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Workers install a sidewalk on Serenade Drive near West Avenue. District 1 City Councilman Roberto Treviño says the city has about 1,900 miles of missing sidewalks. He advocates using precast concrete sidewalks instead of the traditional method of pouring concrete. Precast sidewalks, although more expensive, have been shown to be more durable.

A sidewalk on 300 block of East Woodlawn comes to an abrupt end. District 1 City Councilman Roberto Treviño says the city has about 1,900 miles of missing sidewalks. He advocates using precast concrete sidewalks instead of the traditional method of pouring concrete. Precast sidewalks, although more expensive, have been shown to be more durable.

Daniel Gonzalez walks along Waleetka Street in San Antonio, which is missing a sidewalk, in this 2017 photo. District 1 City Councilman Roberto Treviño says the city has about 1,900 miles of missing sidewalks. He advocates using precast concrete sidewalks instead of the traditional method of pouring concrete. Precast sidewalks, although more expensive, have been shown to be more durable.

Butch House likes to talk about concrete. And in San Antonio, that usually requires a conversation about clay soil, the unstable substance underlying home foundations, roads and the city’s 5,000 miles of sidewalks.

“In parts of downtown, like around San Pedro Creek, we have places where you’re hitting the water table in 5 feet. Worst soil in the world,” said House, president of Bexar Concrete Works, one of the largest makers of concrete bridge supports in the U.S.

“Around AT&T stadium, around Nolan Street, the soil is like some melted yellow chocolate soupy mess that just drips off the auger. That’s why San Antonio has so many foundation companies.”

District 1 City Councilman Roberto Treviño, an infrastructure aficionado whose Fiesta pin two years ago was a tiny metal sidewalk, shares House’s lament, but he believes that he has at least a partial solution — precast concrete sidewalks.

They’re not as contentious as public safety union contracts or light rail proposals, but Treviño says the repair and construction of sidewalks perennially tops every council member’s list of residents’ complaints. The stronger, longer-lasting form might cost about 20 percent more per square foot but has been shown to far outlast the traditional method.

On Dec. 19, ConnectSA, a nonprofit trying to shape transportation policy, released a report calling for 40 miles of new protected bike paths and 200 miles of new sidewalks by 2025. The two can and should be linked, Treviño says, and he wants to make sure the new “pedestrian mobility officer” the city is looking to hire understands that.

“I can get really, really deep in the weeds on this topic,” warned Treviño, an architect. His obsession has earned him a City Hall nickname, “Luke Sidewalker.”

“We have 1,900 miles of missing sidewalks in San Antonio,” Treviño said. “That’s 38 percent of our 5,000 miles of sidewalks. These aren’t the ones that are old and cracked. They simply do not exist.”

When you follow him into the weeds, you learn that the average cost of a code-compliant sidewalk can reach $28 per square foot and a lot more with retaining walls or sloped curbs. That’s almost $1 billion to meet the city’s total need, and “we don’t have that money” — but the city could double the effect of the money it does have by using the more expensive but more durable precast method, he says.

The city’s Transportation & Capital Improvements Department, or TCI, says precast sidewalks will cost about one-third more than conventional ones — Treviño says the difference is closer to 20 percent — but industry sources agree that precast sidewalks can easily last 60 to 80 years or more. On San Antonio’s clay soils that dramatically expand and contract with heavy rain and severe heat, a traditional “pour-in-place,” or PIP, sidewalk can crack within five years, maybe three, according to concrete pros.

It is that invest-for-tomorrow philosophy that Treviño hopes to sell to TCI, his fellow council members and residents who might be used to a Band-Aid approach to infrastructure repairs.

Precast concrete is hardly a new technology. You see it in the traffic barriers and bridge supports on interstate highways. It’s denser and has about three times as much tensile strength as a PIP structure, but using precast for a city sidewalk is not common in the U.S., according to experts familiar with both.

The advantages of precast vs. pour-in-place can be considerable. PIP usually takes longer to install, about three days for a typical 50-foot-long residential sidewalk, say experts, compared with one day for precast. A PIP sidewalk can’t be done in the rain. Both require about the same 2- to 4-inch underbed of fine gravel, but precast doesn’t require the time-consuming wooden forms into which traditional concrete is poured.

Precast sidewalks can hinge at their joints to better adjust to an uneven landscape.

“Pour-in-place is something we’ve done for years,” said Jeff Pepper, a superintendent with Easter Concrete in Helotes for more than 20 years. “If done correctly — and we have rigid rules when working for the city — it is a long-term product. But there’s a huge variation in the quality of contractors.”

Shoddy placement of metal reinforcement rods, or rebar, within traditional PIP sidewalks can result in a cracked sidewalk within three years — “we see it all the time in walks we have to tear out,” Pepper said.

Precast walks are made in factories in long, shallow molds, like giant ice cube trays, where the rebar is usually stronger and placed consistently in the middle of the slab.

Poorly made sidewalks, often done by crews working under the pressure of lost rain days and low-bid economics, might pass unnoticed in other cities. In San Antonio, sidewalks crack and wobble like they’ve gone through mini-earthquakes, their jagged edges pitched upward.

At Treviño’s urging, the city conducted a trial in 2016 of 1,500 linear feet of precast vs. PIP sidewalks in the 2000-2200 block of La Manda, from Vance Jackson to West.

Mike Frisbie, former director of TCI, deemed the trial a success for precast and scheduled another test the next year on Tiffany, from Briarfield to Marlbrough.

The city wants to put a priority on building sidewalks in high-use areas — approaches to VIA Metropolitan Transit bus stops and on the way to schools, churches, senior citizen centers and commercial areas.

Razi Hosseini, the interim director of TCI, said precast sidewalks fared well in the tests, especially compared with what happened to traditional walks in 2018’s above-average rain that followed some dry months.

But Hosseini isn’t suggesting San Antonio should use precast technology for all its sidewalks — they’ll work best in residential areas where there aren’t a lot of structural oddities, such as mailboxes on posts, utility poles and cumbersome retaining walls, he said — but he hesitates to put a target percentage on it. The city has about $19.8 million allocated through 2019 for building new sidewalks, he said.

Treviño said there’s no reason the city couldn’t aim for using precast for 20 to 30 percent of the remaining 1,900 miles of sidewalks it needs to construct.

“I’m sold on them,” Treviño said last month. “And I’m going to show that it all can be done — in my district.”

House, the concrete factory president, said his company has made millions of square feet of precast concrete bridge decking, supports and traffic barriers over the past 50 years and that San Antonio would be wise to search for such long-term solutions.

“San Antonio has to think more long-term about its major projects,” said House, a Texan who worked in construction in Rotterdam, Holland, for two decades and came to appreciate the European approach to infrastructure. “We have to use new technology and more progressive thinking.”

Bruce Selcraig is a staff writer in the San Antonio and Bexar County area. Read his stories on our free site, mySA.com, and on our subscriber site, ExpressNews.com. | BSelcraig@express-news.net

Bruce Selcraig is a senior staff writer and former U.S. Senate investigator. A native Texan, he's written for The New York Times, The Atlantic and Smithsonian, and was an investigative reporter with Sports Illustrated in the 1980s. His work has ranged from refinery explosions to Mafia-backed sports agents and a hunt for the real Robinson Crusoe, a distant Scottish relative.