New method for laying cable tested 

A potentially revolutionary new approach to laying phone and cable lines could help improve the condition of San Francisco’s oft-neglected streets and sidewalks.

Such infrastructure is normally laid in wide, deep trenches that are covered over after the wiring has been put in place.

The outlines of those trenches can remain visible long after they’re refilled and they can lead to pot holes.

But, following an emerging international trend, cable was laid instead along a narrow and shallow trench that was cut with a specialized saw into a sidewalk in the Golden Gate Heights neighborhood.

The so-called microtrench was sawed out, filled with cable and then covered back over nearly a year ago and the Canadian company that sold the cable said it has held up well.

“You don’t have to be an engineer to know that a ½-inch trench as opposed to a 2-foot trench is going to have less impact,” said Gary Stahlbrand, the U.S. agent for Canadian company TeraSpan, which specializes in microtrenching products.

Stahlbrand recently visited San Francisco to inspect the microtrench in Pacheco Street, between 11th and 12th avenues.

“There was no degradation to the road and everything is looking just like it did the day that we installed it,” Stahlbrand said.

Stahlbrand said the company’s biggest obstacle to mass-marketing its microtrenching products is resistance from municipalities, which fear that the narrow and shallow wires could easily be damaged by maintenance work.

The San Francisco Department of Public Works plans to conduct its own analysis of the condition of the microtrench-affected sidewalk soon.

“We allowed it because we want to see if this is a less impactful way to install utilities in the streets,” department spokeswoman Christine Falvey said. “We’re going to have to see how it performs.”

If the department is happy with the result of the microtrench after its one-year birthday, it plans to allow the technique to be deployed more widely, according to Falvey.

Microtrenching can improve the overall condition of streets, but it’s also popular with phone and technology companies because it provides a faster and less expensive way of installing underground wiring.

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