The introduction of average speed over distance cameras as a road safety tool to reduce excessive speeds and accidents on the roads of the Western Cape, South Africa

Van Velden, Wouter (2017-03)

Thesis (MScEng)--Stellenbosch University, 2017.

Thesis

ENGLISH ABSTRACT: Road safety is a joint responsibility of the road users, design engineers, maintenance teams, law enforcement teams and the various departments within governments that are related to transport and road safety. Road safety has a major impact on society. The number of road accidents is a serious problem in most societies as they impact negatively on many people, either directly or indirectly, as well as on the economy. Concerted efforts are being made to reduce the number of fatalities on the roads. Although there has been an improvement, South Africa still ranks high of the list of countries with the most fatalities on their roads. The World Health Organisation (WHO) listed South Africa as 38th in the world, with 25.1 deaths per 100 000 population in 2013. The Western Cape Government implemented Average-Speed-Over-Distance (ASOD) technology on the roads of the Western Cape in South Africa in an effort to reduce excessive speeding and accidents. ASOD was introduced into the province in 2011 with a pilot project on the R61 route between Beaufort West and the Eastern Cape border towards the town of Aberdeen. Since 2011, another five phases covering a total of 451 km of the Western Cape Province’s most dangerous roads were rolled out. This study evaluated the impact of ASOD on three rural routes, the R27 West Coast Road between Cape Town and Langebaan, the N1 between Touwsriver and Riemhoogte and the N2 over the Sir Lowry’s Pass between Somerset West and Grabouw. The impact of ASOD was evaluated on two levels: excessive speeding (speeds more than 10 km/h above the speed limit, and 85th percentile speeds) and accidents. A time series analysis was conducted on the data obtained from permanent CTO-stations installed across the province. A comparative study on 85th percentile speeds was conducted on industry provided probe data. A numerical analysis was done on the corresponding accident data. A benefit-costs analysis was also conducted on the project. The interrupted time series analysis found that there was an abrupt and permanent reduction in excessive speeds on the R27 route after the implementation of ASOD. The number of vehicles exceeding the 130 km/h mark reduced from 12 292 vehicles to 6 122 within three months, a reduction of 50%. The time series analysis conducted on the N1 did not find any statistical significant reductions in excessive speed due to the implementation of ASOD – neither had there been on the control route The time series analysis found that there was an abrupt and permanent reduction in excessive speeds on the N2 across Sir Lowry’s Pass. Probe data was analysed for the R27 West Coast Road with a 120 km/h speed limit. The study found that the 85th percentile speeds dropped from 125.5 km/h before ASOD implementation to 116.4 km/h post-ASOD implementation. A dataset two years later revealed a 115.2 km/h 85th percentile speed. The probe data analysis confirmed the findings of the time series analysis: there was a significant reduction is speed after the implementation of ASOD. The numerical analysis of the accident data on the R27 West Coast Road concluded that the reduction in the number of accidents after the ASOD implementation was much greater than the theoretical value, as determined by Nilsson’s Power Model. Also, in the year after ASOD implementation, there was not a single fatal accident on the N1 section under investigation. The benefit cost analysis, based on the benefits and costs for the first year of implementation on the N1 between Beaufort West and Riemhoogte, revealed a 2.13:1 ratio. It was therefore concluded that ASOD had made a significant impact on the reduction in the number of excessive speedsters. This finding was supported by the reduction in the number of accidents and injuries. This ultimately played a role in the improvement of road safety in the Western Cape Province, South Africa.

AFRIKAANSE OPSOMMING: Padveiligheid is ‘n gesamentlike verantwoordelikheid tussen padgebruikers, ontwerp ingenieurs, onderhoudspanne, wetstoepassingsbeamptes en verkeie departmente binne die regering. Padveiligheid het ‘n groot impak op die samelewing as ‘n geheel. Die aantal ongelukke en die erns daarvan is ‘n ernstige probleem in vele samelewings, omdat dit ‘n negatiewe impak het op die mense, ongeag direk of indirek, asook die ekonomie. Daar word daadwerklike pogings aangewend om die aantal padsterftes te verminder, veral oor die feesseisoene. Alhoewel daar ‘n verbetering was, rang Suid Afrika steeds in die top van lande met die meeste padsterftes per kapita. Die Wêreld Gesondheidsraad het Suid Afrika as 38ste in die wêreld gelys, met 25.1 sterftes per 100 000 mense in 2013. Die Weskaap Provinsiale Regering het Gemiddelde Spoed Oor Afstand tegnologie op die paaie van die Weskaap ingespan. Die projek het ten doel gehad om oormatige spoed en daarmee saam ongelukke te verminder. Die projek is in 2011 geloots op die R61 tussen Beaufort Wes en die Oos-Kaap se grens, oppad na Aberdeen. Intussen is daar vyf fases uitgerol regoor die Weskaap Provinsie. Die studie het die impak van die tegnologie op drie landelike roetes analiseer. Hierdie roetes is die R27 tussen Kaapstad en Langebaan, die N1 tussen Touwsrivier en Riemhoogte en die N2 oor die Sir Lowry’s pas tussen Somerset-wes en Grabouw. The impak van die tegnologie is op twee vlakke geanaliseer, naamlik oormatige spoed (spoed meer as 10 km/h oor die spoed grens, en 85ste persentiel spoed) en ongelukke. ‘n Tydreeks analise is gedoen op die data soos opgeneem deur telstasies op verskeie plekke binne die provinsie. ‘n Vergelykende studie op 85ste persentiel spoed is gedoen op intydse data. ‘n Numeriese analise van die ongeluksdata is gedoen, asook ‘n voordeel-koste analise op die projek as ‘n geheel. Die tydreeksanalises het getoon dat daar op beide die R27 en N2 ‘n skielike en permanente verandering was in die spoed op die roetes. Daar kon wel nie ‘n statistiese beduidende verandering op die N1 waargeneem word nie. Die “Probe data” was geanaliseer op die R27 Weskuspad met ‘n 120 km/h spoedgrens. Die studie het gevind dat die 85ste persentiel spoed van 125.5 km/h voor die implementering van gemiddelde spoed oor afstand kameras, gedaal het na 116.4 km/h. ‘n Datastel twee jaar later se analise het getoon dat die 85ste persentiel spoed nog verder gedaal het na 115.2 km/h. Die “probe data” analise het dus die bevindinge van die tydreeksanalise bevestig: daar was ‘n beduidende vermindering in spoed sedert die implementering van die gemiddelde spoed oor afstand kameras. Die numeriese analise van die ongeluksdata op die R27 het wel getoon dat die vermindering in ongelukke na die implementering van die projek, veel meer was as die teoretiese-berekende waarde. Daar was in die jaar na die implementering nie een enkele noodlottige ongeluk nie. Die voordeel-koste analise op die N1 tussen Beaufort Wes en Riemhoogte het ‘n verhouding van 2.13 tot 1 getoon, gebasseer op die voordele en die kostes in die eerste jaar van die projek na implementering. Die studie het dus bevind dat gemiddelde spoed oor afstand kameras ‘n beduidende impak gehad het op die hoeveelheid oormatige spoed oortredings, tesame met ‘n vermindering teweeggebring in die aantal ernstige ongelukke. Dit het meegebring dat daar ‘n verbetering in die padveiligheid situasie binne die Weskaap Provinsie in Suid Afrika is.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/101108
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