User cost savings in eliminating pavement excavations through employing trenchless technologies

When a pipeline is installed under flexible pavement structures using open excavation and fill methods, the excavation can result in premature pavement deterioration due to difficulties associated with trench site restoration and soil and asphalt compaction. In developed areas, trenchless construction methods have become a popular alternative to open trench excavation because of reduced surface disruptions and reinstatement costs, a shorter construction period, and significantly reduced traffic delay costs associated with construction by saving time in construction operations. This paper summarizes a recent study that examined how pipeline installations on 1- and 7-year-old Ontario municipal collectors and minor arterial roads impact the 30-year life cycle of a pavement in terms of performance, future maintenance costs, and user-delay costs. Study results indicated that (1) approximately 30% reduction in pavement life can be expected once an excavation is made in a road; (2) increased maintenance and rehabilitation costs for excavating 1-year-old pavement were determined to be approximately Can$146/m 2 , and the costs for excavating 7-year-old pavement vary from Can$85 to $140/m 2 ; and (3) the use of trenchless technology with good construction practices has the potential to significantly reduce road maintenance and rehabilitation costs and user-delay costs.Key words: pavement performance, open excavation, trenchless technologies, user-delay costs.