More than 50 years ago, in 1957, the American Association of State Highway and Transportation Officials recognized the concept that widening highways to relieve congestion inevitably produces more congestion.

Economists call the phenomenon "induced demand." It's actually a very practical concept. If you have been avoiding a particular route due to congestion and the government widens that road, you and others might give it a try. That adds to the traffic flow and helps to rebuild the congestion that the project was meant to relieve. Once the expanded road becomes congested, the answer is ... expansion. And on and on it goes.

Construction cost is, perhaps, the sole factor restraining virtually endless construction.

Interstate 81, which stretches 856 miles from Northeast Tennessee to the Canadian border and is a main artery through the heart of northeast Pennsylvania, is very heavily congested in many areas. A stretch from just north of Scranton into Luzerne County is particularly congested because it marks the confluence of I-81 with Interstate 84, a major route into New England. PennDOT plans to add two lanes to I-81 from the Central Scranton Expressway into Luzerne County, at a projected cost of about $174 million.

Meanwhile, the I-81 Corridor Coalition, comprising transportation planners from the six states through with the interstate passes, plans to try innovative uses of technology to help relieve congestion.

Using less than $500,000 in federal transportation funds, the coalition plans to establish a system to provide truckers with real-time information about congestion, potential alternate routes around it, and even using rest time as congestion dissipates. Heavy trucks are about 21 percent of total traffic on I-81.

The participating states also should promote rail to reduce I-81's truck congestion.

Meanwhile, there is some hope for less congestion in that Americans have become a bit less car-crazy.

According to the University of Michigan's Transportation Research Institute, the ratio of cars to people is falling. Vehicle ratios per person, per licensed driver, and per household all peaked between 2001 and 2006, according to the institute. There were 0.79 vehicles per person in 2006 and 0.75 in 2011, the most recent year for which data are available. Vehicles per licensed driver hit 1.16 in 2001, but has declined to 1.1. And in 2011, the number of vehicles per household, 1.95, was at its lowest point since 1993, after being higher than two for 11 years.

Perhaps a flip side to induced demand - fewer cars, less congestion - finally will prevail.