The Metro-North Railroad New Haven Line is the busiest train line in the United States, but you wouldn't know that by taking a look at statistics released last week for the Danbury branch.The branch line, which serves Wilton as well as Ridgefield, Redding and Bethel, was down 2.4% for the year in total ridership, according to data supplied by the state Department of Transportation.A total of 782,796 rides were taken on the branch for the year, compared with 802,117 the previous year.Most of the dip was in rides down the line between towns, down 7.6%. The number of riders who commute to New York City each day was up slightly, by 0.8%, at 503,429 rides, up from 499,520 the previous year.The railroad has three branch lines. The New Canaan branch is the largest, with more than a million rides per year. Total ridership was down there, too, by 1.1%.There is also the Waterbury branch, which covers the Naugatuck Valley towns of Ansonia and Seymour, where ridership was down for the year by 1.4%.The data results drew fire from Sen. Richard Blumenthal (D-Conn.), who joined other legislators in calling for improvements to service.Bad service is the reason ridership is down on the branches including the Danbury-to-Norwalk branch, Blumenthal said in a joint press statement with Sen. Chris Murphy (D-Conn.) and U.S. Rep. Elizabeth Esty (D-5).The lawmakers sent a letter asking MTA-Metro-North Railroad to provide a detailed plan for improving service and increasing ridership on the Danbury, Waterbury, and New Canaan branch lines. In a letter to MTA-Metro-North Railroad President Joseph Giulietti, the members of Congress cited clear examples of when service improvements along the branch lines have led to increased ridership, and when lapses in service have led to decreased ridership. They emphasized the importance of reliable train service to Connecticut residents and argued that upgraded train service along the three branch lines will increase ridership."Recent reporting and MTA ridership data suggest that consistent lapses in services on the Waterbury, Danbury, and New Canaan Branch Lines have led to a decline in ridership. With that in mind, we write today to convey our deep concern about this trend, particularly because of its cause - poor service," wrote the members of Congress. "Riders are frustrated, and they want better service. Better service will increase ridership, which will increase investment, creating a virtuous cycle benefiting commuters of all stripes. Therefore, we respectfully ask you to provide us and branch line riders with your plan for improving service and increasing ridership on the branch lines in the near- and long-term."At the station near Wilton Center, rider Glenn Orsher of Wilton had choice words for the Danbury line."It is the poor stepchild of the railroad," Orsher said while waiting for the 7:20 a.m. train to New York City.Importantly, he noted, it is a diesel train."The equipment is the oldest on the line, and it breaks down," Orsher said.There are times when local residents drive to Norwalk to take the main line rather than deal with the branch line issues, he said."Yes, it's bad," said rider Paul Merolla of Wilton, also waiting for the 7:20 to Grand Central Terminal. "It's very old equipment. That's part of the problem."Another issue is that the line has a single track, said another rider who would not give his name.However, state officials are not convinced that declining service levels are the problem. Ridership always fluctuates, said Judd Everhart, spokesman for the DOT."Ridership numbers vary up and down all the time - reasons can include the weather, gas prices, employment levels, and even track improvement projects that require temporary busing around certain sections of the tracks between stations," Everhart said.