Engineering consultancy WSP has incorporated technologies that compensate for the potential longer time span between maintenance interventions for the rehabilitation of a 27 km section of road in Gauteng, says WSP director Marshall Muthen.
The project, set to begin in January, involves a section of road starting at the D483/P6-1 intersection, close to Bapsfontein, in Ekurhuleni, and ending at the D483/D713 intersection in Cullinan, in Tshwane.
The section of road serves as a connector between small towns, as the road is mostly trafficked by light vehicles and medium-sized trucks transporting cargo between the towns. Occasionally, hauler trucks transporting agricultural goods, also use the road.
Muthen explains that the categorisation of the road, including the nature of the traffic using the road and physical location, impacted on the design aspects of the project.
“There are design standards that are legislated in terms of best practice for a Class 2 road, and we follow all those standards. These aspects must be considered so that the alignment of the road and signage used are chosen to allow for maximum safety and visibility to road users, particularly for upcoming road hazards such as intersections, overtaking or stopped vehicles and even potholes.”
As commercial activities in these towns are vital for local economies, WSP needed to consider accommodating traffic during construction without impeding vehicle flows and delaying local activities for too long.
WSP’s design also included road surfacing that minimises road noise in the more urban areas.
Upgrades and Maintenance
The road maintenance project will upgrade four existing gravel surfaced intersections to asphalt surfacing.
Muthen stresses that these upgrades are important in cases where a gravel road intersects with a high-quality asphalt road because vehicles that were driven on a gravel road and then on an asphalt road can pick up loose gravel and deposit it onto the asphalt road.
“Loose rock and stones collect on the surface of that intersection, causing damage to the pavement. Large stones also get embedded into the asphalt, and eventually become a defect that will develop into a pothole.
“Secondly, if you have debris picked up from the gravel road coming onto asphalt road, this poses a safety danger to traffic, and can lead to accidents and damage to vehicles.”
Muthen adds that upgrading the intersections with asphalt will allow for sufficient time during which debris can be dislodged before the vehicles enter the main road. The surfacing on the gravel road approach at the intersection also helps with safe braking and predictable speed reduction, improving safety.
The construction phase will also include milling out areas of the road that have existing “cold mix” pothole repairs and will inlay these areas with continuously graded hot mix asphalt.