Auto Insurance Claims: Liability on construction site, ordinance code, t park

Question
Hi,  I'm a security Guard for construction sites on and near our University campus. So there is lots of people with very little parking available.  I and another guard arrive at work around 9 pm.   We have had many issues with people parking on the site.  The site is open.  Due to limited space the builders can not put a fence around the grounds.  We keep putting no parking signs up.  But they must be a high Demand item because they keep getting stolen.  When we do catch the people we just tell them they can't park here because there is a possibility that their vehicle could get Damaged.  They must not care if anything happens.  One student told me that if any damage was to happen it would be the liability of the site owner to pay for the repairs.  Also since it is not clearly marked with a ordinance code they are free to park here and we can not have the car towed.  
Is This true?  who is liable for non employee's vehicle while on site after business hours? Also can we have a car towed at owner expense and liability?  Any info you can give will help... Thanks, Angela

Answer
Hi Angela,

Each state law may be different. However it seems to me that if the university owns the property, they have the right to restrict who parkes on it. They should post signs that clearly state "No Parking - violators will be towed at owners expense". Then they must have a zero tollerance policy. If someone parks there, have them towed right then. The word will spread quickly that you are not playing any more.  

I hope this helps
Richard Hixenbaugh