To prevent corruption and ensure good performance, the guards were paid handsomely and supplied with a generous pension. The mail was their sole charge, meaning that they had to deliver it on foot if a problem arose with the coach and, unlike the driver, they remained with the coach for the whole journey; occasionally guards froze to death from hypothermia in their exposed position outside the coach during the harsh winters (see River Thames frost fairs). The guard was supplied with a timepiece and a posthorn, the former to ensure the schedule was met, the latter to alert the post house to the imminent arrival of the coach and warn tollgate keepers to open the gate (mail coaches were exempt from stopping and paying tolls: a fine was payable if the coach was forced to stop). Since the coaches had right of way on the roads the horn was also used to advise other road users of their approach.