Friday, March 11, 2005

Building a safer roadway

Good inspiration for road planners in Singapore..

"Building a safer roadway." By Melody Hanatani/ CNC Staff WriterFriday, 25 February, 2005. Watertown Tab & Press, on

How can a road be safer for pedestrians, drivers and bicyclists? That was the issue addressed recently at a traffic-calming talk, where residents of Watertown, Belmont and surrounding towns came to hear how they can make their communities safer.

Cara Seiderman, transportation manager for the city of Cambridge, spoke to a crowd of residents from local communities about traffic calming - how to redesign roadways to slow down traffic and increase pedestrian safety.

Using a PowerPoint presentation consisting mainly of photos of streets and intersections from across the country, Seiderman illustrated how visual and physical enhancements to existing streets can reduce the speed of vehicles, which can then increase the flow of pedestrians by making it safer to cross the street.

"People speed because the road environment tells them to," Seiderman said. Visual enhancements, such as trees, do not decrease the actual width of the road but create the appearance of a narrower road. According to Seiderman, the safest streets are found to be only 24 to 30 feet wide.

Chicanes are also commonly used in traffic calming. They slow vehicles by creating deviations and breaking up roads that were originally designed to go straight. Chicanes can include alternating parking from one side to the other, or placing a small island on the street.

Another way of redesigning streets is to raise the intersection, which works like a speed bump. "We tend to raise intersections where there are a lot of pedestrians such as parks and schools," Seiderman said.

A popular way of reducing speed is a roundabout, which works similar to a rotary but is designed better and safer. "A rotary is a badly and wrongly designed roundabout," she said. "A roundabout controls traffic and a rotary does not."

Roundabouts, which are used at intersections with high accident rates, allow only one vehicle at a time and reduce the number of places where conflict may occur between two vehicles or between a vehicle and a pedestrian.

"The roundabout has to be designed to be tight so it can slow the car down," Seiderman said.

Tightening intersections is a common way of reducing speed and conflict between vehicles and pedestrians, she said. A tighter intersection means drivers will slow down when making a turn, which gives them a better chance of seeing a pedestrian about to cross.

Seiderman also cited economic and health benefits that come along with traffic calming. There is a correlation between the lack of pedestrian access and inactivity, which can lead to obesity, Seiderman said. Showing a graph illustrating the trend in obesity and lack of walking, Seiderman said the group affected most is children.

When the audience of mainly adults was asked whether they walked to school during their childhood, a majority raised their hands. When asked whether their children walk to school, the number of hands was reduced to about two or three.

"People will walk, and some don't have a choice because they don't have a car," Seiderman said. "Studies show that more and more Americans are favoring sidewalks."
Better-designed streets also affect economic health positively by increasing the number of pedestrians along business districts.

To illustrate the business benefits of well-designed streets, Seiderman showed a photo of a woman riding a bike who stopped to smell flowers displayed on a storefront in Denmark. Seiderman said the woman went into the store to buy the flowers after smelling them. But what was interesting, she said, is that the woman already had bought some flowers at another store. "This could only happen if you're walking or cycling," she said.

Seiderman is a well-known expert on traffic calming and serves on the Massachusetts Governor's Highway Design Manual Task Force along with other traffic-related committees. A graduate of Harvard and the University of California at Berkeley, Seiderman received her degrees in urban planning.

The talk was co-sponsored by the East End Neighbors, the Watertown Bicycle Committee, Watertown Citizens for Environmental Safety, Belmont Citizens Forum, and various transportation committees from Lexington, Waltham, Arlington and Belmont.

"It's poor design that creates traffic," Seiderman said. "Pedestrians always have the right of way and many designs don't give that message. If you design something right, people will use it right."

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