Case: One month of city bus tire monitoring
The urban environment is challenging for bus tires. The hectic environment, high bus utilization, curbs, deceleration bumps and road damage pose a risk that is difficult for the operator to manage. In addition to the obvious safety risk, a tire failure on the line incurs significant costs in the form of contractual fines, on-road repairs, towing and replacement car and driver costs. At its worst, a ruptured tire causes damage to the chassis and bodywork of the vehicle, as well as a significant risk of injury to outsiders adjacent to the ruptured tire. There is no price for the resentment caused to passengers by an interruption, but it is, of course, significant.
This article presents the results of E3 Innovations ’sensor-free real-time tire monitoring over a month on 30 buses from the city bus operator. Critical tire damage was detected and prevented in four cases, one per week. Statistically, it can be concluded from this that in a fleet of 200 buses, damage should be found one per day. Sure, the findings are from April, which is the most challenging of the months for tires. Not all tire damage results in disruption, but driving at low air pressure results in costs and emissions in the form of increased energy consumption and reduced tire life. Case examples are potentially serious injuries leading to driving interruptions, in addition to which numerous decreases in tire pressure have been observed.
Case1: The left front tire deflates at 1 bar per hour. System warning after two hours (-2 bar). Time to react after warning before critical depletion 2.5 hours. The driver did not notice a drop in tire pressure before warning from the system.
Case2: Bogi axle, left. Slow and steady emptying. Caused by a screw on the tread. Slow deflation was observed before the pressure drop resulted in more extensive tire damage.
Case3: Tire frame damage. An increase in the dynamic diameter of the tire was observed, which was known from previous observations to mean an explosion of the tire within the next couple of weeks.
Case4: A leak in the bogie tire would have emptied the tire in a few days. Brake imbalance was observed on the same axle.