5. Analyses and findings in Road related factors
5.2 Introduction to the analysis of the Road type and Junction type
junction types intersected while travelling on the road on a daily basis, as parts of the considerable contributors to the occurrence of accidents in the Stellenbosch area. However, it is understood that more than one junction or intersection are encountered along the roadways in Stellenbosch. Therefore, estimation of the effect of the road and junction layouts on the road users should be carried out regularly. The results obtained in the analysis of the two data fields establishes a relationship relating the two data fields together with regard to occurrence of road traffic casualties.
5.2.1 Analysis of the Road type
Road type consist of eight variables, which are defined according to the categories of the roadways in the Stellenbosch locality where accidents actually occurred. The first of the eight variables is Freeway, followed by other variables like On/off ramp, Dual carriageway, Single
carriageway, One way, and three other remaining variables such as Other, On-road parking/rank, and Off-road parking/rank. The data points assembled in the table set below
demonstrate close scores between the ‘dual carriageway’ and ‘single carriageway’. According to the table displayed in this section, only dual carriageway and single carriageway generated 82.8% of the total percentage estimates calculated in Road type, while the remaining proportion constitutes the six other variables as demonstrated in the Figure 30.
As graphically illustrated in the chart below, estimated proportions of 42.0% [675] and 41.0% [662] road accidents occurred on both the dual-and single-carriageways respectively, within a high-speed limit of 60km/hr, depending on the location of the accidents. Among the remaining variables, it is observed that an estimated proportion of 5.0% [87] road accidents occurred on
Off-road parking/rank, followed by Freeway with the road accident estimate of 5.0% [83].
Observably, the result realised from the analysis of the Freeway demonstrates that fewer accidents occurred along the traffic with specified speed limits greater than 60km/hr.
Table 17: Road type estimates in road accident occurrence
Total estimates of road accident occurrence on specified Road type in 2012 Months Freeway On/Off
Ramp Dual Carriageway Single Carriageway One Way Other On-road Parking/ Rank Off-road Parking/ Rank Jan 5 0 23 50 2 4 6 6 Feb 10 0 46 60 3 3 3 5 Mar 14 1 81 62 4 4 4 9 Apr 10 1 53 49 2 3 4 7 May 7 1 44 57 3 0 1 5 Jun 8 0 55 39 4 1 1 4 Jul 9 2 26 37 3 1 2 6 Aug 4 0 76 52 5 2 5 8 Sep 6 1 49 64 1 1 2 4 Oct 2 3 95 65 5 2 8 12 Nov 4 0 83 72 1 1 4 11 Dec 4 0 44 55 2 0 3 10 Total scores 83 9 675 662 35 22 43 87
Figure 30: Total estimates of Road type in 2012
It is understood that speed limit is proportional to change or reduction along the dual and single
carriageways while approaching the built-up areas to ensure safety for all the road users, from
a higher speed limit to a lower speed limit (Langford & O’Hare 2005). Despite the implementation of the speed limit cautionary signs along the road sides, however, more accidents occurred everyday along the two road types mentioned above in the Stellenbosch locality. The suggested factors responsible for such large number of casualties along these two road types are identified as:
Violation of specified speed limits along the road,
Poor observation of the speed limit cautionary signs along the roadsides, Influence of alcohol and drugs used by the driver while driving,
Lack of adequate speed detecting devices along the busy roads (Njord et al. 2005), Lack of sufficient quality data to support adequate distribution of the road safety
resources (O’ Day 1993; Vogel & Bester 2004), and
Lack of commitments from the authorised officers in charge of cautioning the behaviours of the road users along these roads.
5.2.2 Analysis of the Junction type
Junction type consist of 12 related variables, which are considered as part of the probable contributors of road casualties within the Stellenbosch area. It is observed that not all junctions are controlled in the Stellenbosch locality. Some junctions are automatically or manually23 controlled by the robots or road signs, depending on how busy the intersections could be during intense traffic activities around the locality. Most road types with controlled junctions are commonly located in the main roads, such as the dual and single carriageways, while other roads like one-way have their junctions controlled mostly by a stop sign. This suggests that the risk posed by the uncontrolled junctions are higher than any other type of controlled junctions within the locality. This effect could increase the amount of road casualties occurring at the uncontrolled intersections (Sinclair & Murdoch 2012).
During personal communications, a high-ranking traffic officer, added that most junction types without a control robot are controlled by the implementation of the stop signs. In addition, the officer further emphasised that car drivers and motorcyclists are advised to cautiously observe the stop signs to avoid road traffic casualties. The stop sign regulates traffic based on a real- time process depending exclusively on the behaviours of the drivers or motorcyclists while arriving at the intersection point. It authorises the first arriving vehicle at the intersection, to depart ahead of the other vehicles in the same queue, in the order of a sequential structure to avoid any accident. In the context of the traffic regulatory sign, the safety of the pedestrians is also considered by implementing the pedestrian crossing signs. More in-depth details are provided in the Appendix C-C.2.1, where the analysis carried out demonstrates the contribution
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Table 18: Junction type estimates in road accident occurrence
Estimates of road accident occurrence at Junction type in 2012 Months Cross Roads T- junction Staggered Junction Y- junction Circle Level Crossing Not a junction or crossing On ramp/slipway Off ramp/slipway Pedestrian Crossing Property Driveway/ Access Other Jan 12 10 3 2 1 0 20 0 0 0 2 9 Feb 23 9 4 2 4 0 32 0 0 3 2 5 Mar 29 8 4 0 5 0 72 0 0 0 2 9 Apr 31 4 3 0 1 1 58 2 0 0 0 5 May 26 12 2 0 3 0 49 0 0 1 3 1 Jun 21 6 6 1 6 0 45 0 0 0 0 0 Jul 17 4 4 0 5 0 20 0 1 0 2 4 Aug 21 3 4 2 5 4 74 0 0 0 1 2 Sep 27 8 2 0 7 0 46 0 0 0 3 2 Oct 29 27 7 0 7 0 85 0 1 0 1 6 Nov 31 18 8 0 6 0 88 0 0 1 2 3 Dec 22 14 4 0 2 0 41 0 0 1 0 5 Total scores 289 123 51 7 52 5 630 2 2 6 18 51
of Traffic control type and other related data fields in the road traffic casualties.
From the Table 18, an estimated proportion of 51.0% [630] road accidents occurred at the locations that are neither junctions nor crossing. This estimate is more than the estimated proportion actualised in Crossroads, with a percentage difference of 27.8% as similarly displayed in Figure 31. The result presented with regard to the Not a junction or crossing,
Figure 31: Total estimates of Junction type in 2012
insinuates that most accidents occurred at a point where the vehicle is not approaching any intersections or crossways along the roads in the Stellenbosch locality. In addition, a total proportion of 10.0% [123] road accidents occurred at the T-junction, which is far above the sum estimate of road accidents that occurred at both Staggered junction, Y-junction and Circle. This result is attributed to three main factors, which are driver’s actions, characteristics of red-light runners, and conditions leading to red-light running (Sinclair & Murdoch 2012).