Do New Highway Lanes Equal Less Traffic?

As with many busy roadways across the country, there are times when traveling on the New Jersey Turnpike becomes a nightmare. Traffic, traffic -- and then more traffic -- tends to put a damper on any plans awaiting drivers once they reach their destinations.

The problem stems from a merge of car-only lanes with car-truck lanes, which backs up a 20-mile stretch that 120,000 drivers in both directions use each day. Engineers consulting with the state's turnpike authority have determined that one area has experienced "failure traffic levels" during morning and evening rush hours, and the conditions are expected to worsen to failure levels across the entire 20-mile span by 2011.

"Anyone who has traveled the turnpike through the middle of New Jersey knows this treacherous merge," said acting Gov. Richard J. Codey in announcing plans to extend the separation of lanes throughout the congested area. "It is one of the worst traffic spots in the state."

Codey said the $1.3 billion expansion project -- announced in December and still in the engineering and design stages -- is crucial for the region's commuters. "If we don't act, over the next several years, traffic growth in New Jersey, combined with a planned project in Pennsylvania to add a full-access interchange between the Pennsylvania Turnpike and the New Jersey Turnpike, will cause virtual gridlock," he said in a statement.

Ultimately, however, the area may face the same difficulties, according to several transportation experts. When highways reach traffic capacity, the answer can seem obvious -- more lanes equals more space for cars to travel, solving the problem.

The reality is that congestion is alleviated, but only temporarily. Then more people hear how great the new road is, try it out and voila! -- again there's bumper-to-bumper traffic.

The Dreaded 'Triple Convergence'

Widening roadways might solve the problem if the new lanes were only used by existing drivers, said Anthony Downs, a senior fellow at the Brookings Institution who has written several books about traffic, including "Still Stuck in Traffic."

But the dreaded phenomenon Downs calls "triple convergence" comes into play: People who previously traveled other routes, at other times and by other modes, converge onto the new, widened expressway until it's just as crowded as it was before.

"If you widen and that happens, more people are traveling on it, but it does not eliminate congestion," he said.

So why bother adding lanes? "You have to analyze the circumstances," Downs said. "If the goal is to increase the capacity of a system so more people can move on it at rush hour, it may make sense to expand. If the goal is release, I don't think congestion can be eliminated. I think congestion is an inescapable part of living in a modern [era.]"

Indeed, the problem is here to stay, and it promises to get worse. According to the 2004 Urban Mobility Report, a study by the Texas Transportation Institute released in September, each year American cities are falling further behind in the battle against traffic congestion.

The study looked at 20-year trends in traffic congestion and focused on 85 urban areas with populations greater than 500,000. It found that congestion has grown in areas of every size, and it lasts for a longer period of time. The average annual delay for every person using motorized travel during peak periods in the areas studied climbed from 16 hours in 1982 to 46 hours in 2002.

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