Jul 22, 2009

traffic circles expanding their circumference of power

I commute through downtown Olympia every (school) day, driving 'round two roundabouts as I head up 4th/Harrison toward Capital High School. While they used to be somewhat treacherous, as inexperienced drivers struggled to learn right-of-way rules, or keep their SUVs in one lane, over the years, the two traffic circles have become easier and easier to negotiate.

Monday I linked to an article by Tom Vanderbilt explaining why roundabouts are superior to traditional four-way intersections. Consider safety:
Roundabouts are safer than traditional intersections for a simple reason: By dint of geometry and traffic rules, they reduce the number of places where one vehicle can strike another by a factor of four. They also eliminate the left turn against oncoming traffic—itself one of the main reasons for intersection danger—as well as the prospect of vehicles running a red light or speeding up as they approach an intersection to "beat the light." The fact that roundabouts may "feel" more dangerous to the average driver is a good thing: It increases vigilance. It's unlikely the average driver killed or severely injured in a high-speed "T-bone" crash as they drove through a green light felt much risk. In addition, drivers must slow to enter a roundabout: Placing an obstacle in the center makes this not only a physical necessity but visually disrupts the speed-encouraging continuity of the street. Motorists also travel through a roundabout more slowly than they would a traditional intersection: Roundabouts are typically built using what's called "negative superelevation," meaning that water flows away from the center and also that the road slopes against the direction of a driver's turn. As a result, any crashes in a roundabout take place at lower speeds and are thus less likely to be fatal. While roundabouts can be more costly to install than other kinds of traffic controls, such calculations don't take into account the fact that reducing fatal crashes also reduces social and monetary costs.
As Vanderbilt goes on to argue, roundabouts are also more energy- and time-efficient, and are better uses of public space.

So, when I hear that the City of Olympia is installing traffic circles in more locations...
Work began Monday on the first of three planned roundabouts to improve traffic flow and safety on Boulevard Road.

Crews for the general contractor, KLB Construction Inc. of Mukilteo, will clear trees and brush before construction begins in earnest at the T intersection of Boulevard and Log Cabin roads in southeast Olympia, said Sheri Zimny, project manager for the city of Olympia.

Crews will build a two-lane roundabout – the first city-funded roundabout in east Olympia – that features sidewalks, bike lanes, landscaping and lighting. Water and sewer lines also will be upgraded, and other utility lines will be buried.

The new roundabout also will feature the most ambitious artwork to grace one of the intersection control devices in the community so far. It consists of a circle of 10 wooden columns, each 8 feet high and carved with Northwest themes. Seattle artist Steve Jensen has characterized the $70,000 work as a “contemporary Northwest Stonehenge.”
...I get excited. And you should, too.

No comments: