An exact algorithm for the capacitated arc routing problem with deadheading demand

We study an extension of the capacitated arc routing problem (CARP) called the capacitated arc routing problem with deadheading demand (CARPDD). This problem extends the classical capacitated arc routing problem by introducing an additional capacity consumption incurred by a vehicle deadheading an edge. It can be used, e.g., to model time or distance constrained arc routing problems. We show that the strongest CARP lower bounds can be weak when directly applied to the CARPDD, and we introduce a new family of valid inequalities shown to significantly strengthen these bounds. We develop an exact algorithm for the CARPDD based on cut-and-column generation and branch and price, and we report extensive computational results on a large set of benchmark instances. The same exact algorithm is also tested on classical CARP benchmark sets and is shown to improve upon the best known exact algorithms for the CARP.