 Comprising an average of 10 blocks per precinct, they are collectively grouped into up to nine neighbourhoods per new town.The Housing and Development Board, the sole public housing planner, designer and builder in the city-state, adopted the precinct concept in 1978, based on its understanding that social interaction and community bonding can be optimised in a smaller planning unit compared to a full neighbourhood.In addition, precincts are expected to evoke a stronger sense of security, although they are not physically fenced, and do not restrict movements for residents or outsiders in any physical way.