Multi-lane roundabouts introduce several types of crashes that are not possible at single-lane roundabouts. There are new design possibilities to increase safety for all road users.
DOTs
The troubles with traffic forecasts
A new Vice report analyzes transportation models ―conceived more than fifty years ago in the early days of national highway building― as the “broken algorithm that poisoned American transportation.”
Roadway Design is Often Responsible for Driver Error
A new study shows that drivers do not make choices through conscious, intentional decisions but instead through the inference of expected behavior based on the roadway type.
NACTO releases safe speed limit guidance
As the transportation field gradually moves away from its singular focus on high motor vehicle speeds and its reliance on motorist behavior to set speed limits, NACTO has just released comprehensive guidance on speed limits on surface streets in metro areas.
85th percentile rule was supposed to be a starting point in setting speed limits
The longstanding tradition of setting speed limits at the 85th percentile of observed vehicle speeds is increasingly under scrutiny, with some agencies moving away from it. A new paper from Brian Taylor and U Hong …
California highway projects face review for induced travel
The implications of California’s SB 743 (2013), which is widely if somewhat imprecisely known as the “move away from level-of-service to vehicle-miles-traveled bill,” became clearer last week, as Caltrans issued guidance on which transportation projects will require evaluation for VMT effects.
Destination access bills introduced in U.S. House
A trio of U.S. House members along with 10 co-sponsors have introduced a pair of bills that would set destination access as a national performance measure. Both bills describe destination access, aka “accessibility,” in terms of travel times by auto, transit, walking, and biking, with consideration for traffic-stress levels on the active modes. One of the bills focuses on access to employment, while the other focuses on access to non-work destinations such as shopping and schools.
Planning for an uncertain future
Traffic forecasts and other projections are often presented as a single line on a graph or number in a chart. But we know—now more than ever—that these predictions are full of uncertainties. The Sacramento Council of Governments (SACOG), for a new study in JAPA, puts hard numbers to some of those uncertainties in order to plan better for them.
Sweden and Virginia: Messaging and variable tolls can influence mode choice
Two recent studies demonstrate two approaches to reducing driving. A Swedish study looked at what types of messages influence the choice to drive, while a report from Virginia shows that tolls on the I-66 corridor outside Washington have made a difference in both mode choice and when drivers travel.
Framing resilience for state DOTs
The mission of many state DOTs has evolved beyond the traditional “highway department” to include protecting the quality of life of the people of a given state, and the integration of all travel modes to safely move people and goods. Resilience has come to mean more than the quick and cost-effective restoration of roads after a disaster. Acknowledging this, a new paper in Transportation Research Part D focuses on resilience in theory and practice, and explores a framework for the discussion of resilience within state DOTs and the development of resilience strategies.