Surface upgrade for Soesdyke Linden Highway imminent

Sep 02, 2013 News

Rehabilitation of several sections of the Soesdyke Linden Highway (SLH) to the tune of $57.5M is expected to commence shortly, according to Cabinet Secretary Dr. Roger Luncheon.
According to a private engineer knowledgeable about the SLH, “There is need for rehabilitation of the wearing surface of the highway at this time, but this requires funding to bring it about.”
The engineer asserted that current expenditure on maintenance of the highway should not be correlated with the quarrying of sand in its vicinity but should be connected with recommended highway maintenance practice.
It was noted that feasibility studies for the design and construction of highways usually have a 20-year horizon. During such a period, the capital investment in the highway would have been recovered either as toll revenues or as benefits to road users if no tolls are charged for the use of the highway.
Providing a brief history of the SLH, he said the structure was constructed from 1966 to 1968 and has therefore been in use for 45 years. It underwent rehabilitation in the mid 1990s, which involved the demolition of nine timber bridges and their reconstruction with reinforced concrete, the paving of the highway from Soesdyke to Kuru-Kuru with a new asphaltic concrete surface, and the sealing of cracks in the wearing surface between Kuru-Kuru and Linden with asphalt. Those works cost US$11 million.
The engineer recalled that some depressions in the surface of the highway were diagnosed as being due to the changing exterior of the existing ground by excavating sand from one part and depositing it in another part.

The Soesdyke Linden Highway

“What is called cutting and filling, caused the water table in some locations to come into contact with the sand below the highway base. This reduced the support given by the sand to the base and weakened the base. This problem was eliminated by construction of what were called French drains in the sand below the base in such areas,” the engineer explained.
He noted that the existence of sand quarries along the highway in general does not affect the structural stability of the highway, provided that the quarrying is done in accordance with regulations.
According to the engineer, highways are usually designed with either flexible or rigid pavements. The SLH has a flexible pavement design that is made of stabilised soil bases and an asphaltic concrete wearing surface.
He explained, “Its base (the load distribution component of the road structure) is constructed with white sand stabilised with asphalt. Flexible pavements deflect under wheel loads with most of the deflection disappearing after the wheel load passes. A small amount remains, which accumulates over the years until they become noticeable to the road user.”
The engineer added that the quality of the vehicle ride on the asphaltic surface deteriorates and eventually requires a rehabilitation of the wearing surface to restore it to its original smoothness. This is done by paving the highway with a new asphaltic concrete surface, or by physically digging up the existing surface, recovering the sand and crushed stone, mixing these with new asphalt and paving the highway with these recycled materials.
He said in more developed countries, best practice for maintaining the riding quality of asphaltic concrete highways is to renew the wearing surface at intervals of 15 to 20 years.