December 20, 1999 Web posted at: 10:03 a.m. EST (1503 GMT) by Rebecca Sykes

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BOSTON (IDG) -- Barring disasters, few cities are ever handed new open space right downtown, but Boston will gain 27 open acres when its elevated highways are relocated underground in a project informally known as the Big Dig.

In the roadways below that open acreage, the Big Dig will embed around $250 million worth of technology, including 30,000 data acquisition points, from sensors to video cameras, to help smooth and soothe Boston's notorious traffic.

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Providing motorists with up-to-date information is one crucial component of the new roadways, according to Sergiu Luchian, Intelligent Transportation Systems (ITS) manager at the Massachusetts Turnpike Authority, which is responsible for the Central Artery/Tunnel project, aka the Big Dig.

Many tunnels are longer than Boston's new tunnel, but they go straight through the mountain or other obstacle they were built to circumvent and do not have decision points -- exits and entrances -- at which the motorist must make directional choices, Luchian said.

Three major interchanges will be underground in Boston, and motorists must figure out which way to go as they drive by at highway speeds, surrounded by tile and deprived of buildings and other landmarks with which to orient themselves, Luchian said.

"Most tunnels in the world look like very long bathrooms," he said.

Motorists need precise directional information in order to choose the right route, and the new roadways will be salted with 120 variable message signs to help motorists navigate, according to Luchian.

These temporary message signs are familiar to many as the lighted roadside signs, often askew, which warn drivers of "grooved pavement ahead" on roadways under construction or of a "road closed" during a special event.

The new signs will be permanent parts of the roadway, though their message will be changeable. For example, a sign may display boxes with green checks to indicate which lanes are open and red "x"s to indicate that a lane is closed, Luchian said. The signs will be controlled by workers at the Operations Control Center, nearby.

Technology will also help minimize the time disabled vehicles block traffic. Especially in a tunnel, swift removal of disabled vehicles is crucial, since there is no where else for the traffic to go.

"Somebody with a very prosaic flat tire can bring traffic to a grinding halt for an extended period of time," said Kenneth Orski, an ITS consultant.

Some parts of the new roadway snaking underneath Boston's downtown have breakdown lanes, but in many places the roadway is flush up against building foundations and other subterranean structures; there simply is no room for breakdown lanes, according to Luchian.

"We're within inches of almost every building along the corridor," Luchian said.

New sensors and video cameras will help quickly whisk disabled vehicles out of the way, according to Ray Pardo, manager of systems integration for the Big Dig. Every 200 feet within the tunnels are sensors which track traffic volume and speed. If there is a discrepancy between two sensors -- if cars are going 10 miles per hour past one sensor and 40 miles per hour past the next sensor -- the computer knows that an obstruction is likely between those two sensor points and sounds a tone to alert workers at the Operations Control Center.

Within two minutes of a traffic discrepancy, operators should have heard a tone and be aware of the problem, according to Pardo. A further two minutes will be spent verifying it, as they turn video cameras in the direction of the perceived difficulty. Within eight minutes, a repair truck will be on the move toward the disabled vehicle, with the goal of pushing the vehicle out of the way of traffic within 15 minutes of its disablement, Pardo said. The goal is ambitious but important, because according to traffic studies, every 15 minutes a broken-down car blocks traffic translates into one hour of congestion, he said.

And that's congestion on both sides of the roadway, since people driving in the other direction typically slow down to look. "We have all seen how an accident can affect traffic flow -- not only because it blocks a lane but also because of the so-called 'gape factor,'" Orski said. "One of the early payoffs of ITS technology is improved incident clearance capability."

Another payoff concerns fires. Although tankers carrying flammable liquids are not permitted in tunnels in Massachusetts, car fires or fires from other transported goods can certainly happen. The tunnel fans that are used for routine ventilation can be used to get smoke -- the immediate hazard -- out of the tunnel, according to Pardo.

"You've got to try to get that smoke out very quickly," Pardo said.

Big Dig officials know something about smoke. They located a tunnel in West Virginia that was boarded up when the roadway which travelled through it was rerouted, Pardo said. Officials deliberately set a series of 100 fires in the tunnel to study smoke patterns and other tunnel-fire behavior, and can use the information learned to minimize the affect of fire in Boston's tunnels, according to Pardo. For example, the fans can drag the smoke in different directions, depending on what makes sense, and help starve the fire, he said.

The Operations Control Center monitoring the systems will be online soon. When designing the center in 1990, planners allotted a large room for the two supercomputers, which they envisioned would power the roadway monitoring systems. Ten years later, that room is solely occupied by a small computer cabinet and two Compaq Computer desktops running OpenVMS on an Alpha processor. Only one PC is needed to do the job; the other is a back-up, Luchian said.

"We thought we were going to have two Crays," Luchian said with a smile.