ETL 1110-1-189
14 Feb 03
5.0 Life Cycle Cost Analysis
A detailed cost analysis should be performed to determine if the geogrid-reinforced pavement
design is justified. The cost of the geosynthetic-reinforced pavement section should be
compared to the cost of an unreinforced pavement section. A direct cost comparison based upon
material savings alone, however, does not include the indirect benefits of using geogrid
reinforcement. These indirect benefits include increased site mobility, improved ease of
construction, reduced haul costs for additional aggregate, and an improved ability to meet
compaction requirements over soft subgrades. These indirect benefits may compensate for slight
increases in material costs. An appropriate cost analysis procedure should consist of the
following steps as adapted from Berg et al. (2000):
1. Compute the initial material and construction costs for the pavement.
a. Compute costs for the unreinforced design.
b. Compute costs for each reinforced design option.
c. Compute costs for other alternatives.
2. Compute the life-cycle costs for the pavement.
a. Compute the life-cycle costs for the unreinforced pavement.
b. Compute the life-cycle costs for the reinforced design options.
c. Compute the life-cycle costs for other alternatives.
3. List the benefits that are difficult to quantify in terms of dollar amounts or the "hidden"
benefits.
4. Compare the initial construction costs, the life-cycle costs, and the "hidden" benefits for
each design alternative. Select the alternative that meets the objectives of the project at the
minimum cost. The value of "hidden" benefits must be considered and can be used to
distinguish between alternatives with similar financial requirements.
6.0 Construction of Geosynthetic-Reinforced Pavements
The construction of geosynthetic-reinforced pavements may require modifications to
standard road construction procedures, primarily to prevent damage to the geosynthetics.
Pavement construction over very soft subgrades requires special consideration to both protect the
geosynthetics and prevent overloading by construction traffic. The following sections describe
recommended procedures for accomplishing pavement construction with geosynthetic
reinforcement.
6.1 Geotextile Installation
Prior to installation of the geotextile, the site should be cleared, grubbed, and
excavated to the design grade unless the subgrade CBR is less than 2.0. If the subgrade soil
CBR is 2.0 or greater, the subgrade should be compacted to identify any unsuitable materials
that may damage the geotextile. Unsuitable items such as stumps, roots, etc. should be
removed if practical. If the subgrade soil CBR is less than 2.0, surface materials such as
vegetation and root mats may be advantageous and should not be removed. Small sections of
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