July 21, 2008

Fuel costs, economy contribute to decline in traffic volume

By Steve Schmidt
UNION-TRIBUNE STAFF WRITER

But the run-up in gas prices has helped put San Diego County in reverse. In what experts say is the first documented decline of its kind, freeway traffic is down.

A San Diego Union-Tribune analysis of state data shows a sizable decline in traffic volumes at several highway bottlenecks in the region.

“Gas prices have certainly within the last two or three months altered the transportation patterns of a lot of people,” said Pedro Orso-Delgado, local Caltrans director.

At certain points on the freeways, including on Interstates 15, 805 and 8, weekday traffic in June declined by as much as 9.1 percent and by at least 3.3 percent, compared with the same time last year.

Weekend trips thinned out even more, with decreases ranging from 5.2 percent to 11.9 percent.

The figures were calculated using Caltrans data drawn from traffic sensors embedded in the roads.

To many drivers, the difference goes beyond the lighter freeway traffic that is standard in the summer.

“I've really seen a change in the last few months,” said Julie Dooley of Mira Mesa, who commutes to her office job in downtown San Diego four days a week. “It doesn't seem as bad as usual.”

Regional averages also reflect a decline in traffic volume, according to Berkeley Transportation Systems Inc., a San Francisco Bay Area firm that manages traffic data for Caltrans. It found that weekday traffic in San Diego County overall slipped 3.8 percent during the second week of this month when compared with the same time period last year. Weekend volume slid 5.2 percent.

Orange County, Sacramento and the Bay Area also saw decreases, especially on Saturdays and Sundays.

“One conclusion you might draw is that people are choosing to take fewer discretionary trips,” said Karl Petty, chief executive officer of the Berkeley firm.

The figures are the latest sign that high gas prices, along with the state's growing economic slowdown, are driving Californians out of their cars.

Local transportation officials recently reported a faster-than-usual rise in bus, trolley and commuter-train ridership.

The number of people who rode the San Diego Trolley grew 6.8 percent, to a record 37.5 million passengers, between July 2007 and last month. Ridership in government-subsidized van pools that take employees to work is at a record level in the region.

Transportation experts and economists have been tracking gas prices with great interest, wondering when high fuel costs might spur commuters to seek alternatives to the car.

Some say we are reaching that point.

Marney Cox, an economist with the San Diego Association of Governments, said motorists are bracing for lasting changes in the economy and energy costs.

He said they are buying hybrid vehicles, shifting to public transportation or limiting their trips.

“Instead of thinking these changes are temporary, they are thinking they are permanent. And that's unique,” Cox said. “I think for the first time that I can remember people are making decisions about their long-term transportation choices.”

Alex Skabardonis, research engineer with the Institute of Transportation Studies at the University of California Berkeley, was reluctant to draw conclusions about the drop in traffic volumes, but was intrigued by the trend.

“It's a very interesting thing because for a long time it was thought that changes in gas prices didn't cause much change in traffic,” Skabardonis said.

Commuter Raquel Herrera of Leucadia said her habits have evolved. Instead of driving five days a week to a clerical job near Old Town, she rides the Coaster commuter train twice a week.

“It's working out OK,” Herrera said. “Sometimes it's still easier to take the car, but I just hate paying those gas prices.”

Experts said the decline in traffic volume goes beyond the price at the pump, saying the faltering economy is also a factor. They note that traffic volume in California has dropped during other periods of economic uncertainty and rising fuel prices.

As the local economy has declined, Caltrans has completed construction projects in the region, including adding lanes on several freeways and widening the Interstate 5/805 merge.

The projects have significantly improved the flow of traffic, and in good economic times, such work generally would be expected to increase traffic volume.

These days, however, traffic is thinning. Here are some comparisons between June 2008 and June 2007:

 Westbound state Route 78 in Vista, down 9.1 percent on weekdays to an average of 1.19 million vehicles in June 2008, and down 9.7 percent to 390,000 vehicles on weekends. The Sprinter light-rail line opened parallel to Route 78 this year.

 Westbound I-8 at Waring Road. About 2.37 million vehicles traveled the freeway on weekdays in June 2007 versus more than 2.26 million last month, a 4.6 percent drop. Weekend traffic slid 6 percent, to 683,000 vehicles.

 Northbound I-805 at Orange Avenue and Olympic Parkway in Chula Vista, down 7.9 percent on weekdays to 1.25 million vehicles in June, and 11.9 percent on weekends to 415,000 vehicles that month. Caltrans officials attribute much of the decrease to the opening of state Route 125, a toll road in South Bay.

 Southbound I-5 at Del Mar Heights Road, a 17.6 percent weekday decrease to 1.99 million vehicles and a 15.3 percent drop to 715,000 vehicles on weekends. Caltrans opened a carpool lane in the area late last year. Agency officials said the unusually large decrease at Del Mar Heights Road may be partially linked to the apparent failure to count cars in the new lane.

Caltrans maintains 600 vehicle detection stations in the region, each a collection of sensors embedded in the roadway.

The Union-Tribune was unable to analyze some stations in the state's traffic database because of incomplete data or inoperable sensors. Those stations included often-congested spots on Interstate 5 such as Via de la Valle in Del Mar, Lomas Santa Fe Drive in Solana Beach and near the U.S.-Mexico border.

State officials and university researchers created the database in 1999 to track and analyze traffic patterns.

Several experts say traffic has thinned during previous energy and economic trials in California, but they've never seen a documented decline on this scale.

“My thought is that's all about gas,” said Petty, the Berkeley Transportation Systems CEO.

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Steve Schmidt: (619) 293-1380; steve.schmidt@uniontrib.com