(19)

(11)

EP 1 407 081 A1

(12)

(43) Date of publication: 14.04.2004 Bulletin 2004/16 (21) Application number: 02788062.4 (22) Date of filing: 11.07.2002

(51) International Patent Classification (IPC)7: E01F 9/047 (86) International application number: PCT/GB2002/003201 (87) International publication number: WO 2003/023147 (20.03.2003 Gazette 2003/12)

(84) Designated Contracting States: AT BE BG CH CY CZ DE DK EE ES FI FR GB GR IE IT LI LU MC NL PT SE SK TR Designated Extension States: AL LT LV MK RO SI (30) Priority: 13.07.2001 GB 0117166 (71) Applicant: PRISMO LIMITED Crawley,West Sussex RH10 6UE (GB)	(72) Inventor: WATTS, Gregory Robin,Transp. Res Lab. Limited Berkshire RG45 6AU (GB) (74) Representative: Fenlon, Christine Lesley  Haseltine Lake,Imperial House,15-19 Kingsway London WC2B 6UD London WC2B 6UD (GB)