PORTLAND, Ore. -- Thieves have hit a Portland light-rail project hard, taking more than $100,000 in tools, machinery and building material since work began a year ago.

The transportation project that goes along Interstate 205 is aimed at expanding mass transit to Portland's east side and the suburbs beyond.

Though the incidents are rarer since the start of the project as contractors have stepped up security, thieves are getting bolder -- and the losses are eating into profits, said Mark Bodyfelt, a project manager for the companies in the joint venture.

Early last week, for example, a trailer containing $30,000 worth of equipment used for laying track was stolen.

But the trailer was outfitted with a GPS tracking system, and Clackamas County sheriff's deputies recovered it a few miles away.

A few days later, an electric generator valued at $1,700 was stolen in broad daylight, while a five-person crew worked less than 50 feet away.

Crew members were overhead working on an interstate overpass when they noticed their power tools weren't working. Thinking the generator was out of gas, they went to inspect it and found no generator.

The light-rail project is along an isolated stretch of highway and home to transients who gather and sleep under the overpasses, said Gil Millett, a deputy with Clackamas County Sheriff's Office.

Such a project can't be protected so easily as, for example, a high-rise building, builders said.

Millett said "opportunity" thefts of tools and materials lying around are most likely the work of transients, while the larger thefts are more likely the work of criminals involved in metals thefts to pay for drugs.

The March 1 sentencing of Anthony Fleming, who received 45 months in jail for four crimes, gave investigators some hope.

"One of our main construction site thieves just got sent to prison," Millett said.

But builders expect thefts to spike again in coming months when workers begin laying copper wire.

"We haven't gotten real earnest in running a lot of wire yet, so we expect that we'll get hit harder. It's seven miles of easy pickins," said Robby Eidem a safety manager. "So we're expecting trouble."