Ottawa security staff want to quadruple the number of parks equipped with surveillance cameras to enforce a closing time of 11 p.m.

Cameras are already installed at Strathcona and Cahill parks as a pilot project, but the city's head of security, Bob Gauvreau, wants to set cameras up in five or six more parks to enforce the bylaw that bans park use between 11 p.m. and 5 a.m.

"Patrolling that would be an enormous job," he said, adding that the city has over 700 parks.

The cameras are switched on at 11 p.m. After that, people walking by will trigger the camera's motion detector, allowing security staff to see them anddecide whether tocall police. A nearby loudspeaker allows security staff to address people in the park.

City officials recommended thenighttime closuresto reduce late-night partying and vandalism, and it was passed by council in 2005.

But a building in Strathcona Parkoutfitted with several city cameras is also covered in crude drawings, and a nearby wall wears a many-coloured coat of graffiti, raising questions about the camera systems' effectiveness. Gauvreau estimates they cost $60,000 per park to run.

When asked if park users might complain that the cameras violate their privacy, Gauvreau said they would not, because the cameras are only turned on after the parks close, and signs inform people of their presence.

He added that many similar cameras are already installed on museum grounds and at city pools to discourage vandalism.