TRB’s Transportation Research Record: Journal of the Transportation Research Board, No. 2123 includes 19 papers that explore linking transportation planning and the National Environmental Policy Act processes, idling reduction of heavy-duty diesel trucks, in-cab air quality of trucks using different air conditioning methods, comparative assessment of three dispersion models in predicting near-road particulate matter concentrations, in-use emissions from refuse trucks, emissions inventories for construction vehicles, energy and environmental impacts of high-speed roundabouts, a macroscopic emission model for China, and particulate emissions from transit buses. This issue of the TRR also examines the effect of high-occupancy toll lanes on mass vehicle emissions, environmental impacts of high-emitting vehicles, emission modeling of freeways with high-occupancy vehicle facilities, environmental impacts of a major freight corridor, planning of combined wildlife and pedestrian highway crossings, vehicle pass-by noise emission levels from onboard sound intensity levels of tire-pavement noise, measuring vertical distribution of truck noise sources during pass-bys by acoustic beam forming, test variables for onboard sound intensity measurements, preserving a historic national park roadway, and environmental impacts of cured-in-place pipe.