SCHOOL BUS SEAT BELTS

THEIR FITMENT, EFFECTIVENESS AND COST  

(Contents listing and executive summary only)    

Prepared for the (former) Bus Safety Advisory Committee, New South Wales Department of Transport

December 1994  
by  
MICHAEL HENDERSON and MICHAEL PAINE

 Dr Michael Henderson is a medical graduate who has spent over 25 years in road safety and injury control, and was the first director of the Traffic Accident Research Unit. He now works as a health and safety researcher and consultant, with special interest in the control of traffic injury. During 1993 he managed for the Child Accident Prevention Foundation of Australia a crash-investigation study of children as the occupants of motor vehicles. He is a Board member of the Association for the Advancement of Automotive Medicine (AAAM). [now retired]
    
Mr Michael Paine is Manager, Vehicle Design and Research Pty Ltd. He has had over 17 years professional experience in the development and implementation of vehicle construction and inspection policies. Previously a senior engineering manager with the Roads and Traffic Authority of NSW, he established strong ties with representatives of the NSW bus industry through his work on the Heavy Vehicle Consultative Committee and the development of various heavy vehicle construction standards. As consultant to the Road Safety Bureau's School Bus Safety Task Force, he contributed to a study on the safety of school children near buses and other safety issues related to school buses.
 

Updates

(all updates are by Michael Paine and are his views only)

28 May 12: Bus Seat Belts in Australia - Presentation at Automotive Safety Week, Melaka Malaysia, 22-23 May 2012.

14 Mar 12 BBC: Switzerland bus crash kills 28, including 22 children

Comment: Based on the limited information that is available, this appears to be a crash where Australian ADR68 seats (integral 3 point seat belts tested at 20g) would have prevented many of the fatalities. It has some of the characteristics of the 1989 Kempsey bus crash that triggered unilateral action on bus safety in Australia.

ESV05 paper: THREE POINT SEAT BELTS ON COACHES - THE FIRST DECADE IN AUSTRALIA 

Extracts

"On-scene reviews by federal and state vehicle safety experts concluded that a regulation based on ECE 80 would not have been effective in these crashes. Initial calculations indicated that nothing less than three point seat belts with a 20g crash force capability would offer adequate protection. This led to the development of Australian Design Rule 68 (ADR 68) which became mandatory for all Australian coaches built from July 1994...bus manufacturers and operators were critical of the proposed ADR and cited cost and weight penalties inherent in the package (FORS 1992). More than a decade later it is evident that those initial concerns were unfounded and acceptance of this rule by government, industry and road users is reportedly high...Surprisingly, this Australian initiative has not been widely adopted internationally. Some researchers and regulators continue to debate the technical feasibility and consumer acceptance of three point seat belts on coaches, despite the use of such systems in Australia for more than 10 years..." 

"Initial concerns about the cost and weight of seats fitted with three point seat belts have proved to be unfounded. The breakthrough was to abandon traditional seat designs and to develop new seats using modern engineering design tools. The resulting seats, fitted with seat belts, are no heavier (actually lighter in some cases) and not significantly more expensive than their predecessors. The importance of this outcome should not be underestimated - the potential benefits of seat belt restrained coach occupants has been achieved without increasing the cost of coach travel in Australia..."

Left: Kempsey bus crash wrecks - the basis for ADR68. 36 fatalities when two coaches collided head-on on a 100km/h road.

Right: Swiss bus crash March 2012


Buses involved in Kempsey crashswiss_bus_crash

Video of early tests of 20g seat belt systems

Other major crashes

Update - August 2007

There are fresh calls for seat belts to be fitted to school buses in Australia. While there are good arguments to require that children only travel by road with seat belts, many of the conclusions from the 1994 research are still applicable.

In a project conducted in 2005 for the National Transport Commission  it was found that nothing short of full ADR68  seat with integrated 3 point seat belts (capable of 20g decelerations) would be likely to save lives in a severe bus accident (see page 6). Stop-gap methods such as fitting lap seat belts to old buses could exacerbate injuries.

There have been recent developments that make the fitting of seat belts more attractive:3 for 2 bus seats Despite these developments, it is still likely that there are much more effective ways to improve the safety of school travel. It may be time to revisit the 1994 study.

