Commuters on the Parkway West might have noticed a bit of new information during their morning drive -- an estimated travel time to the Fort Pitt Tunnels from Parkway Center, displayed on an overhead message sign.
By itself, that isn't of much value -- by then, a driver has no choice but to descend to either the tunnels or the nearby exits. But it's the first taste of a system that the Pennsylvania Department of Transportation hopes to expand, to help drivers avoid trouble.
Estimated travel times currently are displayed to outbound Parkway East travelers from the Allegheny County Jail to the Squirrel Hill Tunnels. Those messages began in May 2011.
Ben DeVore, manager of PennDOT's Western Regional Traffic Management Center, said he could not estimate when more travel time information would be provided on the Parkway West or inbound Parkway East.
Rigorous testing is needed to ensure the accuracy of the information that is provided by microwave detectors placed at half-mile intervals along the parkways. The detectors measure traffic speeds every minute or so and use the information to compute the expected travel time.
PennDOT workers drive the routes repeatedly to compare the actual travel times with what the sensors are estimating, Mr. DeVore said. After two months of such testing on the inbound Parkway East from Penn Hills to the tunnels, "I'm still not comfortable with the numbers I'm getting," he said.
"The Parkway West we tested for a solid six months. We try to be very, very accurate," he said, with a goal of being within two minutes of the actual travel time, 85 percent of the time. "We don't want to put bad information out there."
The message signs that will display travel times also are used to advise motorists of crashes and traffic congestion.
They fall under the umbrella of what engineers call "intelligent transportation systems," which includes variable digital message signs, traffic cameras and speed sensors.
The travel-time messages are expanding throughout Western Pennsylvania. Washington County is preparing to debut a network of 21 cameras and eight message signs later this year, said PennDOT spokeswoman Valerie Petersen. Work also is underway on a network on the highway system north of Pittsburgh, all the way to Erie.
"We can't build ourselves out of congestion," Mr. DeVore said. "The idea is to present travelers with as much information as possible so they can make informed decisions about what is the best route to their destinations."
Projects that are under construction now or in the near future will bring the number of digital message boards in Western Pennsylvania to 100, he said. PennDOT has 182 traffic cameras in the region, a number soon to grow to 225.
In addition to the east and west parkways, PennDOT has begun testing to provide travel time estimates on the Parkway North.
The information would be displayed at Union Avenue, a common congestion point during the morning rush.
For now, drivers can view real-time traffic camera images, average highway speeds and other traffic information on the 511pa.com website, which also is accessible to smartphones and other mobile devices.