For the immediate future, highway transportation is anticipated to remain the dominant mode of passenger travel in the United States. Vast quantities of energy are consumed by vehicles traveling on the highways. In addition, energy is used for the construction and maintenance of the facilities. To reduce the total consumption of energy, particularly petroleum-based products, highway administrators need to determine how their decisions and design criteria influence the total or life cycle expenditure of energy for construction, maintenance, and use. Highway designs involve trade-offs so that the expenditures of energy to eliminate steep grades or sharp curvatures decrease the total expenditure by each vehicle traveling on the system. In an effort to optimize highway designs (including location) to minimize energy consumption, all phases of the highway system must be examined so that the total energy consumed during the 1 ife of the highway is reduced. It is the purpose of this study to develop and formulate an energy estimating model which explores the energy expenditures for construction, major maintenance, and vehicle operations. Each of these energy-utilizing components is integrated in a PL/1 (Programming Language/One) computer program to predict the total, overall energy expenditure.