PAVEMENT PRESERVATION
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Transcript PAVEMENT PRESERVATION
Life-Cycle Costing for
Innovative Pavement
Preservation Treatments
How to Know if the Investment is Worth It
Overlay Ch art
Altern ative A/B Co mp arisio n
David Hein, P.Eng.
Principal Engineer
Vice-President, Transportation
.088
Al tern ati ve A P res ent W o rth
.066
.044
.022
Al tern ati ve B P res ent W o rth
.000
$25,000 .00
$75,000 .00
$125 ,00 0.00
$175 ,00 0.00
$225 ,00 0.00
Why Pavement Preservation?
Critical component of system preservation
Preserves the public’s Investment
Extends pavement service life
Saves $$$$
Expanding the Realm of Possibility
Traditional Approach
Allows deterioration to fair to
poor conditions
Ride quality and structural
Rehabilitation strategy repairs
damage
Clearly reactive, time consuming
and costly
Expanding the Realm of Possibility
Proactive Approach
Applies low-cost preventive treatments
5 to 7 year life
Timing is critical
Good Condition
NO structural damage
Expanding the Realm of Possibility
How to Select the Appropriate
Treatment and Timing?
Pavement Surface/Type
Asphalt
Concrete
Exposed
PCC
SurfacedTreated
Other Features
GravelSurfaced
•Drainage improvements
•Vegetation control
•Etc.
Repeat for other pavement types and features
Trigger Values and Timing of Maintenance
Distress type, severity and density
• Roughness
• Rutting
• Alligator cracking
• Flushing, etc.
Management Aspects
Available Treatments
• Hot and cold mix patching
• Spray patching (manual chip seal)
• Routing and sealing of cracks
• Micro-surfacing
• Etc.
Treatment Selection
• Pavement/maintenance
management system
• Other planning tools
Technical Aspects
• Roadway functional type
Treatment
Implementation
• Geographical area/environment
• Size of municipality
Expanding the Realm of Possibility
Better Informed Decisions
Right treatment for the Right pavement at the Right time
•
What is the condition
of the existing
pavement
•
What is the expected
performance of the
pavement
•
How will different
treatments affect this
performance
Expanding the Realm of Possibility
Life-Cycle Cost Analysis Method
Analysis Period
Performance
Period
Remaining
Life
Condition
Cost
Remaining
Value
Time
Expanding the Realm of Possibility
LCCA Framework
Input variables and factors
Analysis period
Treatment performance
Which costs to include (user costs?)
Discount rate
Residual or salvage value
Analysis methods
Economic analysis or formula
Computational approach (deterministic vs.
probabilistic)
Expanding the Realm of Possibility
Analysis Period
Time
period used for comparing the costs of
alternative design strategies
In
general, analysis period
Should be long enough to reflect long-term
cost differences of alternative designs
Should be long enough to incorporate at
least one rehabilitation
9
Expanding the Realm of Possibility
Conventional Performance
PCR
New
Construction
Overlay 1
B0
Overlay 2
BOL1
BOL2
Overlay 3
BOL3
Lower Benefit Limit PCR
Age
Analysis Period
C0
COL1
COL2
COL3
S
Expanding the Realm of Possibility
Performance – 1 PM Treatment
PCR
New
Construction
Preventive
Maintenance
Treatment 1
B0
Overlay 1
BP1
Overlay 2
BOL1
BOL2
Lower Benefit Limit PCR
Age
Analysis Period
C0
COL1
CP1
COL2
S
Expanding the Realm of Possibility
Establishing Service Life
For each design alternative, establish initial
service life and subsequent M&R activities
covering analysis period
Based on historical performance (survival
analysis)
Engineering judgment for project-specific
factors:
• Environment/subgrade
• Traffic loadings
• Use of new materials/technologies
