A new study by researchers at the University of Virginia looks at the correlation between road design and its effect on the environment.  The goal is to help city and local planners understand the impact of different kinds of road design on congestion and on the environment.  When congestion is reduced, safety is increased, and the environment thrives as well.

Roads are a big source of greenhouse-gas emissions in the United States.  Not only do cars burn gas, but construction and maintenance on roads also consumes cement and tar.  In the United States, road transportation accounts for nearly one-third of all energy consumption and twenty-seven percent of all greenhouse-gas emissions.  As a result, by reducing congestion on the roads by good road design, improving public transportation, and encouraging cycling and walking, we can help the environment as well.

Researchers analyzed the impact of different lane configurations on two-way urban roads, and took into account the physical parameters of the site, such as road gradient, distance between junctions and road width.  They considered costs of annual road maintenance, vehicle fuel, and travel time.  The researchers used the model to understand when interactions between cyclists and vehicles would increase costs for all users and when it would decrease costs.

They found that a lot of well-intended road improvement plans may actually result in greater congestion and more greenhouse-gas emissions because local governments fail to take into account the larger impact of redesigned roads. As an example, it is widely assumed that cycling should be encouraged because it is good for the environment and reduces congestion.  However, cycling will only reduce emissions if all of the extra cyclists do not slow down the traffic.  All the cars sitting in traffic trying to get around the cyclists can actually make things worse.  Therefore, an increase in bike use can actually make matters worse if the roads aren’t updated to accommodate the bikes.  The researchers noted that bikes can particularly slow down traffic on steep sections of roads and where roads are narrow — areas that have great safety concerns for cyclists as well.

This type of integrated approach is an interesting way to approach road design.  Safety and the effect on the environment should be first and foremost on all road planners’ minds.