Amtrak’s Downeaster will increase track capacity and add a fifth daily round trip in 2007, a $6 million project that includes New Hampshire’s contribution of $1.6 million of federal air quality improvement funds.

In the meantime, Amtrak has finessed the scheduled arrivals and departures on the route to better coincide with commuter hours. Weekday morning trains now depart Dover at 6:51 a.m. and 9:01 a.m., arriving in Boston at 8:25 and 10:30 a.m. respectively. Afternoon trains depart Boston’s North Station at 5 and 6:20 p.m.

Concord Trailways and C&J Trailways will also operate an 11 p.m. “Downeaster” bus from North Station. That route will be taken up by train service when construction is complete. All trains also stop in Exeter and Durham.

A schedule of five round-trips has been identified by the Northern New England Passenger Rail Authority and Amtrak as a key element to attracting more passengers to the Downeaster service.

The Downeaster route, which runs from Portland to Boston, is a partnership between New Hampshire, Maine and the Federal Transit Administration. The group has finalized an agreement with Pan Am railways, which owns 78 miles of track between Portland and Plaistow, to fund a construction program to improve track capacity and eliminate infrastructure constraints along the railroad right-of-way that have been a barrier to initiating additional frequency on the route.