Police spent nearly five hours guarding gallons of beer which fell off the back of a lorry as congestion mounted on a busy Swindon road.

But the mountain of cans of lager stacked on the pavement in Wootton Bassett Road were not contraband it was the result of a misjudgement by a lorry driver.

The driver had attempted to steer his 16ft high articulated lorry under the 15ft high railway bridge, and it became jammed.

The accident caused hundreds of cans of beer to fall into the road. The load was on its way to Iceland's distribution centre in Penzance Drive.

One driver stuck in the resulting traffic jam, Pauline Howard, a 42-year-old personal assistant from Old Town, said it held her up.

"I wondered why all the traffic was building up and all I could see was lights flashing," she said.

"Then when I went past I could see a huge mountain of beer you could have had a hell of a party with that lot!"

The accident happened at about 6.15pm on Wednesday.

The road was closed from the Mannington roundabout to the bridge for nearly two hours as police attempted to dislodge the lorry.

Railtrack had to call in a bridge examiner and stopped all train movements between 6.20pm and 7.25pm. A 5mph speed restriction was then in force on the line until 7.40pm.

It was not until 8.15pm that the debris was completely cleared and even then two police cars were forced to guard the cans of Grolsch and Stella Artois for a further two and a half hours until they could be collected by Iceland.

Wiltshire Police spokes-man Graham Chivers said: "It certainly took up a lot of police time for someone just underestimating the height of his lorry.

"There was some serious traffic congestion and a lot of beer."

The crash further highlights the problem of truckers crashing into bridges which are too low for their vehicles.

Only a month ago, Railtrack and the Automobile Association unveiled a list of the country's most bashed bridges, which included the Whitehouse Road bridge in Swindon.

Whenever a bridge is hit, Railtrack is forced to slow trains crossing over it.

Its own report revealed that last year more than 1,500 railway bridges were hit by tall vehicles.

On some occasions, unlike Wednesday's accident, people have been injured or even killed.

Railtrack spokeswoman Jo Anne Couzins said: "A lot of disruption was caused by this incident.

"Trains were held up and passengers delayed on their journeys.

"It's amazing how much trouble one man can cause."