Calculating the Lifecycle Costs of Different Pavement Structures Applicable to Mozambican Conditions
Jolanda P. Prozzi
Research Associate, Center for Transportation Research
The University of Texas at Austin, 3208 Red River, Austin, TX 78705
Tel.: (512) 232 3079, Fax: (512) 232 3070,
Jorge A. Prozzi
The University of Texas, ECJ 6.112, Austin, TX 78712
Tel.: (512) 232-3488, Fax: (512) 475-8744,
With the support from the World Bank, Mozambique is investing in the rehabilitation and improvement of its road infrastructure. In the past, extensive use has been made of foreign engineers and contractors that were not necessarily familiar with Mozambican conditions and materials. This has been aggravated by the increased use of marginal materials that do not always meet current specifications but have been used due to the lack of suitable economical base and subbase materials. Pavement design and rehabilitation methods being used worldwide are being applied. Some of them are not necessarily applicable to Mozambican conditions resulting in the implementation of inappropriate designs and construction techniques leading to poor performance.
The treatment of these marginal materials with stabilizers or modifiers is currently common practice in the country. However, the selection of modifier type and content necessary for a pavement to withstand the traffic loading and the environmental condition is often a grey area for practitioners. Furthermore, laboratory tests of materials do not always represent the actual performance of pavements in the field.
Field and laboratory testing by means of model and full scale accelerated pavement testing (APT) is considered to be the most cost effective and appropriate testing technique to simulate the material properties and to evaluate the behaviour of different pavement structures in a relatively short period of time. Small scale APT in the laboratory using the MMLS3 has been carried out to allow a comparison, in terms of pavement behaviour and performance, between alternative materials under the same environmental and subgrade conditions. These tests will be followed by full scale APT evaluation of selected field sections (with MLS10) to confirm laboratory behaviour and thus actual performance. On the basis of this performance, design and construction methods will be developed and recommended to include calculation of lifecycle costs for comparison of different designs. This presentation will focus on the lifecycle costs analysis aimed at determining the optimum pavement design strategy to be selected.
PRESENTERS’ QUESTIONS: We would like to receive comments, suggestions, and feedback from the meeting's attendees on the following matters:
1- Given the tremendous uncertainty associated with some of the key inputs required for the lifecycle cost analysis (i.e., traffic, cost of construction materials, rehabilitation techniques, road user costs, etc.) what are the best techniques for analyzing the costs and benefits?
2- How do analysts go about obtaining the basic information and what to be done in cases where data do not exist?
PRESENTERS’ STATEMENT: This work is still in progress, and has not been submitted for presentation or publication at another meeting.