This study attempts to investigate the cost of Horizontal Directional Drilling (HDD) and open-cut construction methods for the installation of pressure waterlines in Nairobi, Kenya. The urban areas in developing countries (including Nairobi) attract immigrants from the surrounding rural areas creating very densely populated and congested areas. The streets are very congested with pedestrian and vehicular traffic. The traditional open method in these countries relies more on labor force than equipment. Consequently, open cut causes significant disturbance for lengthy period of time to residents and business. This environment makes the need for trenchless technology paramount. Usually the contractor who is involved in the first trenchless project in the country tries to amortize the cost of the trenchless system through this project. Usually the engineer resorts to trenchless technology only in most difficult situations when open cut cannot be employed and tries to limit the length of the trenchless part only to the difficult portions; as a result, the cost per linear meter increases significantly. The risks are usually high on the first job and the experience with the new technology is low, which also increases the project mark up and cost. Usually the above-cited difficulties stifle the introduction of trenchless technology to these areas. The paper attempts to compare the cost of HDD and open cut for the installation of 1000m long of 30cm in diameter waterlines underneath the busy streets of Nairobi, Kenya a few years after the introduction of HDD to Kenya. The cost analysis indicated that HDD is about 12.5% more expensive than open cut.
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