The town’s Zoning Board of Appeals is meeting Tuesday at 4 p.m. in Town Hall, and the sole item on its agenda is the Parc at Medfield, a proposed 96-unit affordable housing development off West Street. Tuesday marks the end of a 40-day period that the board had to reach a decision on the project, which is being proposed by the Gatehouse Group under the state’s Chapter 40B affordable housing law. Critics have raised concerns about pedestrian safety in the area, wetlands issues, the impact on schools absorbing additional children from the development, and traffic. A favorable decision by the board may win some concessions from the Gatehouse Group that would help address the complaints. Since less than 10 percent of Medfield’s housing stock qualifies as affordable, the Chapter 40B process allows a development that includes affordable units to bypass certain local zoning restrictions. If the board rejects its proposal, Gatehouse Group can appeal to the state and could win approval without concessions.