More cost-effective priorities for bus safety equipment:
  1. School buses in all Australian mainland states need the bright halogen flashing lights, FRONT and rear, as used in Tasmania and the USA. See my 1996 ESV paper co-authored with Dr Alec Fisher. Unfortunately the NSW RTA still allows aftermarket wig-wag lights with poor signal range (TS142).  These have less than 50m signal range on a bright day!
  2. Dual circuit braking systems. Incredibly there are likely to be some ancient school buses in operation that have single circuit braking systems. These were banned from new trucks and buses in the 1970s.
  3. Padded handrails and stanchions (page 19
  4. Improved emergency exits and signage (page 11)
  5. Thorough structural inspection by a professional engineer, including removal of some body and floor panels (page 15)
Behavioural and road environment countermeasures are also available.

NTC Oct 2007:  Seatbelt retrofit Code for safer buses - A voluntary guideline will protect bus owners and the public against sub-standard seatbelt retrofit practices. See also this report on retrofitting seat belts to buses.

Oct 1989: Michael Paine and Rodney Vaughan attended the scene of the Grafton bus crash to conduct preliminary investigations of vehicle factors that led to 18 bus occupant fatalities and to provide on-scene advice to government ministers.

     

CONTENTS
 
 

EXECUTIVE SUMMARY i

1 INTRODUCTION 1

1.1 Background 1

1.2 Brief for present project 1

1.3 Procedure 2

1.4 Definitions 3

2 PREVIOUS REVIEWS AND STUDIES OF SCHOOL BUS

SAFETY IN AUSTRALIA 5

3 SCHOOL BUSES IN NEW SOUTH WALES 8

3.1 The transport of school children 8

3.2 Types of bus used for school transport 10

3.3 Applicable safety standards 11

3.3.1 NSW Motor Traffic Regulations and Public Vehicle Regulations 11

3.3.2 Australian Design Rules for commercial vehicles 12

3.3.3 Other relevant Australian Design Rules 14

3.3.4 Summary of present rules for seat belts in school buses 15

4 ANALYSIS OF SCHOOL BUS ACCIDENTS AND THE

EFFECTIVENESS OF SEAT BELTS 16

4.1 Accident analysis 16

4.2 Principles of in-crash protection 16

4.3 School bus accident data in New South Wales, 1989-1992 18

4.4 School bus accident data in the United States 25

4.5 Seat belts as part of the system of protection 29

4.6 Seat belt effectiveness in passenger cars 30

4.6.1 Statistical studies 30

4.6.2 Injuries caused by seat belts 32

4.6.3 Summary of data on seat-belt effectiveness in passenger cars 33

4.7 Seat belt effectiveness in buses 34

4.7.1 Test crashes on school buses 34

4.7.2 Sled tests of school bus lap belts 38

4.7.3 Summary of data on seat-belt effectiveness on buses 38

4.8 Estimations of compliance with regulations on seat belt use in

school buses 40

5 THE DEBATE ON SCHOOL BUS SEAT BELTS IN NORTH AMERICA AND BRITAIN 42

5.1 History and situation in the United States and Canada 42

5.2 US Federal Motor Vehicle Safety Standards for school buses 45

5.3 United Kingdom requirements 48

6 THE INSTALLATION OF SEAT BELTS IN NSW BUSES 49

6.1 The NSW bus fleet 49

6.2 Construction techniques for route service buses 51

6.3 Examination of representative buses 53

6.3.1 Non-government buses 53

6.3.2 Government buses 54

6.4 Anchorage positions 55

7 OTHER BUS CRASH SAFETY FEATURES 56

7.1 Padding for bus interiors 56

7.2 Alternatives to seat belts 57

7.3 Rearward facing seats 57

7.4 Seat back height 58

8 OPTIONS FOR UPGRADING BUS SAFETY 60

8.1 Options for number, position and types of seat belt 60

8.1.1 Floor-mounted, lap-only seat belts 60

8.1.2 The ADR 66 approach 61

8.1.3 The ADR 68 approach 61

8.2 Safety modifications to buses 62

8.2.1 Retrofitting existing buses 62

8.2.2 Fitment to new buses 63

9 COST EFFECTIVENESS ESTIMATIONS 66

9.1 The cost of crashes 66

9.2 Costs and effectiveness of safety features 66

9.3 Associated costs 67

9.4 General transport issues 68

9.5 Summary of costs of seat-belt fitment 69

10 DISCUSSION 70

10.1 The case for seat belts in buses 70

10.2 The case against seat belts in buses 72

11 CONCLUSIONS AND RECOMMENDATIONS 75

11.1 Large buses 75

11.2 Small buses 76

11.3 General measures 78

12 REFERENCES 79
 
 
 
 

EXECUTIVE SUMMARY
 
 
 
 
 
 
 
 

1 Background
 
The safety measure examined in this report is the fitment and use of seat belts in school buses. The project arose from a request by the Minister for Transport in New South Wales to the Bus and Coach Safety Standing Committee.

