Dear Editor,
The government in its haste to spruce up the city and its environs in preparation for CWC has embarked on a number of civil works whose execution are unlikely to achieve their desired purpose, inevitably resulting in a waste of scarce taxpayers dollars.
A case in point is surfacing of the steel deck of the Demerara Harbour bridge with a bituminous pavement the purposes for which are probably to improve traction and /or a wearing course to provide a waterproof layer. The problem with the application of a regular bituminous pavement over a steel decking is that it will not last and start deteriorating soon after its application.
Different materials have varying rates of linear and cubical expansion and with the changing daily temperatures, the dissimilar decking materials (steel + bituminous) will be expanding/ contracting at different rates and creating stresses at their interface resulting in cracks developing in the weaker material. With water finding its way through induced cracks in the bituminous pavement, the material starts to quickly unravel and disintegrate.
The other physical forces impacting on the bridge are oscillations due to wind and the movement of heavy vehicles as they traverse the bridge.
These forces cause the bridge to flex and thus induce more stresses in the composite steel deck/bituminous pavement thereby further compounding the deterioration process.
The composition of bituminous pavements is usually specially formulated for bridge steel decking and application of the mixture has to be carefully applied and controlled as per the specs. In the case of the Demerara Harbour bridge it seems that the material used and modus operandi were more in line with the paving of a highway. As is often the case, bridge steel are usually paved with decking material to overcome the problems listed above.
It is unfortunate that with so many potholes in the access road to and around the toll booths, the bridge authority did not see it fit to carry out repairs to this aspect of work on the bridge rather than venture with a costly operation of bituminous paving of the bridge steel deck whose feasibility and effectiveness are still to be established.
Yours faithfully,
Charles Sohan
