A missing expansion joint on the Marsa flyover made headlines earlier this week and the Infrastructure Minister blamed it for a gaping hole that formed in the road. What is an expansion joint and what does it do? Claire Caruana spoke to civil structural engineer Marc Bonello to find out.

The infamous expansion joint that has yet to be installed at the recently opened Marsa flyover was the butt of many jokes this week.

But according to the head of the University of Malta’s Civil Structural Engineering department, Marc Bonello, the structure is a crucial component – and it is no laughing matter.

On Monday, Times of Malta reported that a ‘crack’ had developed on the underside of the flyover. Infrastructure Minister Ian Borg attributed it to missing expansion joints that are expected to be installed in the coming weeks.

What is an expansion joint?

An expansion joint, which could be made of materials such as rubber or silicone, is installed to relieve stress on bridges and flyovers and can be found in other structures all over the island.

In most cases they are located at the edge of the structure, as in the Manuel Dimech Bridge in St Julian’s. The ones on the Marsa flyover are less common in Malta as they will be located mid-way through the structure, according to Dr Bonello.

He said this was likely a choice based on the design concept requested by the government, which had to be adhered to for the contractor to win the contract for the project.

There shouldn’t be a technical reason why this was all left until the end

One is not safer than the other, he added. Those used on the junction just off the Mrie─žel Bypass had joints similar to those planned in Marsa, he said.

The only problem that could occur was if, when carrying out any repair works or general maintenance, the asphalt is laid over the expansion joint.

“In Malta we tend to just lay the asphalt without lifting out the expansion joints. That could be a problem in the long-term because asphalt breaks,” Dr Bonello explained.

Still safe without expansion joint but...

He echoed comments that he had made earlier in the week, that not having the expansion joint in place was still safe, but he questioned why it had not been installed at an earlier stage as usually happens.

“There shouldn’t be a technical reason why this was all left until the end,” Dr Bonello said.

Aside from reports of a “crack” on the underside of the flyover, last week urgent repairs had to be carried out after a hole appeared in the flyover’s road surface.

While the Infrastructure Minister dismissed the issue, insisting the gaping hole was “not a pothole”, many took to social media to question whether the flyover had been inaugurated too early.