There are no distinct peak hours on these roadways, but rather constant congestion indicating that the shortage of capacity in the peak causes traffic to spread into the adjacent hours. This congestion is not going away. The greater metropolitan New York City region has unhealthy air quality in terms of smog, ground level ozone, and is at a level of severity just below the nation's worst air quality in the Los Angeles area. Ground level ozone is a function of VOC and NOx emissions - more than half of these are from vehicle transportation. Manhattan is also in violation of particulate standards, both the current and the proposed more stringent standards - and the levels have deteriorated in recent years.
Trucks are a large contributor to poor air quality in the region.
Heavy-duty long haul vehicles travel many more miles than cars, and their vehicle miles traveled are increasing. Diesel, while efficient in some respects, emits extremely fine harmful particulates. The number of people coming in by car are twice the number of those in Paris, almost three times London and almost six times Tokyo. The CBD, congested with people and vehicles, is reachable by highly congested roadways. Most goods come to the CBD from west of the Hudson, where most of the warehouses and the major part of the seaport is located.