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Transportation really matters about now. It’s road trip season, after all. Summer vacation beckons. Sports utility vehicles throughout San Diego are tuned, oiled and gassed. Ready to hit the road.
So what kind of road do they hit? From asphalt pavement to concrete interstates, roadways have come a long way from the days when a one-lane plank road (as in wooden planks) transversed the Imperial Valley. The main east-west road into San Diego County around 1920 made a summer-vacation road trip a more arduous affair.
Until a few years ago, a section of this plank road was on display at the California Department of Transportation office in Old Town, a neighborhood that, of course, has its own redoubtable place in local road lore. Long before the days of the plank road, Old Town was infamous for its so-called streets — dusty, dirty and flea-ridden in the summertime and worse in the winter when the roadway aggregate was running mud and any slurry seal came from the horses.
Today the streets are paved with asphalt and concrete, and Caltrans is engaged in a 10-year plan to rehabilitate and preserve California's road system, reports Leo Mahserelli, district project management engineer for Caltrans District 11, which encompasses San Diego and Imperial counties.
So is there more asphalt or concrete under our vehicles' wheels? "In terms of lane-mile, they're about 50-50," Mahserelli says. "It looks like there's more asphalt, but there's really not because the concrete roads (freeways and the like) have so many lanes." He says there are 3,900 lane-miles in District 11.
Concrete is the more expensive choice to lay down initially, but it requires less maintenance over its life span. Asphalt needs much more sealing over time. The common enemy of both is water.
"That's what’s detrimental to asphalt and concrete," says Mahserelli. "Even out in the desert, they're very aggressive about putting down a seal coat within a year (of new pavement being laid) because it starts to oxidize."
On city streets, asphalt gets a slurry seal (a thin blanket overlay of fresh oil and asphalt) every so often to keep the pavement fresh and to keep the water out. If the asphalt on San Diego’s mountain and desert roads seems like a rougher ride, it’s because the roads less traveled get a chip seal, a thicker mixture of an oil binder with fine rock.
The rounds of sealing pay off. "There's a 10-year design for the asphalt for rehabilitation, but we get more out of it with the preventive maintenance," Mahserelli notes.
Yet below every good road of asphalt or concrete your vehicle is riding on an aggregate base (a specified mix of sand and refined rocks no bigger than 3/4 of an inch), and below that a sub-base of sandy decomposed gravel, and often another permeable base layer designed to carry off roads' main enemy, water. Road design and construction, of course, even encompass the soil the road is on.
"You have to consider what the existing soils are," says John LaBar, Caltrans district material engineer. "Are they clay? Do we have to treat them with lime to make them more sandy to put the pavement on?"
San Diego has been blessed over the decades with abundant materials for roads and has had companies with long local histories supplying all that granite, sand and aggregate. Recently, though, suppliers of road ingredients have changed.
The Daley Corp. filed for bankruptcy last year. CalMat was bought in January by Vulcan Materials Co., which now runs the company’s vast operation off Stadium Way. H. G. Fenton Material Co. is no longer in business; its subsidiaries, Pre-Mixed Concrete Co., A-1 Soils Co. and East County (and North County) Materials Inc., were purchased last year by a New Jersey-based subsidiary of a British concern, Hanson plc. Those companies now are Hanson Aggregates Pacific Southwest Inc. And the old R. E. Hazard Co. site, also in Mission Valley, became Hazard Center several years ago.
The reduction of suppliers, or at least nearby facilities, concerns LaBar. "We’re running out of good material. We’ve got urban sprawl all over. The day may come when we’re going to have to import the sand for concrete from Mexico."
He points out that materials also could be trucked in from desert areas (where Caltrans still operates three sand and gravel yards, two in the Ocotillo area and one near Salton City) but that would be far more expensive than moving materials from Mission Valley or Carroll Canyon. In fact, Caltrans has gotten out of site operation altogether in San Diego; it’s now up to its road contractors to get their own sites and operate them within zoning and environmental guidelines.
By the way, also out in the desert, some of that plank road from the early days of motoring still exists, Mahserelli says. It’s off Interstate 8, out by the Sand Hills in Imperial County.
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