Ex-ante evaluation of Longer and Heavier Vehicles in Flanders – a driving simulator study

Abstract

Background: The Flemish government is considering the implications of allowing the use of Longer and Heavier Vehicles (LHVs) for road freight transport. These megatrucks can measure up to 25.25m (instead of 18.75m) and weight up to 60 tons (instead of 44 tons). Such trucks are already in circulation in some of the EU Member States (e.g. Sweden, the Netherlands). This driving simulator study is part of a pilot project that’s investigating the advantages and disadvantages of introducing LHVs in Flanders (Belgium). Objectives: To get more insight in the drivers’ behavior when drivers are overtaking an LHV or when they are entering/exiting a highway in the presence of an LHV. Getting more insight in the behavior of the LHVs drivers is not the scope of this driving simulator study, but this is investigated in another subproject within the pilot project. Methodology: The experiment is conducted on a medium-fidelity STISIM driving simulator and the visual virtual environment is presented on a large 180° field of view seamless curved screen, with rear view and side-view mirror images. The driving simulator consists of a mock-up and is equipped with a faceLAB eye tracking system. Fifty participants are exposed to different conditions of entering/exiting the highway and overtaking maneuvers. Results & conclusions: We can conclude that there is little difference between the regular truck and LHV conditions in case of overtaking maneuvers on a secondary road or entering/exiting a highway. However, some important findings that road authorities should take into consideration are: Drivers need a longer distance to perform the overtaking maneuver on a secondary road in the LHV condition; Drivers tend to drive closer to the right side of the road after overtaking an LHV. Therefore, only allowing LHVs on roads with physically separated cycle lanes can be an option; Drivers need a longer distance to enter the highway safely in the presence of an LHV. Therefore, the merging lanes on highways might be provided with an emergency lane with a minimum length of 250m. Additionally, a warning sign at the backside of the LHV is very useful to inform the drivers that they are driving behind a truck with a length of up to 25.25 meters.