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Fuel cells have attracted a great deal of attention in the last few years as potential replacements for conventional gasoline- or diesel-powered internal combustion engines. This study evaluated the potential life-cycle environmental impacts of a fuel cell vehicle (FCV) using a 50 kW proton exchange membrane (PEM) fuel cell system (both with and without a fuel reformer), and compared them with those of a gasoline-fueled internal combustion engine vehicle (ICEV). The fuels considered for the fuel cell systems were direct hydrogen (without reformer), and methanol and gasoline (with reformer). Exclusive of the propulsion systems, the rest of the vehicle was assumed to be the same across all the profiles.

This project team conducted a life-cycle-based environmental evaluation of new, lightweight materials (e.g., titanium, magnesium) used in two concept 3XVs -- i.e., automobiles that are three times more fuel efficient than today's automobiles -- that are being designed and developed in support of the Partnership for a New Generation of Vehicles (PNGV) program. The two concept vehicles studied were the DaimlerChrysler ESX2 and the Ford P2000. Data for this research were drawn from a wide range of sources, including: the two automobile manufacturers; automobile industry reports; government and proprietary databases; past life-cycle assessments; interviews with industry experts; and models.

The critical speed method uses measurements of the radii of yawmarks left by vehicles, together with values for centripetal acceleration, to estimate the speeds of the vehicles when the yawmarks were made. Several field studies have indicated that equating the centripetal force with braking friction produced biased estimates, but that the biases tended to be small (e.g. within 10%-15% on average) and led to underestimates, suggesting that the method can be useful for forensic purposes. Other studies, however, have challenged this conclusion. The critical speed method has also seen use in safety-related research, where it is important to have a reliable assessment of the uncertainty associated with a speed estimate. This paper describes a variant of the critical speed method, where data from field tests lead to an informative prior probability distribution for the centripetal acceleration.

Martinez and Schlueter [6] described a three-phase model for reconstructing tripped rollover crashes, where the vehicle's path is divided into pre-trip, trip, and post-trip phases. Brach and Brach [9] also described this model and noted that the trajectory segmentation method for the pre-trip phase needed further validation. When a vehicle leaves a measurable yaw mark at the start of its pre-trip phase it might be possible to compare estimates from the three-phase model to those obtained using the critical speed method, and this paper describes Bayesian reconstruction of two such cases. For the first, the 95 percent confidence interval for the case vehicle's initial speed, estimated using the critical speed method, was (64 mph, 81 mph) while the 95 percent confidence interval via the three-phase model was (66 mph, 79 mph).