Analysis of Traffic Operations with the Addition of a Truck Climbing Lane—Case Study for I-80 in California

Truck climbing lanes are designed to enable a slow stream of heavy vehicles in segments with a high road incline. Research has shown the positive safety effects of these lanes as they separate slow traffic from non-slow traffic. In higher road slopes, many vehicles are restricted to follow a heavy vehicle before they can overtake on the adjacent lane. This becomes a more pressing issue with higher demands on the highway as the frequency of lane changes increases. With the addition of truck climbing lanes onto multilane highways, a change in the speed profile of each lane in a multilane highway is observed. In this study, the addition of a truck climbing lane in the Placer County of California is investigated. The truck climbing lane is constructed in the eastbound direction besides the existing two lanes on the I-80 corridor in Placer County. The before and after analysis of this construction revealed that the average speeds in the two existing lanes increase from 60.6 mph to 64.4 mph in the horizon year (2046) as faster vehicles are not restricted to periods of following heavy vehicles. Also, the increase in speeds increases the highway throughput in the horizon year. Furthermore, additional to the capacity increase, the truck climbing lane can reduce unnecessary rapid braking and passing on the non-truck climbing lanes which would yield more environmental-friendly operation of the multilane highway.