City Experiments with Radar Feedback Signs

Somerville has been experimenting with radar feedback signs to see if they slow down traffic on streets where they're placed.

The signs, which are solar powered, monitor the speeds of passing cars and display those speeds to drivers using large numbers. If a driver surpasses the speed limit, the sign flashes his speed using red numbers.

The signs are supposed to serve three purposes. First, they record speeds, helping the city collect data about traffic where the signs are placed. Second, they alert drivers to how fast they're driving, letting them know when they're driving too fast. Third, they are intended to encourage drivers to slow down.

The speed limit in Somerville is 30 miles per hour. If you drive by a sign going 42, the sign will flash that number in giant red numbers. As a driver, you may think, "Wow, I was driving too fast; I should slow down." Or, you might think, "If that were a cop, I'd have a ticket right now."

"It's making people cognizant" of their speed, said Matt Dias, acting director of traffic and parking in Somerville. He said it's "a low cost way to keep [speed] on people's minds."

At the moment, the city is experimenting with two signs. They were placed in wards 5 and 2 in April, and now they're placed in wards 3 and 7, on Summer Street and Broadway respectively.

The city does not own the signs. Instead, it is using them as part of a trial period with the company that sells them, Signal Service, out of East Hartford, Conn. If successful, the city may purchase two or three of the signs, said Dias.

One of their benefits is their mobility. They can be moved from street to street, from neighborhood to neighborhood, to address speeding problems where they exist.

Dias said that from a pedestrian's perspective, even cars going the speed limit can seem to be driving dangerously fast. Overall, these radar feedback signs would become part of a broader effort to slow down traffic in Somerville and make the city more friendly for pedestrians and bikers.

However, the city is still working to determine if the signs are effective. "We kind of wanted to give them a dry run first," said Dias, referring to the current trial period for the signs.

It's possible the signs will work. It's possible drivers ignore them. During one experiment, the city turned off the display so that passing drivers couldn't see their speeds. However, the sign was still on, and it was still collecting speed data. The city wanted to see if the display made a difference in terms of slowing drivers down. It is still assessing the results.