July 31, 2015


As Americans Figure Out the Roundabout, It Spreads Across the U.S. (ERIC A. TAUB, 7/31/15, NY Times)

Once seen only in countries like France and Britain, the roundabout, favored by traffic engineers because it cuts congestion and reduces collisions and deaths, is experiencing rapid growth in the United States.

First built in the United States in the early 1990s, roundabouts have doubled in the last decade, to around 5,000 today, according to Richard Retting, a former transportation researcher at the Insurance Institute for Highway Safety. "There are hundreds if not thousands more in the planning stages," he said. [...]

Roundabouts are not the same as traffic circles. Columbus Circle in Manhattan, for example, is a traffic circle; vehicles have the right of way based on when their light turns green.

But roundabouts typically do not have traffic lights; instead, a vehicle approaching one slows to around 20 miles an hour and yields to those already in the circle.

New Jersey has gradually been replacing traffic circles with roundabouts. At trouble-prone intersections, "one of the options given serious consideration would be a modern roundabout," said Kevin Israel, spokesman for the New Jersey Transportation Department.

Compared with stop signs and traffic lights, roundabouts are significantly safer, engineers say. For example, crashes that result in serious injuries or death are reduced by 82 percent versus a two-way stop, and by 78 percent compared with an intersection with traffic lights, according to Jeff Shaw, the intersections program manager for the Federal Highway Administration.

Mr. Retting of the insurance group said that the reduction in injuries and fatalities was "unmatched by anything else we can do in traffic engineering."

Unlike standard intersections, drivers cannot speed across a street and hit a vehicle in the perpendicular lane; instead, they must slow and merge with others in the circle. Left turns in front of oncoming traffic are eliminated. And because vehicles never come to a complete stop, less fuel is consumed.

Elon Musk: Tesla 'almost ready' to go driverless (Cludia Assis, July 31, 2015, Marketwatch)

Elon Musk has test-driven Tesla's next software update, which will enable cars to steer themselves on highways and parallel park. [...]

The Model S cars have built-in driver-assistance systems that include, among other things, forward radar, a camera mounted by the rear-view mirror, and 12 sensors that can sense objects within 16 feet of the car. Tesla is able to release over-the-air software updates so owners don't have to bring their cars in for service.

The road to autopilot driving has been incremental. Last year, Tesla launched features such as lane-departure warnings, and earlier this year it released adaptive cruise control, blind-spot warning, and a forward-collision warning system.

Posted by at July 31, 2015 5:32 PM

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