Dear Editor,
I refer to earlier letters written to the press on the Hope Project. I am concerned about the weight of these pre-stress bridge units being manufactured at Onverwagt that will be transported by road to the construction site at Hope ECD, crossing several bridges including the vulnerable long span bridges at Mahaica and Mahaicony.
I have reviewed the contract bid documents including the bridge drawings dated June 10, and note first of all the drawings were approved by RB Latchmansingh but no one signed as the designer. SRK and Mott MacDonald’s names are also on the drawings. How can anyone approve these drawings without a designer’s signature? From my experience these drawings appear to be a wholesale copy from typical American Standard Drawings. The specs are also typical for American conditions. The specs call for a concrete strength of over 7200 lbs per square inch at 28 days in, which is impossible to achieve under Guyana’s conditions.
The central span of the bridge calls for 6 nos. pre-stress beams, 6΄0 ft deep, 40 metres long (131 feet) while the weight for each beam is calculated as 60 imperial tons. Can these bridges even if one beam is transported at any one time sustain such a load, particularly the Mahaica and Mahaicony long span bridges? These bridges were rebuilt a few years ago, but I am not sure as to what AASHO loading they were designed for.
Several lifting cranes will also have to be employed to offload and install these beams on their supports at the Hope site. I am surprised the consultants did not apprise the contractors bidding on the project of the weight of the beams during the time of tender.
I am also concerned about the 34 metres (112 ft) long concrete piles designed to support the central span of the bridge piers, which are over 131 ft long. These piles will suffer the same fate as the 120 ft timber piles driven for the 8-door sluice that broke during driving. This will ultimately compromise the structural integrity of the bridge as a whole.
I am calling on the NDIA which is responsible for this project to initiate a review of the entire design of the project before proceeding further.
Yours faithfully,
Malcolm Alli
