• Accident Prevention
• Retarders
• Crashworthiness
• Bus Passenger Protection
• Transport Canada Program – Bus Safety – General

Accident Prevention

Bus safety depends on roads, vehicles and drivers much as for any other vehicle. Recent major bus accidents involve questions of familiar accident factors such as brake maintenance and driver fatigue, in common with other commercial vehicles. Buses and their operators abide by and benefit from common road safety rules. Motor Vehicle Safety Regulations and the National Safety Code treat buses the same as other vehicles of comparable size except for specific standards aimed at bus passenger protection and the protection of children around school buses.

The Motor Vehicle Safety Regulations apply "crash avoidance" standards to buses. Of major significance is the recent updating of the air brake standard CMVSS 121 to require automatic slack adjusters, which are designed to reduce the demands on careful brake maintenance. Of similar major significance, air-braked vehicles will shortly be required to have anti-skid brake systems (ABS).

The National Safety Code similarly applies its vehicle inspection and maintenance standards and its driver qualifications, training, log book and hours of service requirements to buses. Safety fitness is key to the National Safety Code and, under a new safety rating standard and data exchange program, motor carriers will be closely monitored for safe performance wherever they operate.

There is no reason to suggest that buses should be treated differently from other vehicles for the purpose of accident prevention. This report, therefore, does not identify or examine accident prevention issues that are common to other classes of vehicle. The one exception is that retarders have been identified as possible mitigating devices in bus crashes involving hilly terrain.

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Retarders

Four fundamental types of retarder are all supplementary devices providing retarding force through the driveline, up to 10% of foundation brake force¹. One controls the engine exhaust valves and one restricts exhaust flow, both enhancing engine braking by harnessing piston pumping action. The other two are effectively supplementary brakes in the driveline, hydraulic or electric².

Retarders reduce the use of foundation brakes and therefore, at some capital and operating cost (maintenance and loss of payload), reduce brake maintenance. Correctly used they ease the driver’s task. They are therefore marketable and widely installed on buses and other commercial vehicles.

Retarders, properly used, provide a significant slowing force, an extra redundancy in the overall brake system. They could help to prevent downhill runaways in certain circumstances. Braking problems on steep hills were determined as contributing factors in two very serious fatal bus crashes³. Retarders, had they been installed and correctly used, could have helped to control the descent.

Retarders are, however, not substitutes for adequately designed and well-maintained foundation brakes. Adequate foundation brakes are essential for safety and are designed to stop or slow a vehicle under any reasonable conditions of use. Regulations for new vehicle brakes and for brake maintenance set out to ensure that this is practice.

Regulations go a long way towards ensuring adequate foundation brake systems. Recent standards addressing automatic slack adjusters and ABS should provide for further progress in overall braking performance. Brake maintenance is an issue in audit, inspection and maintenance procedures under the National Safety Code and programs currently under way should help to ensure continuing improvement.

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Crashworthiness

As with the 100 series crash avoidance standards, most of the Motor Vehicle Safety Regulations 200 and 300 series crashworthiness standards are applicable to buses as to all vehicles of a given weight category. There are, in addition, clearly dedicated bus standards, mostly for school buses.

Buses differ from other road vehicles in their specific role of commercially transporting passengers. This brings special operator responsibility towards passenger safety. In the ten years 1987 to 1996 there were 54 passenger deaths and 12,500 passenger injuries⁴.

This compares with 496 fatalities and 37,000 injuries among all vehicles and pedestrians in crashes involving buses over the ten years⁴. Bus passengers represent 11% of fatalities, bus drivers 2%, pedestrians 25% and the majority of the remaining 62% are drivers or passengers in other involved vehicles⁴.

Not surprisingly protection of drivers and passengers in light vehicles in the event of crashes with large vehicles has been and remains a key road safety issue. It is currently addressed with seat belts, air bags and other complex crash deployment devices. Bus passenger protection is a separate issue with different perspectives.

Buses provide passengers with remarkably safe travel compared with other road vehicles and other modes of transport. The objective is, however, that buses provide the best possible safety, not just comparatively very safe travel. This makes bus passenger protection a subject on its own.

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Bus Passenger Protection

Table 2: 1996 Canadian Bus Industry Information⁵

Bus passenger protection involves the bus operating industry and the operating environment as much as it involves vehicle design and vehicle standards. As would be expected from the numbers in Table 2, school buses attract much of the attention. Intercity and charter buses, although well recognized when seen, are relatively unobtrusive in vehicle and road statistics.

Buses other than school buses are more difficult to differentiate reliably. Canadian and U.S. federal safety standards define them collectively. In considering specific standards, however, it is necessary to recognize special design for specific operation. City buses, for example, are often designed to operate with standee passengers, recognized in an ECE definition "city bus". The U.S. EPA also defined urban buses for the purpose of special emission regulations, which were temporarily applied⁶ in the early 1990s.

The following sections separately address "Passenger Protection in Buses other than School Buses" (transit, intercity, transfer, charter and private) and "School bus Passenger Protection".

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Transport Canada Program – Bus Safety – General

1. Transport Canada develops and enforces Canada Motor Vehicle Safety Standards for new buses under the Motor Vehicle Safety Act.
2. Through the Canadian Council of Motor Transport Administrators, Transport Canada supports development and enforcement of the National Safety Code for Motor Carriers.
3. Transport Canada reports on motor carrier safety under the federal Motor Vehicle Transport Act.
4. Transport Canada defect investigators identify safety defects and take steps with manufacturers to correct defects through the Motor Vehicle Safety Act Notice of Defect provisions.
5. Bus operator associations participate in regular National Public Safety Organizations consultation meetings with Transport Canada.

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• Accident Prevention
• Retarders
• Crashworthiness
• Bus Passenger Protection
• Transport Canada Program – Bus Safety – General

Footnotes

1. NHTSA "Retarders for Heavy Vehicles: Evaluation of Performance Characteristics and In-service Costs – Volume 1: Technical Report" February 1981.

2. CCJ/The Air Brake Book "Retarders: Giving Brakes a Break"

3. Transport Canada collision investigation reports.

4. Extract from TRAID, November 1998

5. Statistics Canada "Passenger Bus and Urban Transit Statistics" 53-215-XPB 1996. The industry review involves companies with over $200,000 revenue.

6. Code of Federal Regulations 40CFR Chapter 1, 86.091-2

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