COTATI ? Cotati-based medical transit provider ProTransport-1 has been approved to offer service in Modesto, extending the company's expansion that now includes eight operating centers extending as far as Seattle.

"We've doubled in size every year since we opened in 2000," said founding partner Mike Sechrist. "The demand is everywhere. And now with Seattle and Modesto there's no reason why we shouldn't double in size again next year."

Based in Cotati, ProTransport-1 provides medical transportation services for people like renal patients who need to go to dialysis several times a week or those with chronic ailments being discharged from a hospital and into a nearby skilled nursing or rehabilitative care facility.

"Most of our business is hospital discharges," Mr. Sechrist said. "There are hundreds of thousands of patients every month who go into the hospital with injuries that need rehabilitation. And the industry has started pushing them out faster into convalescence homes. They need to be transported there. So with every problem with the industry there is an opportunity."

ProTransport-1 does not service emergency calls. The company makes a profit through the sheer volume of runs it makes and efficiencies from computer dispatch software and other technologies.

On Dec. 11, the company surpassed 40,000 calls, effectively doubling its call volume from the previous year. And in 2006, the company will bring in revenues topping $13 million, Mr. Sechrist said.

Patients who use ProTransport-1 services are most likely to be around age 70 and on Medicare. As a result, approximately three quarters of the company's accounts receivables come from Medicare reimbursement, with the remainder from Medi-Cal and private pay, Mr. Sechrist said.

Demographics are important because the company uses them as a metric for gauging the feasibility of potential new territories. Before the company entered the Seattle market, for example, Mr. Sechrist and other executives examined the average age of the population, the number of skilled nursing units per square mile and the local rates of Medicare reimbursement.

"Obviously we're a demand-driven service," he said. "We have to take those factors into account."

Formerly located in 6,400 square feet of office space in Rohnert Park, ProTransport-1 moved its headquarters to 720 Portal St. in Cotati, effectively quadrupling its office space to 24,000 square feet. From here Mr. Sechrist and two other executives ? Vice President Dennis Robinson and founding partner Elaina Whorton ? manage a fleet of 40 vehicles in eight separate locations, six of them around the Bay Area.

After examining ProTransport-1's operation at the request of Modesto City Council, Modesto Police Detective Mike Hermosa urged officials to approve the service because of the need.

"With our ever-growing population, it is necessary to provide the citizens of Modesto more options in this area," he said.

Ontario-based competitor Priority One, which already operates in the Modesto area, questioned the need for another operator.

"The market is already saturated," Priority One Vice President Jim Karras said. "It's not like a regular business where you can go out and market and get more customers. There is a fixed number of transports each day and all you can do is compete for actual share."

Mr. Karras said that ProTransport-1's entrance into the market could actually drive up the cost to consumers by lowering the overall profits generated by each ambulance in the region.