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Submitted on: 15 March 2002.
Revised on: 12 April 2002.
Accepted on: 09 May 2002.
PROCEEDINGS OF THE INSTITUTION OF CIVIL ENGINEERS-TRANSPORT
Submitted on: 27 May 2004.
Revised on: 17 June 2004.
Accepted on: 15 July 2004.
PROCEEDINGS OF THE INSTITUTION OF CIVIL ENGINEERS-TRANSPORT
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