Ectoparasitic mites on rodents: application of the island biogeography theory.

lated this reduced highway need as 4.45 lane-miles (7), and crediting this saving to BART, the freeway-to-rail efficiency ratio changes from 25.2 to 25.1. Construction-energy is not the entire story, however. One must also consider operating-energy. The operating-energies of BART, buses, and cars are 4740, 2900, and 8310 Btu/PM, respectively, including both propulsion energy and a pro rata share of the energy involved in constructing the vehicle (7). Thus, everytime BART attracts someone away from a car it saves energy but, unfortunately, all rail transit systems steal most of their passengers from the existing bus systems, and this wastes energy. BART has the best auto-diversion (46.5 percent, under very generous assumptions) of any rail system, but even so its net operatingenergy saving is only 680 Btu/PM. This operating-energy saving is so small, relative to BART's construction-energy, that it will take 535 years even to repay the energy invested in building the system, much less save any energy. Furthermore, this result is so compelling that even in a transit Nirvana-with double the existing patronage, 75 percent of the passengers coming from cars, and a 50 percent load factor-it would still take 168 years to repay its construction energyRail transit is an energy waster. If we want to improve the efficiency of our transportation systems, we should emphasize the development of more efficient automobiles, because that is where almost all of the existing transportation energy is now being used, and the development of bus-oriented transit systems, because of their energy efficiency. CHARLES A. LAVE Economics Department, University ofCalifornia Irvine 92717