The incorrect use of materials and a flawed design process have been cited by Civil Engineer Phillip Allsopp as reasons for the cracking of the Railway Embankment Roadway.

Allsopp is a former head of the government’s Hydra-ulics Division in the Ministry of Works, who has considerable experience in infrastructure works.

It had been observed that long stretches of the little used East Coast road had huge cracks and that creases had begun to develop.

Minister of Transport and Hydraulics, Anthony Xavier had ordered a report to be done on the causes of the flaws and this was subsequently submitted, but later returned to engineers for simplification.

The defects liability period for this project has expired and it means that costly repairs will have to underwritten by the state.

Questioned recently on the report, Minister Xavier had said that he had ordered engineers to prepare a detailed report listing causes for the defects and those culpable.

He nevertheless did acknowledge that the failures were in large measure the result of design flaws.

Previously, Stabroek News had not had much luck in persuading the ministry to comment on the findings of the report, thus the approach to Allsopp.

According to Allsopp, the faults have in one instance been a casualty of the design technique referred to in engineering terms as ‘benching’.

“The Benching technique seems to have been faulty and the sand/clay mix not properly blended to reach the required standard necessary for plasticity.

The plasticity of the sand/clay mix was probably not adequately controlled”, Allsopp said.

Benching is achieved by cutting a bench shape into a portion of an existing structure and levelling that material over an area not previously covered by the surface.

Allsopp said this method was used when there was a need to widen the surface area, as was the case of the Embankment Road, where previously there had only been a mound on which the sleeper for the tracks had rested.

The American Consulting Firm Wilber Smith and Associates in association with David Klautky and Associates oversaw the project.

Klautky, contacted yesterday said that neither his firm nor the American firm was responsible for designs but were merely there as supervisors to see that the designs were carefully followed.

Trinidadian company Dipcon, which through an Inter-American Development Bank-funded contract, was selected to construct the road, echoed similar sentiments. It said it had followed designs provided to guide its work.

According to Klautky, the materials had been placed according to the design specifications, which were prepared by a different group.

Smith and Klautky did not supervise work on the entire stretch of road as funding ran out resulting in the Ministry of Public Works doing some of that supervision.

During its construction, Dipcon used the sand/clay material, which is found in abundance around the Timehri area. The reddish brown mix has been a base material for road construction since the mid 1950s.

According to Allsopp, he first developed it as a base material onto which several road surfaces, including Carifesta, Homestretch and Mandela Avenues had been laid.

However, it needs to undergo laboratory evaluation to arrive at the correct mix.

He suggested engineers may have heard about the sand/clay mix, but either did not know the mixing technique or how to test it to determine the right consistency.

Allsopp said this lack of knowledge would continue to lead to failures in road structures where the guidelines were not followed, as was the case with the Embankment road. Questioned about remedies, Allsopp said the only solution was for the entire stretch of road to be dug up and re-laid.

This would entail removing the top surface and the base material and re-packing it with the correct mix before re-applying an asphalt surface, the cost of which would run into millions of US dollars.

Meanwhile, Allsopp is calling for the establishment of an authority to administer the country’s road network, similar to that of the water authority, the sea defence board and the Drainage and Irrigation Board.

Although acknowledging that some authority for controlling roads lay with the police and also the minister, these could be better served through administration by a regulatory body, he said.

The civil engineer was also critical of the number of individual access points to the embankment highway, something he put down to bad planning, while saying it was a recipe for serious accidents.

Questioned about the proliferation of businesses along the road, Allsopp saw these as damaging to the shoulders of the road and encouraging parking close to the shoulders.

The Ministry of Public Works is in the process of reviewing certain businesses along the Embankment Road, particularly concrete block- making.

He was particularly worried about parking on a high-speed highway, while noting that vehicles should be entirely off the road.

He worries that ruptures in the pipes could undermine the roads. If these have to be sited near to the road shoulder, then they should be sleeved.