If the contract specifies the place of the work as the Mall, Mall street 1, as soon as someone crosses that line, it is ON and ticks as long as they leave the p

If the contract specifies the place of the work as the Mall, Mall street 1, as soon as someone crosses that line, it is ON and ticks as long as they leave the premises. I see no ambiguity there. If the time spent walking to the door is so important hire the fastest people.