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Timing is everything in the fuel-savings game: INDOT to synchronize signals in more area brake zones

May 8, 2006

State transportation engineers, having just tweaked traffic-light timing to improve flow on U.S. 31 in Carmel, next plan to target three other busy corridors in the metro area.

They include U.S. 31 on the south side, between Interstate 465 and County Road 750N, and the increasingly congested stretch of State Road 37 between State Road 238 and Cumberland Road in Noblesville.

The improvements to be conducted over the next several months can't come fast enough for motorists weary of the red-light-to-red-light waltz.

Idling wastes gasoline, which is flirting with $3 a gallon.

"Any improvements along those lines would certainly be helpful. Some areas are worse than others," said Gene Norman, manager of Indy Express, an Indianapolis company that delivers timesensitive packages.

On this day, Norman had a driver just come back from the Fishers-Noblesville area. "I noticed he was a little bit late. He just said, 'traffic problems.'"

State officials are trying to improve safety in areas with stop-and-go problems that warp brake rotors or worse.

"We're trying to make sure that we reduce the possibility of rear-end collisions from stopping and starting," said Indiana Department of Transportation spokesman Will Wingfield.

Generally, the timing of traffic lights, particularly in complex intersections with left-turn arrows, is determined by computer modeling. Lately, engineers are looking at intersections firsthand, "which means we get in a car and drive the route a couple of times," Wingfield said.

"The overall concept is actually very complex."

One of the problems they observed last month when resetting traffic signals on U.S. 31 in Carmel was how southbound vehicles tended to back up waiting to turn left while commuting to businesses on 96th Street.

During busy morning hours, INDOT increased the frequency of left-turn arrows, activating them before and after green lights for northbound through traffic on U.S. 31.

During other times, the left turn arrow onto 96th Street occurs just once per cycle.

It's not a perfect science, and INDOT acknowledges the U.S. 31 and 96th Street changes will offer only "small to moderate" improvements during peak hours, with most of the benefits coming at less-busy times.

Meanwhile, INDOT plans a third traffic signal synchronization project this year on U.S. 40 in Plainfield, from Moon Road to Bridgeport Road.

INDOT is aiming to achieve at least a 15-percent travel-time savings in its project areas.

The National Transportation Operations Coalition, a group sponsored by the Federal Highway Administration, said capital investments to upgrade signals nationwide could result in a 10-percent reduction in fuel consumption-or nearly 17 billion gallons nationwide.

The group also said a concerted effort to improve the nation's signal system could reduce traffic delays 15 percent to 40 percent, slash travel time as much as 25 percent, and reduce stop time up to 40 percent. That pans out to a savings of 50 hours per year for the person who spends two hours in the car commuting per day.

The coalition also projects a reduction in emissions such as carbon monoxide and volatile organic compounds of up to 22 percent.

But the improvements would not come without a cost. NTOC estimates that government entities would have to spend upwards of $265 million a year.

That would represent a lot of new spending. Government entities often don't make changes to traffic light systems but every three to five years, according to the group. And they often don't bother to coordinate with neighboring jurisdictions, which can cause traffic tieups as motorists cross from town to town.

The city of Indianapolis on a "fairly regular basis" takes a look at signal timing, particular in the city's busiest intersections, said Indianapolis Department of Public Works spokeswoman Margie Smith-Simmons. Officials could not immediately say whether any particular areas were under additional scrutiny as gas prices soar.

Using federal funds designated for emission reductions, the city recently added electronics and vehicle detection loops along Michigan and New York streets, from Pine Street to Emerson Avenue.

"Prior to this project, the signals were pre-timed and, even driving the posted speed limit, cars would get stopped at some side street where no cars were waiting to proceed through the intersection," Smith-Simmons said.

The city also has made improvements along Keystone Avenue/Rural Street, from Brookside Parkway to Woodfield Crossing.

According to U.S. Census data, Hoosiers spend an average 21 minutes commuting one-way and Indiana ranks 35th in the nation for average commute time.

That's little consolation for commuters crawling in bumper-to-bumper logjams in notorious stretches such as Interstate 69 in the Fishers area. INDOT said the solution in many of those cases is to widen ramps. It plans to start work soon to widen the southbound ramp at the I-69 and 116th Street interchange. The shoulder of northbound lanes of I-69 at 116th Street, which back up during the evening drive home, recently sprouted surveyor's flags for possible widening.
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