| Spread
Sheet Demonstration of MPT Cost Savings |
Below is an example
cost analysis of the present and new system of maintenance
of 100,000 power pole population.
Note: These costs have doubled
from the 2008 figures below.
PRESENT SYSTEM
Note: It has been assumed
that 5% of poles fail the present pole inspection criteria
and 25% of failed poles need to be replaced rather than
reinstated.
| Cost of pole inspection
and pole treatment: |
100,000 x $25 |
= |
$2,500,000 |
| Cost of reinstatement
of 75% of failed poles: |
100,000 x 0.05 x 0.75 x $500 |
= |
$1,875,000 |
| Cost of replacement of 25% of failed
poles: |
100,000 x 0.05 x 0.25 x $2,500 |
= |
$3,125,000 |
| Total cost of present system |
|
= |
$7,500,000 |
NEW SYSTEM
Using mechanical proof load
test instead of the present pole inspection and chemical
treatment of poles.
Note: It has been assumed
that 90% of all poles is tested mechanically instead of
the present pole inspection. Also, it is assumed that at
least 50% of poles currently failed by the present pole
inspection will be saved by mechanical test, i.e. 2.5% of
all poles tested mechanically will fail (instead of 5% failed
by the present pole inspection).
| Cost of present inspection
and treatment (to 10% of all poles): |
0.10 x 100,000 x $25 |
= |
$250,000 |
| Cost of mechanical test: (to 90% of
all poles): |
0.90 x 100,000 x $20 |
= |
$1,800,000 |
| Cost of pole reinstatement of 75% of
poles failed by present system (to 10% of all poles): |
100,000 x 0.10 x 0.05 x 0.75 x $500 |
= |
$187,500 |
| Cost of reinstatement of 75% of poles
failed by new system (to 90% of all poles): |
100,000 x 0.90 x 0.025 x 0.75 x $500 |
= |
$843,750 |
| Cost of pole replacement of 25% of
poles failed by present system (to 10% of all poles): |
100,000 x 0.10 x 0.05 x 0.25 x $2,500 |
= |
$312,500 |
| Cost of replacement of 25% of poles
failed by new system (to 90% of all poles): |
100,000 x 0.90 x 0.025 x 0.25 x $2,500 |
= |
$1,406,250 |
| Total cost of new system |
|
= |
$4,800,000 |
| Total savings due to replacement
of present pole inspection and treatment with mechanical
proof load test: |
|
= |
$2,700,000 |
NEW SYSTEM
Using mechanical proof load
test in addition to present pole inspection and chemical
treatment.
Note: It has been assumed
that 90% of all poles is tested mechanically in addition
to the present pole inspection. Also, it is assumed that
at least 50% of poles currently failed by the present pole
inspection will be saved by the mechanical test, i.e. 2.5%
of all poles tested mechanically will fail (instead of 5%
failed by the present pole inspection).
| Cost of present inspection
and treatment (to all poles): |
100,000 x $25 |
= |
$250,000 |
| Additional cost of mechanical test:
(to 90% of all poles): |
0.90 x 100,000 x $20 |
= |
$1,800,000 |
| Cost of reinstatement of 75% of poles
failed by present system (to 10% of all poles): |
100,000 x 0.10 x 0.05 x 0.75 x $500 |
= |
$843,750 |
| Cost of replacement of 25% of poles
failed by present system (to 10% of all poles): |
100,000 x 0.10 x 0.05 x 0.25 x $2,500 |
= |
$312,500 |
| Cost of replacement of 25% of poles
failed by new system (to 90% of all poles): |
100,000 x 0.90 x 0.025 x 0.25 x $2,500 |
= |
$1,406,250 |
| Total cost of new system |
|
= |
$7,050,000 |
| Total savings due to addition
of mechanical proof load test to present pole inspection
and treatment: |
|
= |
$450,000 |
CONCLUSIONS
Present methods of pole inspection
are approximate and generally subjective. As a result they
reject many serviceable poles and fail to identify some
dangerous poles.
The new Deuar system, based
on the most objective and accurate direct measurement of
the needed pole strength, saves poles from premature replacement
and pinpoints all dangerous poles.
It provides not only a more
cost effective mainenance of power pole assets but at the
same time increases the safety to the public and utility
personnel.
Analysis by independent structural
engineers has validated the new system and vast experience
and statistics clearly indicate that the risk of pole failure
prior to the next inspection is many times less than the
present risk.
Advanced Present Value
Analysis of Mechanically Tested Poles
1. Introduction
The ECTEST14 computer program
can accurately check whether it is economic to mechanically
test any particular condemned or suspect pole or a group
of such poles with some average features.
The ECTEST12 computer program
can additionally make any economic comparison between the
reinstated pole and mechanically tested pole, which may
still be reinstated after its failure.
The ECTEST11 computer program
can check whether it is economic to mechanically test all
poles or any group of sericeable poles.
2. Method Description
The advanced present value
analysis incorporates probabilistic enhancements which allow
for reasonable coverage of the number of uncertain economic
data, such as future discount rate, etc.
The programs ask a number of
questions about the pole costs, serviceable life, discount
rate as well as corresponding standard deviations for all
data if the probabilistic analysis is required.
After the requested information
is input, the ECTST14 and ECTEST11 programs calculate the
present value of the maintenance of a new pole and mechanically
tested pole, net savings or losses to utility per one pole,
and minimum savings (or maximum losses) per one pole guaranteed
with the chosen confidence level if the probabilistic analysis
is required. The ECTEST12 program calculates additionally
the present value of the maintenance of a reinstated pole
and mechanically tested pole, which may still be reinstated
after it failure.
The economic analysis is run
until the present value of the successive pole replacement
is less than one dollar. This condition enables very accurate
and explicit comparison between the analysed pole management
options.
3. Assumptions
As in any analysis some assumptions
had to be adopted of which the most imporant are:
a) The additional
cost of mechanical testing of one pole, resulting from the
necessity of temporary supporting of some failed poles,
is calculated as $50.00 * (100 - PPS) / PPS
where: 50.00 = average cost of temporary
supporting of one pole (assuming that approximately half
of the failed poles does not require any temporary support)
and PPS = percentage of poles saved by the mechanical test
from replacement
b) All the
time data are input in full years and within the economic
analysis all the time values are rounded up to a full number
of the pole inspection cycles.
|
