Comprehensive level of service: Needed approach for civil infrastructure systems

Levels of Service for infrastructure systems should be defined in terms of both capacity (Level of Availability) and maintenance (Level of Operation). Levels of Service for a highway system consider capacity, but assume good pavement conditions. This neglects the effect that deferred maintenance could have on a reduction of capacity. Likewise, maintenance Levels of Service definitions, although serving as trigger points for accomplishing maintenance activities, do not consider the impact that deferring or failing to accomplish maintenance has on highway capacity. A Comprehensive Level of Service is thus defined and modeled to account for both the impact of deferred maintenance and highway obsolescence, which is defined as the inability of a highway system to carry traffic volume as designed. A system dynamics approach is taken because of the complex nature of the problem and the feedback loops that are developed with the interrelationships between the Comprehensive Level of Service and the effect on the socioeconomic system. The model variables and parameters form the basis for a targeted data collection effort for defining a management information system that will aid future decision making concerning transportation system maintenance and construction programs.