Carroll County officials want to employ a road design pioneered in Mexico to ease traffic problems on Route 140

New anti-congestion plan sought

March 15, 2006|By LAURA MCCANDLISH | LAURA MCCANDLISH,SUN REPORTER

Exploring a new approach to an old problem, Carroll County officials want to ease congestion on Route 140 with an intersection design pioneered in Mexico that diverts left-turning motorists into a separate lane well before they reach a busy crossroads.

Yesterday, Carroll County and Westminster leaders sent a letter to state transportation officials endorsing their plan to implement the "continuous flow" intersection format at two crossroads on Route 140 in the county seat.

The design is in use at only two places in the country: Prince George's County and Long Island, N.Y., according to Michael Bruce, a transportation engineer with ABMB Engineers in Baton Rouge, La., where a third project is under way.

But Maryland transportation officials say they also plan to implement the design at other locations troubled by heavy traffic.

Advocates promote the concept as less expensive and less invasive than overpasses and ramps to solve congestion problems, though the need for land to accommodate wider roadways and the prospect of selling a new approach can be obstacles.

"They have a lot of advantages: Left-turning vehicles have their own lanes, congestion is reduced, and both the safety and inefficiency of the intersection is improved," said Charles Gischlar, a spokesman for the State Highway Administration.

Traffic on Route 140 has long been a problem for Carroll officials.

In the fall, the county commissioners scrapped a decades-old plan to build a bypass around Westminster, saying the county lacked the money for the project and could not build it without funding from the state.

The commissioners decided to shift their focus to improvements for Route 140, the main artery through the county seat.

Daily traffic volume along the highway is estimated at 50,000 vehicles, and state highway officials have projected that to grow to 70,000 within 20 years.

The letter sent to the state yesterday by county and Westminster officials expressed a desire to use the design at two Route 140 intersections: Englar Road and Center Street.

"When we wanted to put in roundabouts, people also thought they were nothing but confusion, that they would never work," said Commissioner Julia Walsh Gouge. " ... The costs should be less, but they should move a lot of traffic."

"We would be on the cutting edge," Gouge added about the proposed intersections.

Although about 50 such intersections have been built in Mexico in the past 10 years, Bruce said transportation engineers have been reluctant to try a technique that hasn't been widely tested in the United States.

"Transportation engineers are slow to innovate," he said. "When you are dealing with public funds, nobody wants to take a risk. People fear that if they fail, they'll be blamed. If a project is a success, there's not a lot of reward."

The idea of the design is to move the left-turn lane out of the main intersection by locating a left-turn "bay" with a traffic signal several hundred feet before the problem intersection.

The left-turn bay empties into the cross street near the main intersection.

Single controller

All the signals for the intersection are operated by a single controller and are intended to be coordinated to provide continuous traffic flow.

For example, drivers approaching the Route 140 and Center Street intersection would enter a left-turn lane and stop at a light. On the green light, the drivers would cross oncoming lanes, where traffic is stopped at a red light. Then, they would proceed up a lane, separated by a median strip to the left of the oncoming, Route 140 traffic. The left turn is completed onto Center Street, without having to stop.

"It's a new concept that's hard to describe but much easier to drive," said Erik Fisher, Westminster's assistant town planner. "Even though it involves two stages and two signal lights, you actually get through the turn faster."

In Prince George's

Carroll County officials have visited the Prince George's County location, which opened in 2002 at the intersection of Routes 210 and 228. They said were impressed with how smoothly traffic flowed.

"It doesn't feel a whole lot different than driving through a typical intersection," said Steven C. Horn, county planning director. "It's the way of the future."

A third problem intersection along Route 140 might be addressed with a more traditional approach. County officials said they want to consider a raised interchange at Routes 140 and 97 (Malcolm Drive), the only intersection of two state roads in the area that state officials say lacks a proper interchange with ramps and bridges.

Gouge said she expects that the county will establish a timeline for the construction of the intersection improvement with the State Highway Administration over the next few months.

"It won't happen overnight but this is a good start," Gouge said of the letter to the state.

laura.mccandlish@baltsun.com

For more information on continuous flow intersections and a computer-generated video of one in action, go to www.abmb.com/cfi-testdrive.html

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