Cold-Morning Pre-Trip With Four Defects
At 5:55 a.m. the temperature is 19°F and the lot is glazed with freezing drizzle. You are assigned a 2016 conventional bus with air brakes, a 48-passenger capacity, and a route that begins with a 7 percent downgrade on a two-lane road with a curve at the bottom. During the pre-trip inspection you find four problems: the low-air-pressure warning buzzer does not sound until the gauge reads 45 psi; the left rear slack adjuster push rod travels past its stroke mark; the right front tire has 3/32 inch tread; and the stop arm extends, but the red lights on the arm do not flash. The dispatcher says a replacement bus is 25 minutes away, and your first stop is at 6:20 a.m. with 22 students waiting. You have a two-way radio and a cell phone.
1. Which of the four findings place the bus out of service, and what is your immediate plan for the 6:20 a.m. stop?
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All four findings matter, and each independently keeps this bus out of service. The low-air warning must activate before pressure falls below 60 psi; sounding at 45 psi means the warning is late and the driver may not get enough notice of a brake failure. A push rod past its stroke mark means the foundation brake is out of adjustment and stopping distance is unpredictable. A steering-axle tire at 3/32 inch is below the 4/32 inch minimum for front tires. The stop arm red lights are required warning equipment; without them you cannot legally control traffic for loading or unloading.
So you do not run the route in this bus. Notify dispatch, enter the defects on the driver vehicle inspection report, and request the replacement. Do not load the 22 students and do not drive the bus to warm it up or see whether the warning clears. If the replacement is late, dispatch must arrange coverage or notify the stops. When the replacement arrives, complete a full brake test before descending the 7 percent grade in freezing drizzle.
2. A replacement bus arrives at 6:35 with working brakes and lights. Describe how you will control speed on the 7 percent downgrade with 22 students aboard.
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Before starting down, test the brakes at low speed in a safe area and confirm the low-air warning and parking brake function. Select a lower gear before the grade so engine braking holds the bus back; do not rely on the service brakes continuously. Use snub braking: apply firmly to reduce speed by about 5 to 6 mph, release, and repeat, letting the brakes cool between applications. Keep a large following distance and look through the curve for stopped traffic. If the pedal feels spongy, if the bus accelerates despite the lower gear, or if you smell hot brakes, pull over at the first safe wide spot and stop. With students aboard, the safe choice is to delay the route rather than ride a fading brake down a curve.
3. What must you record and report before leaving the lot, and why does the report matter if no passengers were aboard?
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Record each defect on the driver vehicle inspection report, note that the bus was rejected, and notify dispatch and maintenance in writing. Include the gauge reading at which the low-air warning sounded, the push rod condition, the tire tread depth and position, and the stop arm light failure. Even with no passengers aboard, the report creates the paper trail that prevents the bus from being assigned to another driver, supports repair and warranty work, and shows that you followed the inspection requirement. If the bus later moves, the next driver must know it was placed out of service. Keep a copy or confirmation number and do not clear the defects until maintenance certifies the repairs.