FORT WASHINGTON, Pa. - Counting to himself as the diesel-powered pile driver repeatedly slams a bridge support beam deeper into the ground, Harry Freed is quickly earning what could best be called a real traffic headache.

Slam! ... Slam! ... Slam! Nearly once a second the smoke-spewing machine goes, jostling the Pennsylvania Department of Transportation inspector's hard hat the slightest bit each time.

Freed's eyes remain steady as the girder is driven far enough into the soil to support a bridge that will carry Route 309 over Route 73 in eastern Montgomery County. He jots down notes to track how many times the beam has been struck and how far it has gone in.

"It can be monotonous. It's the same thing all day," said Freed, adding that it's draining to monitor pile driving for 30 to 40 minutes at a time over a 12-hour shift. "You have to keep your mind focused. Your mind can drift."

The molar-jarring task, as well as the efforts of others along Route 309 and at other work sites in the congested Philadelphia area, are part of PennDOT's efforts to try to alleviate traffic headaches in the state's most heavily traveled region.

On a recent weekday morning, crews working along Route 309 were laying the foundation for automotive and railroad bridges, preparing new traffic lanes, and doing early-stage work on a revamped interchange at Route 309 and the Pennsylvania Turnpike.

The $300 million in improvements to a 10-mile section of Route 309 are geared toward making traffic run more smoothly on the expressway, which carries 50,000 to 65,000 vehicles a day between Philadelphia and its northern suburbs. PennDOT hopes to have the road widening, bridge upgrades, resurfacing, sound barrier construction and other improvements done by 2008.

"What it will do is take an outdated highway designed in the 1950s and update it to present-day standards," PennDOT spokesman Gene Blaum said. "Basically at the peak travel hours, merging into traffic at certain locations is difficult."

Construction crews like the ones on Route 309 are a common site to Pennsylvania drivers, a heavily traveled state constantly trying to fill both potholes and budget gaps.

There are typically about 600 to 800 construction and repair projects under way at any given time, employing about 61,000 workers, most of them contractors, according to PennDOT. For the 2005 calendar year, the agency has awarded $1.3 billion in contracts.

The workers say that, while drivers aren't always happy to see them, the roads desperately need to be modernized.

Decked out in a red hard hat and mirrored shades, carpentry foreman Pete Knies worked a short ways down the road from Freed, leading a team building the foundation for a temporary railroad trestle over Route 309.

A cry of "Fire in the hole!" cracked the crisp, late-morning air as Knies and his crew were building supports for the concrete trestle. When it's done, the 750-foot bridge will carry Norfolk Southern rail traffic until a 1950s-era bridge is replaced.

"It's all got to be right at the bottom to be right at the top," said Knies, who works for Nyleve Bridge Corp. "They're counting on you to get this done in an expeditious manner."

Workers say they feel the pain of motorists slowed by construction delays - and suffer their own pain from fixing the roads. Sore muscles, bad backs and calluses are just the start. There's also the risks of construction vehicles backing up, heat, gas lines and angry motorists.

A car horn blares as project manager Stephen Ryan is touring his section of the Route 309 project and he instinctively snaps his head to spot any danger. Seconds later, Ryan and his colleagues are dodging pieces of heavy equipment after trucks moving in reverse give off steady warning beeps.

"You will see every crazy thing people will do behind the wheel of the vehicle," Ryan said. "You've got 60,000 cars a day trying to kill you, and then it's one of your own trucks."