SAN DIEGO -- Soaring construction costs already are threatening the completion of San Diego County's $14 billion, 40-year road-building program one year before it starts receiving cash from a countywide sales tax, transportation officials say.

Since 2002, construction costs have nearly doubled and they are rising three times as fast as sales tax revenues, said Richard Chavez, principal transportation engineer for the San Diego Association of Governments, a regional planning agency, last week.

Jack Boda, the association's director of mobility management, said in the same interview that the escalation reflects fast-rising prices worldwide for steel, asphalt and cement -- the main building blocks of freeways, railroads and bridges.

"It has our attention," Boda said.

At the same time, spiking costs have leveled off before and should do so again, he said.

The road-building program will be paid for with money from TransNet, the name the agency has attached to a half-penny on the dollar sales tax that San Diego County voters originally approved two decades ago for a diverse menu of transportation projects.

That tax went into effect April 1, 1988, and was due to expire one year from today. But voters, in the November 2004 presidential election, gave the association permission to continue collecting the special tax for another four decades.

Most North County residents pay 7.75 cents in tax for every dollar they spend at retail stores. Those who make purchases in Vista, however, will begin paying 8.25 cents today.

With the $14 billion anticipated to come from 40 more years of sales tax collections, the agency proposes to widen Highway 76 to four lanes between Oceanside and Interstate 15, to extend the I-15 express lanes north to Highway 78 in Escondido, to widen Highway 78 to eight lanes between Oceanside and Escondido and to build car-pool lanes on Interstate 5 through North County, among other big projects.

However, with construction costs on a pace to double every four years, there is a danger that buying power will be eroded and that some projects won't be completed on time, if at all, officials said.

Left behind

If a project or two gets left behind, it won't be the first time.

During the inaugural TransNet, money ran out before the agency could follow through on 1988 promises to complete Highway 76, extend Highway 52 to Highway 67 in Santee, and build a $1 billion San Diego Trolley extension in the La Jolla area within the first two decades.

But those projects won't be left behind again, officials said. That's because they were given special priority in the second TransNet measure. The projects are part of something called the TransNet "Early Action Program" and are first in line for the sales tax dollars. Agency spokesman Garry Bonelli said each of them will remain on schedule and be completed by 2015.

"We'll definitely still be able to deliver everything we have in the lock box -- the 76, the 52 over to 67 and the midcoast Trolley from the Old Town transit station up through the campus of UCSD and over to University Towne Centre," Bonelli said.

But projects set to get built in later years could be in jeopardy if cost trends continue.

"The question is, what are we going to be building in 2030?" Bonelli said.

Or, some planned bus routes might end up running every 15 or 20 minutes rather than every 10, he said.

As for the I-5 widening, it is scheduled to be built during the early years of the measure. Environmental studies are expected to be completed by 2009, and construction is expected to wind up around 2016, according to the California Department of Transportation office in San Diego.

Consequently, association officials say, the $2.4 billion project is not likely to become a casualty of soaring costs.

Construction costs are soaring for several reasons.

China's booming economy is one, as that giant country rushes to build dams, highways, railroads and Olympic stadiums that are boosting worldwide demand for steel, cement and asphalt, Boda said.

"China has been building like crazy," he said.

Then there are the soaring global oil prices that factor heavily into the cost of asphalt, he said. And closer to home, Boda said, the multibillion-dollar replacement of a San Francisco-Oakland Bay Bridge span damaged in the 1989 Loma Prieta earthquake has strained steel supplies.

The recent housing boom also has -- in California and across the nation -- made cement more scarce and triggered a salary-escalating competition for skilled construction workers, he said.

And the pressure to rebuild quickly in hurricane-ravaged communities of Louisiana and Mississippi hasn't helped matters, Bonelli said.

Light at the end of the tunnel

Chavez, the engineer, said all those factors have translated into fewer bids being submitted for highway projects and have resulted in higher than usual bids.

For example, Chavez said, in 2002 road-building agencies were entertaining six or seven bids for every job they advertised. But by 2005, that number had dwindled to three or four. On the positive side, he said, the number is beginning to creep back up, probably because of the slowdown in home construction.

"There is light at the end of the tunnel," Boda said. "One good thing about our future projects is that most of them don't require a lot of right-of-way purchases. So we don't have to control the real estate market."

And, Boda said, "What goes up should come down. There should be some leveling off over the 40-year period that can help make this program work."

After all, he said, the region has seen this kind of thing before.

Indeed, said Chavez, construction costs also spiked during the high-inflation, energy-crisis of the 1970s. Costs tripled between 1972 and 1980.

But stable prices persisted during the 1980s and 1990s, Chavez said. In fact, during the recession of the early 1990s, sales tax receipts actually were increasing faster than construction costs, he said.

While agency officials are not advocating a return to recession, they are hoping for a return to a trend of more gradual increases.

In the meantime, Boda said, the agency must do all it can to keep project prices from spiraling out of control. While it can't control what suppliers charge for materials, it can resist the temptation to add project features that might seem appropriate but were not promised in the 2004 TransNet ballot measure, he said.

"We have to stick with what we committed to the voters," Boda said.

Contact staff writer Dave Downey at (760) 740-5442 or ddowney@nctimes.com.