Proceedings | 2016

Introduction of Level of Service and Safety Improvements on the R44 incorporating Access Management Principles


Introduction of Level of Service and Safety Improvements on the R44 incorporating Access Management Principles – Bertie Phillips, Kantey & Templer Consulting  
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The R44 is a major four lane divided arterial route linking Somerset West on the outskirts of Cape Town to the nearby town of Stellenbosch. Daily traffic volumes have increased exponentially from some 5,000 vehicles per day in 1975 to 30,000 vehicles per day in 2015.

Associated with this increase in traffic, there has been a gradual reduction in the level of service and an increase in the crash rate along the route over time. Mindful of this the Road Authority commissioned a study to gather the background data relating to the current operational characteristics of the roadway and safety characteristics including accident statistics (location and type), roadway geometry, intersection location and spacing, as well as intersection and link operational characteristics in terms of level of service. Of critical importance was the investigation and reporting on the location and suitability of all existing accesses and median openings.

Various critical factors were identified as being the predominant contributors to the poor safety record on the route and a range of intervention measures were investigated inclusive of access relocations, access consolidations, the introduction of backage roads, the closure of median openings and the accommodation of U-Turns.

Proposed measures include closure of all the median openings and accommodation of U-Turns by means of roundabout interchanges where vehicle conflicts are reduced substantially and pedestrians, bicycles and public transport is accommodated more effectively. Alternative intersection arrangements varying from stop-control to traffic signals to roundabouts to interchanges were rigorously evaluated at key intersections on the route.

An extensive public participation exercise was embarked upon as part of the process required in order to obtain environmental authorisation of the proposed improvements. A detailed economic analysis was undertaken as part of this exercise in terms of which of the cost-benefit ratios of the various alternative proposed improvements were determined. Multivariate analysis of the benefits and cost in terms of average delay, accident reduction and air quality was used to evaluate the overall performance of the proposed scheme. The results indicate that the implementation of the project would be considered a robust economic deployment of public funding.

The paper provides an insight into the abovementioned background, the investigations and findings as well as the recommended scheme improvements.