HC Deb 07 July 1971 vol 820 cc392-4W
Mr. Wiggin

asked the Secretary of State for the Environment whether he will set up an inquiry into the circumstances that led to his decision partly to close 42 bridges and to delay the construction of 61 others.

Mr. Peter Walker

My decision was the result of an inquiry in that it was taken following consideration of the implications of the interim design appraisal rules recommended by the technical committee on large steel box-girder bridges set up last December under Dr. Merrison. This consideration showed that bridges in service might be subject to some very slight post-construction risk.

Whilst recognising that this risk was slight I decided in order to safeguard the public to restrict traffic using trunk road bridges until their design had been satisfactorily re-appraised and to require the design of trunk road bridges under construction to be re-appraised also. Highway authorities responsible for bridges of this type on non-trunk roads were advised to take similar action.

Mr. Wiggin

asked the Secretary of State for the Environment, in view of his decision partly to close 42 box-girder bridges and to delay construction of 61 others, what is the cost to his Department and to highway authorities; if he has estimated the cost of traffic delays; who will carry out inspections and how long they will take; who will pay for necessary improvements; what delays are forecast in those bridges now being built; and how many of this type are planned.

Mr. Peter Walker

The Merrison appraisal rules are complex and incorporate new procedures which those using them will need time to master. At this stage it is not possible accurately to forecast dates for the completion of design reappraisals, delays to construction, or costs likely to result. Progress is being monitored to ensure that delays are kept to a minimum.

No estimate is being made of the cost of traffic delays because I consider the need completely to safeguard the public is of first importance.

Design inspections are being carried out by the office responsible for the design, with additional assistance wherever appropriate to ensure that the appraisal is completed as rapidly as possible.

Where strengthening is found necessary the Department will bear the cost for trunk road bridges and grant-aid principal road ones. For others the costs will need to be borne by the owner concerned.

In England a further 23 road bridges of this type are at the design or tender invitation stage, and are being checked so as to ensure conformity with the interim rules.

Mr. Wiggin

asked the Secretary of State for the Environment whether he has yet received a report from the Technical Committee on steel box-girder bridges which was set up last December; and whether he will make a statement.

Mr. Peter Walker

Yes, I received their interim report on Friday, 2nd July. I appointed the Committee in association with the Secretaries of State for Scotland and Wales and I shall discuss with them the contents of the report and its recommendations.

The report has two appendices. One contains interim rules for the appraisal of designs and these have been made known to all engineering offices in this country actively engaged in the design of steel box girder bridges. The other appendix is concerned with methods of construction and contractual procedures and is being studied.

The Committee have found no reason for doubting the safety and general soundness of bridges of this type when these bridges conform to the rules which the Committee have formulated. These rules take account of the most recent research. This guidance cannot do other than have a constructive influence on the use of steel for bridges by providing more detailed design criteria than have previously been available.

The development of this kind of steel bridge has been a great technological advance in which British engineers have played a major part. I am assured that when complying with the Committee's rules there will be no doubt as to the dependability of these bridges and that considerable economies will continue to be achieved by using this form of construction. I appreciate the work which Dr. Merrison and his colleagues have done in producing so speedily their report on this complex subject.