Expanding the Realm of Possibility
Treatment Performance
Pavement performance curve
Pavement Condition Rating
100
Preventive
Maintenance
Change due to a preventive
maintenance treatment
70
Maintenance and
Rehabilitation
Minimum recommended condition
Benefit
Reconstruction
0
0
Extended pavement life due
to preventive maintenance
5
10
Pavement Age, years
15
Expanding the Realm of Possibility
Goal of Prediction Modeling
Predicted performance
A
B
Pavement Condition
Remaining service life
Minimum acceptable service
level
Past performance
Now
Now +2
Pavement Age, years
Now +5
Expanding the Realm of Possibility
Pavement Condition Needs
Pavement surface condition prior to PM
treatment
Condition ratings immediately before treatment
and since treatment
Other information that may affect PM treatment
performance:
Pavement type
Age
Traffic
Subgrade
Expanding the Realm of Possibility
Thin Overlay Flexible
100
90
PCR
80
70
10VIN328R, 6,000 ESALs/yr - Nonwarranty
9BRO131R, 11,000 ESALs/yr - Nonwarranty
3ASD604R, 11,000 ESALs/yr - Warranty
3ASD095R, 11,000 ESALs/yr - Warranty
9SCI348R, 18,000 ESALs/yr - Warranty
3CRA103R, 18,000 ESALs/yr - Warranty
60
50
-2
-1
0
1
2
3
4
5
6
7
Year
Expanding the Realm of Possibility
Microsurfacing – Urban/Flex
100
90
PCR
80
70
8GRE042R, 85,000 ESALs/yr - Warranty
2OTT163R, 122,000 ESALs/yr - Warranty
4STA093R, 143,000 ESALs/yr - Nonwarranty
60
8WAR048R, 146,000 ESALs/yr - Nonwarranty
2OTT163R, 149,000 ESALs/yr - Warranty
2WOO023R, 1128,000 ESALs/yr - Warranty
50
-2
-1
0
1
2
3
4
5
6
7
Year
Expanding the Realm of Possibility
Ultra Thin Bonded Wearing
Course– Composite
100
90
PCR
80
70
8BUT177R, 29,000 ESALs/yr - Nonwarranty
3RIC430R, 39,000 ESALs/yr - Nonwarranty
60
11TUS039R, 195,000 ESALs/yr - Warranty
8HAM127R, 226,000 ESALs/yr - Nonwarranty
5PER345R, 61,000 ESALs/yr - Warranty
50
-2
-1
0
1
2
3
4
5
6
7
Year
Expanding the Realm of Possibility
Chip Seal Flexible Pavement
100
y = -3.3798x + 92.25
R2 = 0.4371
90
80
PCR
5.0 yrs
6.5 yrs
70
8.0 yrs
60
n = 17
50
-2
0
2
4
6
8
10
12
Age, Years
Expanding the Realm of Possibility
Thin Overlay Repairs/Flex
100
y = -3.4284x + 95.424
R2 = 0.6111
90
80
PCR
6.0 yrs
7.5 yrs
70
9.0 yrs
60
n = 123
50
-2
0
2
4
6
8
10
12
Age, Years
Expanding the Realm of Possibility
Microsurfacing - Composite
100
90
PCR
80
70
60
n = 23
50
-2
0
2
4
6
8
10
12
Age, Years
Expanding the Realm of Possibility
Conventional Overlay
100
y = -3.3558x + 95.68
R2 = 0.6093
90
PCR
80
7.5 yrs
70
9.0 yrs
10.5 yrs
60
n = 48
50
-2
0
2
4
6
8
10
12
Age, Years
Expanding the Realm of Possibility
Control - New Flexible
100
y = -3.1714x + 97.07
R2 = 0.467
90
PCR
80
8.5 yrs
70
10.5 yrs
11.5 yrs
60
n = 86
50
0
2
4
6
8
10
12
Age, Years
Expanding the Realm of Possibility
PM Treatment
Chip seal
Condition
Prior to
Treatment
Pavement
Type
Fair
All
Good
Treatment Age at
Terminal PCR,
Years
Number
of
projects, n
R
-2.0762 AGE + 89.954 *
17
0.32
7.0*
All
-3.3798 AGE + 92.25
17
0.44
All
All
-2.7 AGE + 91.107*
34
Fair
All
-2.6482 AGE + 91.857*
Regression Model
2
75
70
65
5.0
6.5
8.0
0.37
5.5*
7.5*
19
0.28
6.5*
8.0*
2
Microsurfacing
Double
Microsurfacing
NovaChip
®
Smoothseal
Thin Overlay
without Repairs
Thin Overlay
with Repairs
Good
All
-0.436 AGE -0.4833 AGE +
92.179
19
0.24
5.5
6.5
All
All
-2.552 AGE + 92.438
38
0.28
7.0*
8.5*
All
All
Insufficient long-term data
17
All
All
-2.9966 AGE + 96.766
9
0.46
7.5
9.0
All
All
Insufficient long-term data
23
Fair
Flexible
-3.4284 AGE + 95.424
123
0.61
6.0
7.5
9.0
Good
Flexible
-2.8179 AGE + 95.365
102
0.53
7.0
9.0
10.5
Fair
Composite
-3.1076 AGE + 92.817
75
0.49
5.5
7.5
9.0
Good
Composite
