(2) Determine the cost of each resealing

operation.

criterion used to select an alternative must evalu-

(3) Determine the present worth of the re-

ate that alternative over a future time period. This

sealing costs by using the following formula:

analysis is usually termed a "life-cycle cost analy-

PW = R*[1.0/(1+i)n]

sis." Short term repairs that may be inexpensive

initially may end up costing more than another

where

alternative after repairs to the alternative have

PW = the present worth.

been made several times over the life of the

i = the annual interest rate.

pavement. The life-cycle cost analysis clearly

R = the cost of each sealant installation.

shows which alternative will give the least cost

n = the number of years from the present

over the life of the pavement. After completion of

time until resealing will be required again.

life-cycle costing, one should consider the impact

(4)

Repeat the formula for every sealing pe-

of each alternative on interference with mission

riod and sum the total present worth of each

operations.

alternative.

cost analysis, certain data are required for each of

ternative with the least present worth. This cost

the sealing alternatives. The data required

indicates the alternative that would cost the least

includes:

over the entire life expressed as dollars at today's

value. In this manner, a relatively expensive

(1) Unit cost of the sealant in place. This

sealant with long life may be more economical

can be broken into material cost and installation.

over the life of the pavement than a series of less

(2) The expected remaining life, in years, of

costly procedures. The decision on whether this

the pavement feature being resealed before major

higher initial investment is affordable must be

rehabilitation or abandonment is scheduled.

made separately, considering more than just life-

(3) The expected lives of the sealants are

cycle cost.

being considered as alternatives. Because some

installations may have adequate data on the service

life of sealants while others may not, the major

command engineers must have input in setting life

before major rehabilitation in the form of an

expectancy levels for a life-cycle cost analysis

overlay is performed. The interest rate for this

compatible with paragraph (2) as mentioned.

period is estimated to be 12 percent a year.

Inflation is not considered in this initial analysis.

(4) The interest rate in effect over the life of

There are two alternatives for sealing the pave-

the pavement must be selected. Depending upon

ment. The two alternatives are:

the economic climate, this value may be very

(1) Seal every 3 years at a cost of

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.60 perdifficult to estimate for any time in the future.

linear foot.

(5) The use of inflation in a life-cycle cost

(2) Use a seal with a life expectancy of 15

analysis is somewhat controversial; however, it

years at a cost of .00 per linear foot.

should be used by the installation when evaluating

alternatives. One method to obtain inflation is to

will be six costs of

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.60 per foot. The joints mustuse the expected future cost of materials and

be resealed before the overlay in year 16 so that

labor.

there are five time increments. For the second

alternative, there will be one initial payment at

performed by completing the following steps:

time zero and one resealing job before the overlay

(1) Determine how many times the

with the least expensive method. The computation

pavement must be resealed over the analysis

of the present worth for both alternatives is as

period.

follows: