A record-high 110,764 passengers took the Muir Woods Shuttle last year to visit the county’s most popular tourist spot, prompting Marin County Transit District officials to both praise the shuttle’s ability to handle heavy loads and worry about ongoing traffic congestion around the national monument. “The situation is going to get out of control this year,” said Steve Kinsey, who represents West Marin on the district’s board of directors. “It’s going to be outstandingly problematic. We have to recognize that.” District staff attributed the jump in shuttle riders to added service to Sausalito and a pilot program that brought limited weekday routes during the peak summer period. Up 7.6 percent from 2014, passenger numbers are expected to rise again this year with the loss of parking resulting from a deal struck between the county and the National Park Service that cut the number of parking spaces at Muir Woods down from 400 to 80 over the fall. Another 50 spaces are on the chopping block over the next five years. By park estimates, the monument hosts from 5,000 to 6,500 visitors on peak summer days; cars parked along the mile-and-a-half stretch of Muir Woods Road can reach 400 when they cram together along the shoulder, and as many as 1,000 park there daily. The district is hoping the park service will foot the bill for expanding shuttle service over the summer, a proposal Mr. Kinsey said would be “a good place to start and a great place to finish.” Mr. Kinsey also said it is unlikely the county will change the size of its shuttle busses, which local residents have called a threat to pedestrian safety. Rather, Caltrans “could be looking at improvements along that stretch of roadway with more pullouts and wider areas at the bends,” he said.