Assessment of traffic emission impacts due to rigid pavement rehabilitation activities

Pavement maintenance, repair and rehabilitation (MRR) processes may have considerable environmental impacts due to traffic disruptions associated with work zones. Various sources indicate that greenhouse gas emissions due to traffic delays and additional fuel consumption have increased drastically over the last decades as a result of congestion. The simulation models in use to predict the emission of work-zones are mostly static emission factor models (SEFD) which calculate emissions based on average operation conditions e.g. average speed and type of vehicles. Although these models produce accurate results for large scale planning studies, they are not suitable for analyzing driving conditions at the micro level such as acceleration, deceleration, idling, cruising and queuing in a work zone. The purpose of this study is to address this gap by using integrated traffic micro-simulation emission model which can capture the effects of instantaneous changes in vehicle operation and can provide an accurate prediction of traffic impacts and emissions for a work zone related to rehabilitation of rigid pavements. Software program, INTEGRATION, was used to model real life work zone traffic scenario with traffic emissions around the area. The program is capable of computing vehicle emissions such as hydrocarbons (HC), carbon monoxide (CO), carbon dioxide (CO2) and nitrogen oxide (NOx) for eleven vehicle categories. Changes in emissions were computed by simulating traffic management plans related to traditional and accelerated rigid pavement rehabilitation. The results obtained revealed the feasibility of accelerated construction in reducing the environmental impacts of rehabilitation processes by at least 60%.