The recent article “Life-cycle assessment of high-speed rail: the case of California” (Chester, Horvath) analyzes the entire life-cycle GHG emissions of California’s proposed high-speed rail project. The study has gotten a lot of attention in the media lately, because it claims high-speed trains may have negative benefit in reducing GHG emissions compared to automobiles and airplanes.
The rather obvious point of the article is that train load-factors determine emission savings. Here the authors show this in graph form for the various occupancy scenarios: 100% load-factor and 10% load-factor (single and double trainsets).
Nobody would deny that running nearly empty trains would be wasteful – but is that a plausible scenario? TGV load-factor is 71%. And even the German ICE (which favors clock-face scheduling over load-factors) has around 50%.
The article also states that infrastructure construction must be included in GHG accounting:
The energy and GHG performance of CAHSR is dominated by active operation but shows significant contributions from infrastructure construction and fuel (electricity) production. The primary contribution to the infrastructure construction component is from concrete and steel material production. Construction of retaining walls and aerial track segments are the two largest concrete requirements in the inventory (PB 1999). The production of concrete is energy intensive and releases CO2 in cement production from both fossil fuel use for kilns in clinker production and the calcination of limestone.
The paper makes a major blunder here because it assumes the infrastructure is only intended to provide the HSR express service. In fact, it will be a shared resource and ideally should generate a huge number of commuter trips (over 15 million annual trips in the case of Caltrain). Yes, let’s count the GHG cost of concrete production, but make sure to divide by the total number of users.