Carol,
Private security doesn't have the power to enforce something like this. They also cannot give out fines. A police officer can control both the fence huggers as well as the Taxi problem in that area. As for hours to be on duty ; Maybe 10 AM to 6 PM as the woman who died got killed around 5:30 PM . A fine should be posted clearly on signs and fence to warn people that it will be strictly enforced for violators.