-3.3702 AGE + 96.147
28
0.60
6.5
8.0
9.5
Fair
Flexible
-2.4205 AGE + 96.012
26
0.41
8.5
10.5
Good
Flexible
-3.1411 AGE + 94.197*
12
0.53
6.0*
7.5*
9.0*
Fair
Composite
-3.4486 AGE + 98.882
12
0.76
7.0
8.5
10.0
Good
Composite
-2.6185 AGE + 98.927*
7
7.5
0.83 9.0*
11.0*of Possibility
Expanding
the Realm
Type
Traffic
Number
of
projects, n
R
0.0231 AGE - 3.5049 AGE +
97.42
102
Urban
-3.1942 AGE + 96.384
Priority
General
Priority
Class
Regression Model
2
Age at Terminal
PCR, Years
70
65
60
0.69
8.5
10.0
11.5
41
0.68
8.5
10.0
11.5
-2.6528 AGE + 95.06
105
0.48
9.5
11.5
-3.3558 AGE + 95.68
48
0.61
7.5
9.0
10.5
Urban
0.046 AGE - 3.9254 AGE +
96.297
106
0.75
7.5
9.0
10.5
Priority
-3.0532 AGE + 93.969
196
0.49
8.0
9.5
11.0
General
-1.3198 AGE + 97.371*
23
0.67
*
Urban
-3.3442 AGE + 96.076
22
0.67
8.0
9.5
11.0
Priority
-2.4868 AGE + 92.965
25
0.56
9.5
11.5
Urban
-2.9145 AGE + 94.686
39
0.52
8.5
10.5
12.0
High
Priority
0.0543 AGE - 4.1665 AGE +
96.709
93
0.59
7.0
8.5
10.5
Low
Medium
Medium
High
General
Urban
-3.8854 AGE + 98.107
33
0.69
7.5
8.5
10.0
Priority
-3.1714 AGE + 97.07
86
0.47
8.5
10.5
11.5
2
General
Low
Overlay without
repairs
Medium
2
High
Low
Overlay with
repairs
Medium
2
New flexible
pavement
Expanding the Realm of Possibility
Agency Costs
Initial costs
All upkeep costs
Residual or salvage value (negative cost)
When comparing alternatives, only cost
items that differ need to be included
Examples of similar costs:
Shoulder construction
Routine maintenance
Subgrade preparation
Engineering and administrative costs
Expanding the Realm of Possibility
User Costs (Not currently
considered in Indiana)
Vehicle operating costs (VOC)
Depreciation
Fuel, oil
Maintenance and repair
Roadway-related vehicle depreciation
Time delay
Safety costs (property, injury, life)
Environmental cost (emissions, noise)
Discomfort costs
Expanding the Realm of Possibility
Components of User Costs
User costs include
Delays
Vehicle operating costs (VOC)
Crash costs
Expanding the Realm of Possibility
User Cost Influences
User costs are directly related to:
Current and future traffic demand
Facility capacity
Timing, duration, and frequency of work
zone restrictions
Detour route
Expanding the Realm of Possibility
Work Zone Capacity
When work zone capacity exceeds demand
User costs are manageable
More an inconvenience than cost
When demand exceeds work zone capacity
Conditions become forced flow
Queuing costs can account for 95 percent
of user costs
Expanding the Realm of Possibility
User Delay Costs
Crash costs between competing alternatives
should not vary considerably
Vehicle operating costs will vary depending
on vehicle type
Delay costs (ie, value of time) are extremely
controversial
Expanding the Realm of Possibility
Value of Time
FHWA recommended value of time
$ Value Per Vehicle Hour
Vehicle Class
Passenger Vehicles
Single-Unit Trucks
Combination Trucks
Value
Range
11.58
10 to 13
18.54
17 to 20
22.31
21 to 24
Expanding the Realm of Possibility
Discount Rate
interest rate (%) inflation rate (%)
discount rate (%)
1 inflation rate (%)
100
discount rate (%) interest rate (%) inflation rate (%)
Discount rate is a function of interest rate and
inflation rate
The use of current dollars and real discount
rate eliminates the effect of inflation
Expanding the Realm of Possibility
How to Get Discount Rate?
Analysis of long-term trends in interest rates
and associated inflation rates
Office of Economic Policy, is in the position to
recommend “social discount rate”
FHWA recommendation is 3% to 5%
Expanding the Realm of Possibility
Salvage value
1. Residual value
2.
