A variety of factors play into the creation of potholes. Since the average design life of asphalt is 20 years and much of San Diego has been developed in the past couple of decades, the pothole problem has been growing since the 1980s. The biggest factor, however, is weather.
In Eastern cities, the phenomenon of freeze and thaw creates pothole nightmares, as the subbase expands and contracts, causing “subbase upheaval,” according to Luque, and as the moisture that has intruded into the asphalt particles expands and contracts, causing the pavement to fracture. Further compounding the problem back East is the salting of roads during snowfalls. “The salt particles become embedded into the pavement,” said Luque. “The corrosive nature of the salt strips the liquid asphalt from the aggregate. It’s like taking away the glue that holds everything together. Secondly, the expansion of the built-up embedded salt particles combined with moisture fractures the pavement.”
In San Diego, the biggest contributor to an eruption of potholes is a rainy winter. “When it comes to asphalt streets, rain is your worst enemy,” Luque said. “In San Diego, we’re in a desert, but we still get our fair share of rain. In the road-maintenance business, we jump up and down and cheer for dry winters! The drought conditions, given the resources available for us to do our job, help us to not get further behind. When we have a really wet season, the water will find every weakness in the asphalt structure and it will pop. It’s called ‘spalling.’ Once you introduce moisture, that’s when the asphalt will start to break up.”
Another factor in pothole creation, says Luque, is the weight of the vehicles that pass over a street. “That’s called ‘vehicle loading.’ We could have millions and millions of passenger cars going all over the streets of San Diego every day, multiple times, and it wouldn’t bother us at all. One bus or one truck is another problem. Just one 18-wheeler is worth 3000 cars. When our roads were designed, I don’t think the designers ever envisioned articulating buses — those are the buses that are actually two city buses joined at the center like a caterpillar. That type of what they call ‘concentrated vehicle loading’ on the surface of the street causes a lot of problems for us — not only asphalt failure but potholes in general. Where buses stop at the bus stops, you’ll see where we’ve put big pads of concrete, because concrete is a lot harder. We are trying to develop programs to put bus pads at all the locations where buses stop, but there are tens of thousands of locations where they stop. It’s a constant problem for us, because the asphalt will shove. It looks just like the ocean — there are waves, because the weight of the buses has ruined the subbase structure and the asphalt has moved.”
Another, lesser, cause of potholes in San Diego’s mild climate is heat. “We do get some heat expansion,” Luque says, “because sometimes it gets kind of warm here. We don’t get a lot of it, and it doesn’t affect our concrete streets as much as it does our sidewalks. Every once in a while you’ll see how heat expansion just pops the panels up. They can rise as much as four feet. It’s the strangest phenomenon I’ve ever seen.”
Older parts of town are more likely to be pocked with potholes. “The populations are more dense in older areas — they’re not like subdivisions in Rancho Bernardo or Peñasquitos,” Luque said. “In North Park, they may take out 2 bungalows and put up 15 apartment units. Now you have 15 families living there, whereas in 1942 you had 2. You can’t stop progress, and next to water, construction is asphalt’s worst enemy.
“Anytime you disturb the street surface, it’s never going to be the same. Whether it’s putting up a new restaurant, new housing, or those lofts that are going up in Little Italy — they all need brand-new gas lines and feeds for water. Downtown is in this constant state of flux. There are also a lot more buses and commercial vehicles making deliveries downtown.”
The street division competes with other city services for its budget. “There is no average-sized pothole,” Luque explained, “but we have to come up with some kind of figure, otherwise how would we match resources to do what we need to do? The figure we use for the average pothole is $32 to repair. I could never find us enough money to fix them all.
“In the [2001–2002 fiscal] year, our budget was $765,000,” Luque continued. “[In the current fiscal] year, it’s up to $778,555, but that’s mostly for increased labor costs and inflation. As far as resources to fix the problems, there is no increase. We’ve been at static levels for the last few years. That’s where it starts to get a little political, but I’m more of an operations guy. I have to take what’s available to me and try to do the best I can to serve the public. If you asked everybody in the different divisions, they will all tell you that they are always begging for more money, because they can’t do everything they need to do. Now, elected officials have a hard job, because they have to figure out how to allot the money. I mean, we have to buy fire hoses, we need more policemen on the street, we need to build playgrounds. We need all these programs to take care of all these needs of our customers, and I’m just one of those needs. I need money to fix the streets and keep them in good shape. It’s a constant battle.
“We get money from gas taxes — it goes to the state and I have to ask for it back. We have general-fund money. We have TransNet money [from a half-cent sales tax] and money from federal and state programs for road and bridge maintenance. But my general-fund money is the same money that buys policemen to put on the street or do other things.”