Level of Service of Multi-Lane highway Section under fluctuated traffic flow condition: a state-dependent Discrete-Event Simulation framework

Multi-lane highways have moderate to high capacity and designed to provide a balance between traffic mobility and accessibility. The assessment of Level of Service (LOS) of multi-lane highways is traditionally based on the Highway Capacity Manual (HCM). However, the HCM method does not takes into account randomness in vehicular flow as well as state-dependent speed of vehicles on multi-lane highways, which do not depict actual conditions. To aid the traffic and highway designers as well as to capture the randomness in the vehicular arrival flow and state-dependent speed, a Discrete-Event Simulation (DES) framework using the Phase-Type Distribution is developed. The Phase-Type distribution takes into account randomness in the vehicular flow. The LOS computation under different settings of design parameters shows that the vehicular arrival rate, Squared Coefficient of Variation (SCV) in the inter-arrival time and number of lanes significantly affects the LOS of multi-lane highways. The length of multi-lane section also has an influence on the LOS, which is ignored by the HCM. The proposed DES framework will assist the traffic and highway designers to make smart choices in LOS computation.