[1] Univ West London, Sch Comp & Engn, St Marys Rd, London W5 5RF, England
[2] Univ Rome Tre, Dept Engn, Via Vito Volterra 62, I-00146 Rome, Italy
[3] Natl Tech Univ Athens, Dept Transportat Planning & Engn, 5 Iroon Polytechniou St, GR-15773 Athens, Greece