The State Highway Administration will more than double the number of parking spots at the Davidsonville Park and Ride lot, a move officials say is a response to increased demand.
Plans call for adding 240 spaces to the 210 now there. Construction, likely to start next summer, is expected to be completed next fall, said SHA spokesman David Buck.
Some days the free lot — on Route 424 off U.S. 50 — is so full that drivers who don't find a space leave vehicles lined up along the lot's inner curbs and grassy islands.
Vehicles have also been left parked along the road, Buck said, and they've overflowed into nearby neighborhoods as commuters hurry to catch early buses to Washington and share rides with other commuters.
"There's never a space," said Carrie Parvis, an Odenton woman waiting for her daughter in the lot after the morning rush hour on Thursday. Parvis planned to pick up her granddaughter there and take her home to baby-sit while her daughter, a nurse, was at work.
"A lot of people will illegally park by the curb," she said. "People park here on the highway, too, I've seen five or six on the grass."
Police have started ticketing cars parked illegally along Route 424. Drivers complained that those vehicles blocked their view of oncoming traffic on Route 424 as they tried to leave the lot, Buck said.
The lot expansion is expected to cost between $2.5 million and $3 million, and the lot will remain open during construction, with some spaces blocked as the new section is connected to the existing one.
The Davidsonville lot expansion will come about three years after the state added 155 spaces to a park-and-ride lot in Riva, bringing it to 825 spaces, and as highway officials look to expand the commuter lot in Waysons Corner in southern Anne Arundel County from 100 to 175 spaces, Buck said.
Buck said use of commuter lots has grown in recent years, along with the popularity of commuter buses and ride-sharing programs.
"The Davidsonville park-and-ride overcrowding comes as no surprise, with the annual average price of gas to-date at the most expensive on record and more people going back to work, given the improving economy," AAA Mid-Atlantic spokeswoman Christine Sarames Delise said in an email.
Terry Owens, a spokesman for the Maryland Transit Administration, said commuter bus ridership has climbed in recent years, and the two lines for which the Davidsonville lot is the last stop before the buses reach Washington are "especially busy." For one, ridership has grown to 31,000 a month, and for the other, it's 20,000 a month, he said.