Residents are invited to lend a hand with a trail project in the town’s landlocked parcel. On Friday, Saturday, and Sunday the Friends of the Landlocked Forest and the Greater Boston chapter of the New England Mountain Biking Association are building three boardwalks to improve access across muddy areas in the forest. Volunteers are needed for construction and moving lumber. Work hours are 9 a.m. to 3 p.m. Friday and 8 a.m. to 4 p.m. Saturday and Sunday. Volunteers are welcome for any and all of those hours. The meeting place each day will be the kiosk in the parking lot on Turning Mill Road in Lexington. Participants can park there on Friday, but on Saturday and Sunday they are asked to park in the staff lot at the nearby Estabrook School in Lexington. Volunteers are encouraged to bring work gloves, bug spray, sun screen, and a water bottle. Lunch, snacks, and tools will be provided. Registration is encouraged. To sign up or for more information, contact Bill Cohn, the project leader, at email@example.com. The landlocked parcel is 250 acres of town-owned land that is so named because Burlington residents, separated from it by Route 3, , have access to it only through Bedford and Lexington.