Vehicles becoming stuck under Walmgate Bar, which have threatened the future of an historic York monument, should be a thing of the past when new traffic restrictions are enforced.

Measures to stop motorists travelling through Walmgate Bar will come into effect from November 1, when a 12-month experimental order will prohibit vehicles coming through the Barbican.

All vehicles - except cyclists - will be banned from proceeding beneath the lower and most southerly of the two road archways to protect the Bar, which has been struck almost a dozen times by vehicles in recent years.

The Bar, first mentioned in the 12th Century, is the best preserved medieval town gateway in the country - retaining its portcullis and 15th Century wooden doors. It was the focus of intense attacks during the Siege of York in 1644.

In the last seven years, it has been under attack by a succession of vehicles, which have struck or become lodged in the gateway - costing thousands in repairs.

The new traffic order will see Walmgate become completely traffic light-controlled at its junction with Foss Islands Road, with vehicles taking turns to use the whole of the remaining carriageway.

Work has been under way in recent weeks to make Walmgate ready for the changes. After evaluating the scheme's success, the council will then decide whether to make the order a permanent fixture.

Ann Reid, the council's executive member for transport, said: "This is something many people have asked for. We need to protect Walmgate Bar more than we have been able to in the past.

"We needed to develop a scheme which prevents people from using the central part of the Bar altogether. It is one of the finest examples of a Barbican in the country and a few seconds on a journey is a small price to pay to protect this ancient monument."

Tracey Simpson-Laing, Labour's shadow transport spokesman, said: "The protection of the Bar is vitally important to the walls of the city.

"We hope that the regulation of the road will work successfully. But, if not, then we hope it will be brought back to planning meetings for a decision after three months where we can discuss how it is going."

Updated: 10:34 Friday, October 22, 2004