Maurice Scott opened the tailgate of his pickup, revealing enough quick-drying Krylon industrial spray paint to palpitate the heart of a graffiti artist.

"Anything within 25 feet, we have to mark," said Scott, an underground-utility locator for USIC, a Peco Energy Co. contractor.

Scott consulted a map of the underground circuitry at 22nd and Walnut Streets in Center City, where a four-story condominium building is being constructed. He confirmed the location of the wires using an electronic tool that wailed when it detected underground electricity. Scott marked the pavement with red paint indicating Peco's buried electrical lines.

After workers for other utilities tagged the site - yellow paint for gas and steam, blue for potable water, orange for phone and cable - the sidewalks and streets around the site were transformed into a kaleidoscope of colorful hieroglyphs that mapped out the hidden network of pipes and cables below.

"It's crowded down there," said Dave Haverstick, Peco's manager of damage prevention. "In big cities like this, it's very challenging."

The state's Underground Utility Line Protection Act, which requires utilities to mark their underground lines to prevent infrastructure damage, is set to expire at the end of this year. Legislation to renew the Pennsylvania One Call System is hung up in a Harrisburg labyrinth that makes the underground utility matrix look simple by comparison.

"With other things going on in the legislature, they've been distracted, to say the very least," said William G. Kiger, president of Pennsylvania One Call System Inc., the Pittsburgh-area nonprofit that manages 811 phone calls from excavators.

The Pennsylvania Public Utility Commission is supporting legislation that would transfer enforcement of the law from the Department of Labor and Industry to the PUC.

The commission says it could reduce by half the 6,000 annual line hits on utilities, most of which occur in dense urban areas. And those are just the reported hits.

"About 80 percent of the damage is related to industries we already regulate," said John F. Coleman Jr., a PUC member. The U.S. Department of Transportation's Pipeline and Hazardous Materials Safety Administration and Gov. Wolf's Pipeline Infrastructure Task Force have recommended that the PUC take over enforcement.

A beefed-up, six-person inspection unit would cost $770,000 a year, which has raised concerns for State Rep. Robert Godshall, the powerful Montgomery County Republican who heads the House Consumer Affairs Committee. Godshall did not respond to a phone message or an email last week.

Coleman said the additional cost would be assessed to utilities, which would pass them along to customers. The cost is reasonable, he said, and would be offset by reduced repairs for damaged facilities, along with fewer outages, injuries, and property damage from line hits.

"What is the cost of the loss of life here?" he asked.

Senate Bill 1235, which was ready for introduction last week by State Sen. Lisa Baker (R., Luzerne), also would remove exemptions from the notification requirements given to PennDot, municipalities, and some natural-gas pipeline operators. Those exemptions make the state ineligible for several federal safety grants, costing the PUC and PA One Call about $250,000 a year.

Previous attempts to eliminate the exemption for operators of 12,000 miles of natural-gas gathering pipelines, which connect gas wells to larger regulated pipelines, were fiercely opposed by the Pennsylvania Independent Oil and Gas Association (PIOGA), which says the reporting requirement would impose unsustainable costs on small gas producers.

The industry's arguments lost some of their weight last year, after a contractor who had called 811 before digging struck an unmapped Marcellus Shale gas pipeline in Armstrong County that had been installed in 2011. The ruptured pipeline exploded, fatally injuring a backhoe operator.

Louis D'Amico, PIOGA's president, did not respond to an email seeking comment.

Coleman said he understands the cost concerns of small conventional gas producers and is willing to consider a compromise relaxing the requirement to enter maps of their legacy pipelines into the One Call system. They would still be required to mark all lines in any excavation area.

But Kiger, head of the One Call System, said all existing gathering lines should be mapped so that the pipeline owners would be notified when excavators propose to dig nearby.

"It really doesn't take that much effort to enter the map data into the system," he said.

The One Call system, which operates nationwide under the aegis of the Common Ground Alliance, also establishes a clear line of responsibility if an accident occurs. Even companies that do not participate in the system can be found liable if their underground lines are damaged.

Kiger said Sun Pipe Line Co. was held partly liable for a 1983 gasoline spill that occurred when a cable-television operator struck an unmapped Sun pipeline while installing new underground lines. Sun later became a member of the One Call system, he said.

Liability concerns clearly motivated the actions of the Peco contractor who marked out the intersection of 22nd and Walnut the other day. Scott, whose official title is damage-prevention specialist, pulled out a digital camera when he was done and photographed the lines he had just painted.

"We document," said Haverstick, the Peco supervisor. "We take pictures and time-stamp when we were here. We would have a history of any actions that were taken."

If there was any damage later, Peco would conduct an investigation to establish whether the excavator had called 811, whether Peco's contractor had properly marked the underground lines, and whether the excavator had prudently dug around the buried utilities.

"The onus is on us to prove we were here," said Haverstick.