| The timely, efficient, and quality completion of highway projects partly depends on the selection of the appropriate work shift. Certainly there are advantages and disadvantages for both day and night shifts. Daytime operations are generally considered to be safer for both workers and motorists because of better visibility and a higher state of alertness. However, to accommodate the flow of higher daytime traffic volumes, work zone lane closures may not be possible--and the option to work during the night becomes a serious consideration. A highway project's characteristics may favor a particular work shift. Type of work, lane capacity, average daily traffic (ADT), work zone accidents, project duration, and project costs are some of the issues that may dictate shift times.;This research is aimed towards the development of a decision model that will incorporate all the factors that may influence the selection of either a day or a night work shift. The process is based on a decision tree representing qualitative and quantitative factors, ranked in the order of importance. The shift selection methodology is similar to the human reasoning process and that is why a knowledge-based system approach has been chosen for this decision model. An expert system shell has been utilized to develop the knowledge base, which consists of IF-THEN logic rules. The rule-based knowledge structure also has the option to interface with an external traffic count database for the purpose of lane closure analysis.;The model approach to work shift selection includes mathematical reasoning in the analysis of traffic congestion, vehicle accident numbers, motorist (user) costs, and project (owner) costs. The final solution offered by the knowledge-based system model consists of the recommended work shift, number of daytime lane closures allowed, user cost savings for a night shift option, and percent change in total owner cost for a nighttime alternative. |
