by Abigail Schantz
Chester and Horvath from the Department of Civil and Environmental Engineering at UC Berkeley determined that a life-cycle environmental inventory was necessary to fully understand the pros and cons of the proposed project. The life-cycle environmental inventory reviews emissions resulting from use of this transportation method as well as the environmental costs of building and maintenance. Presently, people traveling in this corridor rely most heavily on automobiles, secondarily on airplanes, and lastly on heavy rail transit. Because we are unable to predict the precise usage of a high-speed rail system, when comparing the environmental impacts of each of these modes of travel, it is critical to take into account differences between low-demand and high-demand scenarios, and to account for an expected initial transition period of low-usage. Additionally, relatively small differences in the design of the rail can make drastic differences in the environmental impact, such as use of smaller cars seating approximately 600 passengers as opposed to larger ones seating approximately 1,200, which require more energy than smaller cars. Using this kind of information about components of the system, a return on investment (ROI), calculated at 9.7 million Mg CO2 emissions, model can be created. Chester and Horvath found this model estimates that with other travel modes at low occupancy and high-speed rail at high occupancy, the ROI for energy and green house gas (GHG) would be 8 and 6 years respectively. In the opposite scenario, with other forms of transportation at high occupancy and high-speed rail at low occupancy (as is probable during the initial transition period), neither energy nor GHG would ever return the investment. Lastly, with all transportation at mid-level occupancy, the ROI for energy would be 28 years and for GHG, 71 years. These estimates suggest that under optimal occupancy, the high-speed rail would lower both energy and GHG emissions. On the other hand, it is likely that construction of the high-speed rail would greatly increase other emissions such as SO2 due to the system operating primary on electricity, which also must be taken into account. Decision-makers will have the opportunity to increase the environmental benefits of the rail during construction, for example, by utilizing lower-CO2 concrete mixes or minimizing concrete usage in the design, as the production of concrete is energy intensive and releases large amounts of CO2.
Chester, M., Horvath, A., 2010. Life-Cycle Assessment Of High Speed Rail: The Case Of California. Environmental Research Letters, 014003-014003. http://iopscience.iop.org/1748-9326/5/1/014003/