This work analyzes the impacts of different light-duty trucks (LDTs) on the capacity of signalized intersections. Data were collected at two intersections in Austin, Texas, and regression analysis generated estimates of mean headways associated with various categories of LDTs, as well as passenger cars. Using the estimated headways Passenger Car Equivalents (PCEs) were calculated, and these suggest that the impacts of light-duty trucks should be given special consideration when analyzing the capacity of signalized intersections. For example, a single large sport-utility vehicle in through traffic is equivalent to 1.41 passenger cars; and a van is equivalent to 1.34. Such long headways reduce intersection capacity and increase urban congestion.
We find that most car models are as safe to their drivers as most sport utility vehicles (SUVs); the increased risk of a rollover in a SUV roughly balances the higher risk for cars that collide with SUVs and pickup trucks. We find that SUVs and to a greater extent pickup trucks, impose much greater risks than cars on drivers of other vehicles; and these risks increase with increasing pickup size. The higher aggressivity of SUVs and pickups makes their combined risk higher than that of almost all cars. Effects of light truck design on their risk are revealed by the analysis of specific models: new unibody (or “crossover”) SUVs appear, in preliminary analysis, to have much lower risks than the most popular truck-based SUVs. Much has been made in the past about the high risk of low-mass cars in certain kinds of collisions. We find there are other plausible explanations for this pattern of risk, which suggests that mass may not be fundamental to safety.
What I long for is automated cars
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