SIR - We read that Worcester City Council hopes the bitumen repair to the grouting of the paving slabs in Worcester High Street will do the trick and halt the damage being caused to these slabs by lorries delivering to the shops (Worcester News, March 27).

My advice is not to hold your breath on the matter. Bitumen-based products are wholly unsuitable for long-term repairs in this situation. They are degraded by ultra violet light and become brittle as a consequence. Bitumen's only advantage is that it is cheap, and most engineers know of it.

I have just retired after many years giving talks to builders, civil and highways engineers on modern resin-based products used in cracks and joints which are both flexible and rigid.

These resins have been used successfully for the last 30 years in other parts of the world.

The lack of basic knowledge of most engineers about the techniques to be employed in joint-filling and grouting never ceased to amaze me.

For example, dealing with moving joints such as those in the High Street requires that the joint depth is never more than twice its width and that only the two sides of the joint are in contact with the filling material.

Looking at the photos of the repair and the way they have been carried out, I rather doubt this basic rule has been observed by contractors.

Contractors nowadays need a lot of control but the average engineer looking after the clients' and the taxpayers' interests does not have the skill or experience to spot the problems and passes work as fit when it should be condemned.

In my early days in the trade they employed a clerk of works who was there to see the job was carried out according to specification.

He was God and the Devil rolled into one. Most of the work I see carried out on behalf of local councils, such as here in Worcester, is so badly policed that the contractors are laughing all the way to the bank.

Terry James, Drakes Broughton.