Lynnfield residents approved a $7.8 million athletic fields project on a 551-to-40 vote, which was far more than the two-thirds majority needed, at Monday’s annual Town Meeting. The project includes building three multiuse fields at the high school, including a main stadium field; rebuilding the softball and baseball fields; and the construction of a building for bathrooms, concessions, storage, and team meeting rooms. The fields will have artificial turf, and some will be lighted. The plan also includes upgrades to athletic fields in numerous other locations in town. The project will be funded without a Proposition 2½ override, with much of it covered by new tax revenue resulting from the MarketStreet Lynnfield development at the former Colonial Golf Course. In addition, a private fund-raising campaign is planned for upgrades of fields at the middle school.