The use of seat belts is a widely-accepted, effective safety measure in passenger cars, and many parents and safety advocates simply cannot understand how it is that if seat belts promise such benefits to car occupants, then these benefits are not offered to passengers on buses taking children to school. The report therefore addresses the construction and use of school buses, the rules governing their construction and the fitting of seat belts, NSW data relating to school bus accidents, the potential effectiveness of seat belts in buses, and the costs and effectiveness of various related options.

There is no all-embracing definition of a "school bus". Numerically, most children in NSW are carried in "route service" or "transit" buses, the type of bus typically used in urban areas. The main difference between the United States and New South Wales is that in America a school bus is a specific type of vehicle. This is why many of the constructional and safety features used in the United States could not simply be applied to buses used for school transport in this country.

There have been several previous studies in Australia that have considered bus safety, including the fitting of seat belts. The consensus of expert opinion has always been that the accident rate among bus passengers is so low, and the benefits of seat belts so doubtful, that the expense of fitting belts cannot be justified. However, it has been concluded that seat belts should be fitted in newly built inter-urban coaches, in conjunction with well-padded and high-backed seats. This has resulted in the implementation of appropriate Australian Design Rules (ADRs).

Just over one million students attend primary and secondary schools in New South Wales. Of these, 659,182 (64%) were provided with free or subsidised travel under the School Students Transport Scheme (SSTS) in 1991/92. The others make their own arrangements (by walking, bicycle or car), or have access to a 50% concessional fare on government or some private transport. The total number of students travelling to school each day by some kind of bus is estimated to be just over 600,000. The total distance travelled (two-way) is estimated to be 7.7 million km per day or 1.5 billion km per year (201 school days in a year). In New South Wales, while very few buses are used exclusively (as in north America) for the transport of school children, from time to time nearly all buses are used for the purpose.

No special safety standards or specifications apply specifically to "school buses". All buses must comply with the relevant ADRs, but these have no special provisions for "school" buses.

The only buses used to transport school children that are required to have seat belts in all seating positions are those with 12 or fewer seats manufactured on or after 1 July 1983. Very few, if any "school" buses are directly affected by the improved occupant protection applying to coaches under ADRs 66 and 68, because these "long distance" coaches are very rarely used for day-to-day transport of school children.

2 Accident analysis
 
In order to study NSW school bus accidents in more detail, individual examinations were made of all police accident reports that reported accidents occurring during school travel time in which a child aged between 5 years and 18 years was killed or injured as a passenger in a bus. The four calendar years 1989 to 1992 were examined. Under these criteria, 37 accidents were identified, in which 121 children were injured and one was killed. Findings included the following: • bus crashes in school travel hours involving injury to child passengers are exceedingly rare in New South Wales;

• official figures overestimate the figure for child bus occupant casualties by about 40%;

• 97.5% of the reported injuries were "minor", including shock and trivial bruises;

• the commonest injuries were to the face, head and neck, and these most commonly occurred in frontal collisions, probably as a result of contact with the seat in front of the occupant.
 
 

American studies have also shown that the overwhelming cause of injury in a school bus collision is the seat. In most US school buses made before 1977 there was exposed steel tubing on the tops of seat backs, and the backs of the seats were unpadded. It was concluded that the use of lap belts alone in conjunction with the low-backed and inadequately padded seats that were typical of those installed in school buses in North America at that time (and are still typical of route service buses in New South Wales) could increase injury because the lap belted passenger pivots about the belt and slams the head, face and, if tall enough, chest into the seat back ahead. Following new American rules on padding, and on seat backs that absorb impact, lap belts became acceptable but still not mandatory. The present position of American authorities is that there are other school bus safety measures that would provide greater safety benefits for the money spent than passenger seat belts. 3 Seat belt effectiveness
 
Post-1977 American buses are especially designed to minimise injuries to the upper part of the body. Australian route service buses are built with no such consideration. Accordingly, not even the small benefit in frontal crashes that has been calculated could flow from the installation of seat belts in American school buses could be accrued in New South Wales. Any benefit would flow only from reduction in injuries from rollover and, possibly, from severe side impact. Both types of crash are exceedingly rare in large route service buses. The use of lap belts in these buses, in the absence of modifications to the seats, could well increase the risk of injury in frontal impacts, which - although rare - are much more common than rollovers. In addition, lap belts threaten belt-induced internal injury to children, to an extent not shared by lap/sash belts.

