Barth and Boriboonsomsin, in a recent article, describe the potential benefits of Intelligent Transportation Systems (ITS) strategies as follows:
There are many reasons to fight traffic congestion. Congestion wastes time and money, and it increases the risks of accidents and localized pollutants like particulate matter. But potentially the most serious, if also the least immediate, consequence of traffic congestion is increased emissions of greenhouse gases. Although many people understand that driving contributes to greenhouse gas emissions, the measurement of this phenomenon has been surprisingly crude, often associating carbon emissions only with trip distance, without accounting for how carbon emissions change with vehicle speed.
In our research, we have developed a more finely grained way to measure the relationship between driving and carbon emissions, and this allows us to develop better estimates of how congestion-management techniques can help fight global warming. Specifically, we have estimated how three improvements in managing traffic operations can reduce CO2 emissions:
- Congestion mitigation strategies that reduce severe congestion and increase traffic speeds (e.g. ramp metering, incident management, and congestion pricing);
- Speed management strategies that bring down excessive speeds to more moderate speeds of approximately 55 mph (e.g. enforcement and ISA); and
- Traffic smoothing strategies that reduce the number and intensity of acceleration and deceleration events (e.g. variable speed limits and ISA).
Using typical conditions on Southern California freeways as an example, our research has shown that each of the three traffic-management strategies above could reduce CO2 emissions by 7 to 12 percent. All three strategies in combination could reduce CO2 emissions by approximately 30 percent.
Source: MATTHEW BARTH AND KANOK BORIBOONSOMSIN, TRAFFIC CONGESTION AND
GREENHOUSE GASES, University of California Transportation Center Magazine, Fall 2009
