Load testing is part of international standard practice

Jul 13, 2025 Letters

Dear Editor,

Kaieteur News – I write to express my concern about an article published in the July 6, 2025 edition of the Stabroek News, in which the Minister of Public Works reportedly indicated that “the new Demerara Harbour Bridge does not need load testing for vehicular or any other traffic and will be fully open and operational to traffic using all five of the planned lanes.”

According to the newspaper, as justification for this, the “Minister explained that the bridge is being built to a certain specification and is being monitored to ensure that this is done, therefore there will be “no need for a trial period” to test vehicular traffic.”

This decision is not in keeping with globally established standard practice for the commissioning of any major bridge, which requires in situ (on site) load testing before it is open to public use. This is typically done even if, as in this case, all the components of the bridge were load tested before assembly because:

the structural behaviour of assembled systems can differ from individual components.
Site conditions (foundation, supports, alignment, etc.) can influence overall performance.
Unanticipated stresses may arise during transport, erection, or connection.

The in situ exercise allows for verification that the actual structural behaviour when the separate components are assembled, matches that of the theoretical or simulated models; detects any construction or assembly errors, settlement, deflection or unexpected vibrations; and ensures the safety of the bridge under static and dynamic loads. Static load testing involves the application of a known weight (e.g., trucks filled with sand) at designated points and measuring deflection, settlement and strain; whereas dynamic load testing involves driving vehicles over the bridge at various speeds to measure vibration, resonance, and damping.

Bypassing in situ load testing may prevent the detection of hidden defects in the construction, joints or foundation. It puts public safety at risk if the bridge fails or behaves unpredictably under load. Legal and reputational liability could fall on both the builders and the government if an incident occurs.

On-site load testing is essential and expected by global engineering standards. Skipping it exposes the public to avoidable risks, and any decision to omit it should be reconsidered. Out of sheer caution and to “make assurance doubly sure” with respect to the structural and functional integrity of the bridge, I urge those concerned to undertake a thorough in situ load testing exercise before fully commissioning the structure and opening it for public use. It would also be useful to have the professional inputs of the Guyana Association of Professional Engineers (GAPE) in this exercise. As Guyanese, we all look forward to the successful completion of this vital developmental initiative and ensure that we leave no stone unturned in our pursuit of an excellent outcome.

Ulric O’D Trotz Ph.D, A.A.

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A.A., Bridge, Demerara Harbour Bridge, international standard, Load testing, Ulric O’D Trotz Ph.D

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