The fitment of lap/sash belts to route service buses could decrease the risk of injury to passengers. The extent of this reduction is not known, but would be unlikely to exceed 20% even if - as would be essential - the belts were worn at all times.

The effectiveness of lap belts in small buses depends on the kind of seats fitted. In many small buses the seat backs are high and quite well padded, and the situation is akin to that faced by a rear-seat passenger in a car. It is reasonable, therefore, to predict a reduction of up to 20% in the risk of death or injury from the fitment and use of a lap belt in a small bus. Where lap/sash belts can be fitted to small buses, their overall effectiveness might be predicted to be in the order of 30% to 40%, based on related literature on passenger cars.

Lap/sash seat belts are used in the smallest of buses, those that go near to complying with ADRs for passenger cars and which are often known as "people-movers". In these vehicles, the effectiveness of the lap/sash belts would be of the same order as in a conventional car, around 50%.

The overall effectiveness of seat belts, whether in cars or buses, depends on the use that is made of them. It is imperative, in any case, that where seat belts are used by some occupants, they are used by all. This is because an unrestrained occupant can cause injury to other occupants who are restrained. In addition, the stiffer seats that would be required for mounting sash belts would cause more injury to unrestrained occupants than the more compliant seats that now have no such mountings.

Because of the high use rate of seat belts in passenger cars in Australia, it is likely that there would be a generally favourable response by student bus passengers to requirements that seat belts should be used, and a compliance rate of at least 80% should be attainable with minimal supervision. This forecast, of course, would apply only to school buses dedicated to the purpose of school transportation, as in the United States. However, in Australia most children are not carried in dedicated school buses, but in buses that also carry other passengers.

Passengers in conventional route buses may find seat belt installations to be inconvenient, and passengers making short trips may not take the time to fasten seat belts especially if they are carrying parcels. Passengers sitting in aisle seats would find it inconvenient to unbuckle seat belts to allow passengers in and out of window seats. The belts themselves would almost certainly be retractable, but in the unlikely event that they were not, they would become dirty from dangling on the floor and this would discourage their use. School children travelling on such buses would be relatively unlikely to use seat belts.

4 Increasing the safety of buses

4.1 Seat belts
 
 

There are three main options relating to the fitment of seat belts in buses used for student transport, or for the provision of equivalent protection. The following options have been used as a basis for assessment of the fitment of seat belts to new and existing buses. • Fit floor-mounted lap-only seat belts to provide some restraint for occupants, but not necessarily protection in a severe crash. Some buses used for transporting handicapped children have seat belts for this purpose.

• The ADR 66 approach: design seats to cushion the impact of occupants striking them from the rear; provide seat belts (or equivalent protection) for "unprotected" seats; design for crash deceleration of about 12 g.

• The ADR 68 approach: design seats with integral seat belts which withstand a crash deceleration of about 20 g.
 
 

There are numerous technical difficulties with retrofitting seat belts. A major obstacle is that the seats and underfloor structure of many urban route buses are unsuitable for seat belt loadings. Even floor-mounted lap-only seat belts would be difficult to fit to most buses due to the need to strengthen the underfloor structure, and sometimes where the structure is strong it is in the wrong place for seat belt anchorages. Many underfloor areas are inaccessible because of the close proximity of the engine, fuel tank and luggage bins.

There is no point in installing seat belts in existing buses if this is not done in conjunction with other measures to reduce the risk of injury to occupants. In particular, seat design, padding and seat anchoring needs to be suitable. Therefore, there is a progression of safety improvements which might be considered, with the most effective (and most expensive) option being the installation of integral three-point lap/sash seat belts, complete with locking retractors.

Seat belts in route service buses, if indeed they add any protection for passengers at all, are far less effective than in passenger cars. Test crashes have shown that the risk of increasing injury for some passengers if a lap belt only is used exists even when seats are padded. Route service buses in New South Wales do not have adequately padded seats, and researchers and advocates of lap belts for buses in the United States have specifically advised against fitting lap belts when the seats are unpadded and topped by steel bars, as is typical in New South Wales.

Accordingly, the only effective seat belts for student transport would be three-point, lap/sash seat belts integrated in seats, as for long-distance coaches. The practical difficulties and costs of fitting such restraint systems in route service buses would be very high. Indeed, the practical difficulties of retrofitting seat belts to existing buses are so severe that even the strongest proponents of seat belts for school buses in the United States do not support the measure.

