This report concerns the effectiveness of motorway service areas (MSAs) in reducing road-traffic crashes (RTCs), especially those that are sleep-related crashes (SRCs). It is in three parts: the relationship of fatal and injury RTCs to the location of MSAs, and a survey of why drivers stop at MSAs, followed by a general discusstion. Sections of two motorways (X ¼ 139 km and Y ¼ 87 km) were chosen for their variation in facilities and different inter-MSA distances. Analyses of RTCs were over 2–3 year periods, and were based on detailed police files as these provide more information on RTC causation than STATS19 data. A total of 682 crashes were investigated, of which 181 (26%) were considered to be SRCs. Further analyses were restricted to 16 km either side of 14 MSAs in order to assess whether there was a reduction in RTCs after an MSA compared with the same distance beforehand. Within these 16 km sections, a total of 355 RTCs were prior to the MSAs, and 304 were afterwards. This 14% reduction was not statistically significant. When these RTCs were sub-divided into SRCs and non-SRCs, there were 108 SRCs prior to MSAs and 84 afterwards. This 22% decrease was statistically significant (p,0.05), indicating that MSAs were associated with some crash reduction, but only with this type of RTC as all other non-SRCs showed a nonsignificant 11% drop. Moreover, there were large differences between MSAs in all these respects, with about half the MSAs seeming to have little or no beneficial effect on RTCs or SRCs. The presence or absence of ‘Tiredness Kills – Take a Break’ signs prior to an MSA did not seem to have any specific effects on local RTCs and SRCs. However, the survey indicated that drivers were aware of the signs in general. The distance between adjacent MSAs in relation to this having an effect on the incidence of crashes showed no clear relationship (e.g. SRCs did not necessarily increase with distance apart). RTCs varied by time of day, especially SRCs. The latter is largely due to the human body clock (‘circadian rhythm’), with the greatest incidences of SRCs being 0000–0600h. However, and in general, MSAs seemed to offer no benefit with respect to SRCs during this particularly vulnerable period, which is a matter of concern. Relatively, the greatest reduction in RTCs (especially SRCs) that might be attributed to an MSA involved cars. This was not apparent with goods vehicles (HGV, LGV, MGVand vans) although these vehicles showed some small reduction in SRCs. Seasonally, MSAs seemed to be somewhat more effective in reducing RTCs and SRCs during the autumn and winter. Seasonal changes to weather and daylight must be borne in mind here. Day of week effects were apparent, with MSAs being associated with decreases in RTC and SRC rates on Fridays, Saturdays, Sundays and Mondays, whereas on Thursdays and Tuesdays MSAs seemed to provide little or no benefits in this respect. Our sample was too small to break down the analyses further into, for example, day of week by season, or season by time of day. While facilities at both northbound and southbound sections of individual MSAs are usually very similar, there can be marked differences between the two sides in any effect on RTCs, especially SRCs. This may reflect contrasts between being near to a journey’s end and its beginning. Drivers stopping at MSAs were typically men aged 30 to 60 years, not on businessrelated journeys, and who were driving a car. The low proportion of business-related journeys, here, was in-line with the findings from our focus group. Even when there were car-driving passengers, the burden of driving primarily fell on one person. Men were more likely to drive beyond two hours between stops, as would: drivers on business-related journeys; those driving at night; and those with a high annual mileage. ‘Using the toilet’ was the dominant reason for stopping at an MSA, with 50% of stops being for less than 10 minutes. For most drivers, including those declaring ‘tiredness’ as a reason for stopping, a small cafe´ and/or shop supplying drinks and snacks, along with toilets, would probably be sufficient for their needs. Coffee was the most popular drink purchased, and many drivers acknowledged that they had bought it in order to help stay awake, particularly if they had stopped driving because of tiredness. Nevertheless, there were still many drivers who seemed to be ignorant of this advantage of coffee (caffeine) and of the Highway Code guidelines in this respect. Overall, this study points to a greater need to avoid ‘tired driving’, and that the attractiveness of ‘Taking a Break at an MSA’ requires further attention. (Author/publisher)
Abstract