Go figure.

Driving is down this summer over the previous one in Southwest Riverside County.

But the traffic volume on North San Diego County freeways is up slightly, though the number of cars on the road hasn't fully rebounded to the levels of two years ago.

At the same time, the number of people taking public transportation is down in North San Diego County, but up in Southwest Riverside County.

Transportation analysts say the conflicting trends are the result of a combination of factors, such as the deeper economic downturn in Riverside County, the continuing attraction of San Diego-area tourist hot spots, the cost of gasoline being down $1.60 a gallon from this time last year and a state financial crisis that is pinching transit budgets.

It is hardly surprising that driving is down in Riverside County, analysts say, given that it has been hard hit by an avalanche of foreclosures and possesses one of the nation's worst unemployment rates at 13 percent.

"We generally see a decrease when we have issues with petroleum and problems with the economy," said Shelli Lombardo, a spokeswoman for the California Department of Transportation, or Caltrans, in San Bernardino.

Marney Cox, chief economist for the San Diego Association of Governments, a regional planning agency, said it is surprising that driving has increased slightly in San Diego County. While not as bad, the unemployment there has ballooned to 9 percent from 5 percent.

"I'm a little surprised that the increase in unemployment didn't offset completely any increase in people driving," Cox said.

Marie Montgomery, a spokeswoman for the Automobile Club of Southern California in Costa Mesa, said traffic may be up because more people from all over Southern California are choosing to stay close to home, rather than vacation out of state or overseas. And she said many are taking trips to San Diego County.

"They are doing staycations," Lombardo said.

Indeed, a survey taken for the club's annual Fourth of July travel trend report found that San Diego County is the No. 1 destination for Southern California travelers this holiday weekend.

"A lot of people are coming from L.A. and going through North County to Legoland and SeaWorld," Montgomery said.

More capacity

Whatever the reason, traffic on Interstates 5 and 15 and Highway 78 in North San Diego County was up 2 to 4 percent over June 2008, according to a database called the Freeway Performance Measurement System compiled by UC Berkeley researchers and Caltrans. The data is collected from sensors in the road and measures the number of cars passing a specific point within a given hour or day. Traffic volume is reported for multiple locations along major freeways.

That year-over-year increase followed declines ranging, for the most part, from 4 to 6 percent from June 2007 to June 2008 that transportation officials said were largely driven by skyrocketing gas prices.

Highway 78 between Rancho Santa Fe Road and Las Posas Road illustrates the trend.

Edward Cartagena, a spokesman for Caltrans in San Diego, said the daily volume there fell from 134,600 in 2007 to 131,800 last summer, and has since rebounded to 132,800.

A few places bucked the trend.

For example, traffic volume on southbound Interstate 15 at Pomerado Road was up by 22 percent year over year in June, following a steep decline of 14 percent a year earlier, database figures show.

Gary Gallegos, SANDAG's executive director, said the robust rebound there is likely the result of the four new express lanes available to commuters on I-15 through Rancho Bernardo.

A couple of years ago, many avoided the freeway because of the construction project, and now they are returning, Gallegos said. And they are being joined by motorists who used to take other routes.

"There is a lot more capacity on that road right now," he said. "We've made improvements, and those improvements have been loosening up the bottlenecks."

And speeds are up, Gallegos said.

But in Riverside County, the trend is still downward.

"In Temecula and Murrieta, we have seen a decrease of 5 percent in the volume of the traffic on I-15 this summer so far," Lombardo said. "And, then, on I-215 we have seen a decrease of 8 percent in the volume of the traffic."

For example, the number of cars on I-215 at Murrieta Hot Springs Road is averaging 76,300 per day this summer, down from 83,000, she said.

On I-15 at Murrieta Hot Springs, the volume has come down from 186,000 cars per day in summer 2008 to 176,700.

The downward trend is particularly pronounced in the services provided by the North County Transit District.

Fueled largely by widespread frustration with gasoline prices that flirted with the $5 mark, ridership on Coaster trains and Breeze buses soared to new heights in summer 2008. But the numbers came crashing down to earth within weeks of the stock market crash last fall.

"We had an increase last October, and ever since we've had falling numbers," said Tom Kelleher, a spokesman for the transit district in Oceanside. "I think it's just a reflection of what is happening in the marketplace."

More expensive

Figures weren't available for June. But Coaster ridership was down 27 percent year over year in May and 22.4 percent in April, district figures show.

The number of riders on North County buses declined 15 percent year over year in both those months.

Numbers were down less for the new Sprinter train: 3 percent in April and 6.3 percent in May.

Kelleher said the bus decline is likely the result of the district having to cancel some routes in the face of state funding reductions.

He said the train decline may be the result of a $40 charge for a monthly pass instituted last fall for train passengers transferring to buses that shuttle them to Sorrento Valley offices. Those shuttle rides used to be free and one-third of Coaster passengers get off in that area.

That new charge was in addition to two sets of fare increases -- in July 2008 and January.

In Riverside County, the Riverside Transit Agency has been encountering little resistance.

Agency spokesman Brad Weaver said by e-mail that bus ridership had increased by 13.4 percent year over year through the first 11 months of the fiscal year that just ended last week.

And Weaver said ridership on CommuterLink express routes was up 32 percent.

"So why the increase? High gas prices last summer may have driven some of our customers to ride the bus for the first time, and many of them are staying on board, happy with the service we provide and not wanting to go back to driving," Weaver said. "We are also experiencing a strong demand from commuters who are taking advantage of our express service."

That service expanded last week with the introduction of two new express routes, including Route 217, which connects Temecula and Hemet with Escondido.

Call staff writer Dave Downey at 760-745-6611, ext. 2623.