Emissions Due to Construction Equipment and Traffic Delays – Task 6: Contribution of Vehicular Emissions Caused by Reduction in Capacity During Roadway Construction

Task 6 modeled an array of possible construction work zone projects with respect to facility demand (low, medium, and high average annual daily traffic [AADT]); facility cross section (two to five lanes); number of lanes closed (one to four lanes); and work zone schedule (seven different schedules modeled). The work zone schedules included a base or typical schedule, overnight schedule, and schedules to accommodate the proposed construction bans in Dallas, Texas (banned from 06:00 to 10:00), and Houston, Texas (banned from 06:00 to 12:00), for peak and off-peak directions of flow. The research team used QUEWZ-98 to calculate delays and road user costs associated with work zones and quantified operational characteristics of traffic flow through work zones, which served as inputs to the alternate emissions model (referred to as the Emissions Workbook) developed in this task. The results from the simulations were assembled into a large matrix table that had both the road user cost and emissions data. From this table, a series of graphs were created for each geometric/volume scenario with a series of curves representing the different road closure scenarios. These graphs provide the user a means of comparing the different road closure scenarios. The impact of schedule and number of lanes closed are presented in road user cost, nitrous oxide (NOx), carbon monoxide (CO), and volatile organic compounds (VOC) graphs for all scenarios. Two sample problems guide the user on the use of the tables and graphs.