads with a crowd of two- and three-wheeled...

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Jan 14, 2015

The video begins at 1:39.

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Jan 09, 2015

The video begins at 18:05.

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