Brake Smell on a Charter Run
At 3:00 p.m., a 47-passenger motorcoach is descending a 6% grade in western Maine. There are 42 passengers aboard, including six children and two wheelchair users; luggage is loaded in the lower bays. The grade is three miles long, and the driver has been using the service brakes steadily to hold 35 mph. The speed has crept up to 50 mph, the brake pedal feels low, and the driver smells hot brake lining. A wisp of smoke appears at the right rear. The engine retarder is available but has not been used. A paved pullout is about a quarter mile ahead, guardrail is on the right, and traffic is behind. The driver must decide whether to continue to the bottom, stop at the pullout, or evacuate immediately.
1. What should the driver do in the next few seconds to regain control and reach the pullout?
Read the worked answer
The driver should act immediately rather than wait for the bottom. First, release the steady brake pressure and downshift to a lower gear so engine braking helps; then activate the retarder at a safe setting. The driver should apply the brakes firmly but intermittently, not ride them, and use the pullout to stop. Hazard flashers and horn should warn traffic, and the driver should keep the bus straight and avoid sudden steering with the guardrail close. If speed cannot be controlled, the driver should look for an escape ramp or a safe run-off area, but should not aim for the guardrail. The key is to reduce speed before the pullout and stop fully off the travel lane. Continuing to the bottom with a low pedal and smoke risks complete brake fade.
2. Why are the low pedal and smoke significant, and what should the driver do after stopping?
Read the worked answer
Smoke and smell mean the brakes are overheated; a low pedal or weak application suggests fade, air loss, or a mechanical problem. In a motorcoach with air brakes, a low pedal is not normal and may indicate a failing component or air pressure problem. After stopping, the driver should set the parking brake, keep the transmission in gear or park, and shut down only if safe. Chock wheels if leaving the seat. Do not spray water on hot drums or discs; rapid cooling can crack them. Inspect for fire, leaking air, and damaged lines. The bus should not continue until a mechanic inspects the brakes and confirms air pressure and braking performance. If there is fire or smoke in the cabin, evacuate immediately.
3. How should the 42 passengers, including two wheelchair users, be managed during the stop, and when is evacuation required?
Read the worked answer
The driver should first stop safely, then address the passengers calmly. If there is no fire or immediate danger, keep them seated with seat belts on, tell them there is a mechanical issue, and ask them to remain calm while the driver inspects. The driver should designate helpers for the wheelchair users and know the emergency exits. Evacuation is required if there is fire, smoke in the cabin, a fuel leak, or the bus is stopped in a dangerous travel lane. In that case, evacuate away from traffic and uphill/upwind, assist the wheelchair users with the lift or ramp if time permits, and move the group at least 100 feet from the bus. Someone should call 911 and dispatch. The driver should account for all passengers and not move the bus until cleared.