In many countries, official statistics indicate that Heavy GoodsVehicles (HGVs) are overrepresented in fatal accidents. The absolute numbers of annual HGV fatalities are also important incentives for preventive measures. The mass in itself makes HGVs very aggressive when impacting with other road users. For instance, a head-on collision between a fully loaded HGV and an ordinary car, both at 50 km/h, will expose the car occupants to the same velocity change as a barrier collision at almost 100 km/h. So, as long as special deformation zones are missing in HGVs, their active safety is of utmost importance. Experimental studies and theoretical analyses have revealed numerous accident avoidance problems with HGVs, due to their great dimensions and variations in weights. The articulation needed for manoeuvrability at low speed creates stability problems at highway speeds, particularly during braking. This was supported by evidence from a recent case-control study in the U.S. A similar research program was opened during 1986/87 with measurements of decisive quantities in the air brake systems and of the braking characteristics of HGVs in the Nordic countries Denmark, Finland, Norway, and Sweden. In each country 100 HGV-combinations were randomly selected from the normal traffic flow on suitable roads to achieve results representative for the four vehicle populations. Both the overall deceleration performance and the brake force distribution were measured directly by driving and dynamometer tests. Also recorded were weight distributions, brake and wheel size, push rod stroke, load sensing valve amplitude, etc. Wheel lockup observations are related to simultaneous deceleration and control pressure measurements. The deviations between ideal and recorded influence from load sensing devices are evaluated. No Antilock Brake Systems, (ABS), were found in these vehicle samples. (No further information apart from this abstract is published in the proceedings).
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