The direct costs of fitting seat belts in new large buses are a matter for estimation, and estimates from industry sources are about twice as high as from safety advocates. In today's terms, the marginal costs for fitting lap-only seat belts on a new bus should not exceed $5,000. The cost of fitting a new set of seats is in the order of $30,000, and the marginal cost of fitting those seats with three-point seat belts would be in the order of $12,000 to $15,000. There could be other associated costs, including improvements in the crashworthiness of interiors through, for example, padding.

The total cost for retrofitting the fleet with effective three-point, lap/sash restraint systems would be over a hundred million dollars and could - according to industry estimates - exceed two hundred million..

Additional costs would arise from contingent changes to regulations allowing three-for-two seating, and on standing passengers. These would reduce bus capacity, increase the possibility that students would use other forms of travel carrying a higher risk than bus transport, and increase the number of buses on the roads. The total cost per student life saved could be in the order of half a billion dollars.

Small buses in Australia, as typically used for school transport, generally have seat designs that would be suitable for relatively inexpensive, floor-mounted, lap belts. Small buses with high-backed seats would provide safer transport if seat belts were fitted.

Because of the very low rate of crash involvement of small buses in New South Wales, mandatory retrofitting of neither lap belts nor lap/sash belts is recommended.

However, it is common for groups that run and supervise the operation of small buses used for school transport to seek guidance on the voluntary fitting of seat belts, customarily at the owner/operators' expense, with user reimbursement where appropriate. On safety grounds, these consultants see no reason to discourage such fitment. Indeed, it is considered that such fitment should be encouraged and, subject to the recommendation that follows, the benefits publicised.

But those who set out to fit belts in small buses have at present no official source of information to which to turn. An officially-sanctioned code of practice will be of great assistance in ensuring that when seat belts are fitted voluntarily, this is done properly. It will also prevent the fitment of unsuitable seat belts, or seat belts to unsuitable vehicles. Such a scheme could be monitored and overseen with the assistance of the existing scheme for the fitting of child restraints. The draft National Code of Practice for Improving Occupant Protection in Existing Buses will, when finalised, be of great benefit in this regard.

This investigation highlighted a loophole in the existing set of Australian Design Rules which cover seat belts in buses and coaches. Very small buses, including large passenger cars known as "people-movers", have to have seat belts for all seats, with lap/sash belts for the outboard seats. This applies up to a seating capacity of 13. For vehicles of up to 3.5 tonnes GVM with a seating capacity of 13 to 16, seat belts are only required for "non-protected" seating positions (that is, with no seat or other structure in front). Thus, in some small buses the driver has a seat belt but most passengers do not.

4.2 Other measures
 
Most injuries in large buses are minor ones to the face and head, resulting from contact with the tops of the seat backs. These injuries could be prevented comparatively easily, and at much lower expense than fitting seat belts, by modifications to the tops of the seats. Given the existence of vertical stanchions for standing passengers, there would appear to be small need for the injurious steel rail that is fixed across the tops of the typical route service bus seat. Removing this rail, replacing it with a yielding structure, or covering it with padding, are all measures that would decrease minor injuries to both children and adults.

The vast majority of students who are hurt while using school bus transport have been alighting from or entering the bus, hanging on to the outside, trapped in the door, or walking in the vicinity of the bus. Public expenditure on improving the safety of student travel would be much better directed at these other causes for injury, and the chance of a valuable return in injury reduction would be much higher than in fitting seat belts for occupants.

Recommendations

The following recommendations are made in this report:

Recommendation 1: the mandatory fitting of lap-only or lap/sash seat belts in large route service buses used for the transport of children in the School Student Transport Scheme is not recommended;

Recommendation 2: that the metro style seat typically used in route service buses be redesigned so as to ensure that handholds are constructed of impact-absorbing material, or where rails are not used, to replace unyielding seat tops with shock-absorbing material such as padding; and that new seats be fitted to replacement buses as they come into service;

Recommendation 3: that a program of research be undertaken to develop specifications for padding for bus seats and stanchions, and that meanwhile a program for retrofitment to existing buses be drawn up;

Recommendation 4: that the draft National Code of Practice for Improving Occupant Protection in Existing Buses be encouraged and its finalisation expedited, particularly in regard to the fitment of seat belts to new and existing small buses.

Recommendation 5: that no provision of the Australian Design Rules should have the effect that small buses with less than 17 seats should be exempt from any requirements for fitting seat belts for all seating positions;

Recommendation 6: that existing reviews of pedestrian safety take into full account the passenger who is leaving or boarding a bus, and that studies be undertaken of warning and interlock measures that will ensure that doors are properly closed and the bus cannot move if there is an obstruction at the edge of any door that is out of the direct line of sight of the driver.
 
 

Road safety links.

More links on bus seat belts: