Traffic congestion worsened in urban areas across America in 2005, costing motorists about $78 billion, or $5 billion more than in 2004, a new study finds.

The news could put more pressure on auto makers battling proposals for strict fuel-economy standards.

The study by the Texas Transportation Institute says Americans spent a 4.2 billion hours stuck in traffic in 2005, equivalent to a week of downtime for every commuter. That caused drivers to buy an extra 2.9 billion gallons (10.9 billion L) of fuel.

Compared with 2004, motorists in 2005 spent 220 million more hours going nowhere and using an additional 140 million gallons (529 million L) of fuel to get there.

To boil it down further, traffic congestion cost the average motorist in 2005 about $710, compared with an inflation-adjusted $260 in 1982.

Motorists in Los Angeles experienced the greatest gridlock, losing on average about 72 hours and 57 gallons (215 L) of fuel over the course of a year.

San Francisco, Oakland and Washington followed, with 60 lost hours and 47 gallons (177 L) and 43 gallons (162 L) of wasted fuel, respectively. Buffalo motorists commuted with the greatest ease, losing only 11 hours and 7 gallons (26 L) of fuel on average in 2005.

More importantly to auto makers, the findings arrive as the industry fights an increase in corporate average fuel economy standards recently passed by the Senate that calls for cars and trucks to reach a combined average of 35 mpg (6.7 L/100 km) by 2020 – a 40% improvement over current standards.

The industry favors a House bill that keeps cars and trucks separate. That proposal, which won the backing of 163 lawmakers earlier this month to kill a stricter rival bill, would raise the standard on cars to 35 mpg and bump trucks up to at least 32 mpg (7.4 L/100 km) by 2022.

A pitched debate between the two proposals looms in the coming weeks, when longtime auto industry ally U.S. Rep. John Dingell (D-MI) addresses the topic as part of global-warming legislation.

While the Texas study offers congestion solutions via a number of strategies – from car pools to more effectively using the Internet and telephone lines to tip motorists about potential backups – it also provides the ammunition lawmakers need to push auto makers into bringing fuel-efficient technologies to market sooner.

But the Senate’s measure also could cost consumers upwards of $7,000 per vehicle, the industry estimates.

Co-author Tim Lomax, a research engineer at the institute, stops short of calling the study an argument for stricter fuel-economy standards.

Indeed, he admits today’s engines are most efficient outside of stop-and-go traffic and warns that congestion will never disappear completely – even if governments were to successfully implement all the suggestions in the institute’s research.

At the same time, he adds, implementing those suggestions might lessen the burden auto makers carry.

“Getting public roads and public transportation to operate more efficiently will improve fuel economy,” he tells Ward’s, adding that reducing congestion also would trim greenhouse gas emissions and help lessen the country’s reliance on foreign oil.

Calls to Dingell’s Committee on Energy and Commerce for comment on the findings were not returned prior to deadline. The committee must formulate the congressman’s global-warming legislation.

However, General Motors Corp. believes alleviating traffic congestion is a key incremental step to reducing oil consumption. “We continue to be confronted by a complex issue, but finding a solution disproportionately falls on the auto industry,” a GM spokesman tells Ward’s.

“Reducing congestion is one thing that can be done. A vehicle sitting in traffic is getting zero miles to the gallon and just think of the emissions from all those vehicles in one place at the same time.”

As one solution to congestion, the study suggests trying to get more from infrastructure already in place, such as more low-cost programs that quickly remove damaged or stalled vehicles from the roadside and timing traffic lights for fewer stops and starts.

The nation could add more infrastructure capacity, the study suggests, although that doesn’t strictly mean building more roads. It could entail an extra rail line, more buses or an additional intermodal-transfer facility for freight and/or passengers.

Other solutions proposed by the study include relieving road and transit-system chokepoints, a decision that could prove somewhat costly if it means building a new freeway interchange, or relatively inexpensive if it means lengthening existing freeway entrance and exit ramps.

Motorists could alter their usage patterns by including doctor appointments or shopping trips to their workday commute. Governments could add different routes, travel modes or lanes that involve a toll for high-speed and reliable service, the study offers.

Additionally, the nation could change its development patterns so more people could walk to destinations.

However, the study reminds, some places, such as activity centers, always will witness heavy traffic at certain times of the day, and money would be more wisely spent addressing locations where the congestion problems are lengthier and less predictable.

Lomax says it’s difficult to place a price tag on trying to eliminate traffic congestion, partly because problems differ vastly from region to region. And some parts of the country are further ahead in alleviating congestion than others.

California, for instance, recently passed a new $19 billion-$20 billion bond package that attacks the problem by adding infrastructure capacity.

The state of Washington, meanwhile, has imposed two separate gas taxes of $0.09 and $0.10 in recent years. The state tells residents exactly how much money the tax generates each year and what projects it can afford to pursue, which makes bitterly high fuel prices easier for motorists to swallow, Lomax says.

But traffic congestion doesn’t just impact individuals, he warns. The cost it imposes on businesses, particularly vehicle manufacturers relying on just-in-time supplies, also is considerable. Therefore, efforts that help make lengthy back-ups more predictable would help.

“A manufacturer can handle an hour delay four out of five days of the week if they know it’s coming and they can plan for it,” Lomax says. “But throw in a 2- or 3-hour delay one of those days and it makes your operation less efficient.”

jamend@wardsauto.com