Net value from recycling of the
pavement
Remaining life
Remaining life of the pavement at the
end of the analysis period
Expanding the Realm of Possibility
Remaining Life
A
Serviceable life = x % of Treatment cost
x % of L
B
Treatment
Cost
L
Analysis period
Expanding the Realm of Possibility
Analysis Methods
Economic Analysis (Life-Cycle Cost)
1
NPV InitialCost FutureCost *
n
1
i
2
NPV = Net Present Value, $/m
n = Time of future cost, years
i = Discount rate
Formula Analysis (Benefit/Cost Ratio)
Benefit
= Area under Performance Curve (PCR
vs. Age)
Cost
= NPV
Expanding the Realm of Possibility
Example Deterministic LCCA
Rehabilitation
Without Preventive Maintenance
$60,000
2000
01
02
03
04
2005
06
07
08
09
2010
11
12
13
14
2015
16
Year
Sum: $31,610
(Present value)
With Preventive Maintenance
2000
01
02
$1,040
Crack sealing
Crack sealing
$1,100
$1,500
03
04
2005
06
07
Rehabilitation
$60,000
3 years
08
09
2010
11
12
13
14
2015
16
Year
$1,120
$26,540
Sum: $28,700
(Present value)
Savings = $ 2,910/km ~ 10 percent
Expanding the Realm of Possibility
Example Deterministic LCCA
CONVENTIONAL
YEAR
DESCRIPTION
n
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Reconstruct (Flexible)
CAPITAL
COST
DISCOUNT RATE:
M&R
NET CASH
COST
FLOW
$418,407
Rout and Seal
$868
Mill & Patch, R & S
$15,281
Mill & Patch, R & S
$22,054
Mill & Overlay
$194,244
R&S
$1,240
Mill & Patch, R & S
$22,798
Mill & Patch, R & S
$28,827
Mill & Overlay
$97,161
Salvage Value
-$82,213
NET PRESENT VALUE ($ / 2 Lane-km)
$418,407
$0
$0
$868
$0
$0
$0
$15,281
$0
$0
$0
$22,054
$0
$0
$0
$194,244
$0
$0
$1,240
$0
$0
$0
$22,798
$0
$0
$28,827
$0
$0
$97,161
$0
-$82,213
5.0%
PRESENT
VALUE
$418,407
$0
$0
$750
$0
$0
$0
$10,860
$0
$0
$0
$12,895
$0
$0
$0
$93,435
$0
$0
$515
$0
$0
$0
$7,794
$0
$0
$8,513
$0
$0
$24,785
$0
-$19,022
$558,930
PREVENTIVE MAINTENANCE
YEAR
DESCRIPTION
n
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Reconstruct (Flexible)
CAPITAL
COST
DISCOUNT RATE:
M&R
NET CASH
COST
FLOW
$418,407
Rout and Seal
$868
Mill & Patch, R & S
$22,054
Microsurface
$22,500
Mill & Patch, R & S
$22,054
Mill & Overlay
$194,244
R&S
$1,240
Microsurface
Mill & Patch, R & S
Salvage Value
$22,500
$22,054
-$14,942
NET PRESENT VALUE ($ / 2 Lane-km)
$418,407
$0
$0
$868
$0
$0
$0
$22,054
$0
$0
$22,500
$0
$0
$22,054
$0
$0
$0
$0
$194,244
$0
$0
$0
$1,240
$0
$0
$0
$22,500
$0
$0
$22,054
-$14,942
5.0%
PRESENT
VALUE
$418,407
$0
$0
$750
$0
$0
$0
$15,673
$0
$0
$13,813
$0
$0
$11,696
$0
$0
$0
$0
$80,712
$0
$0
$0
$424
$0
$0
$0
$6,328
$0
$0
$5,358
-$3,457
$549,704
Expanding the Realm of Possibility
Cost Streams and Savings
Cost (1000-$)
100
50
0
3
7
11
15
18
22
25
28
30
-50
Conventional
Year
Preventive Maintenance
NPW Conventional = $140,523
NPW Preventive Maintenance = $ 131,297
Net Savings per two lane-km = $ 9,226 - (~7 percent)
Expanding the Realm of Possibility
Larger Scale Evaluation
Analysis of the cost of performing various
treatments (typical costs and variability)
Cost-effectiveness/cost-benefit of individual PM
treatments
Evaluation of applicability of PM treatments, for
roadway classes, age and surface condition
Expanding the Realm of Possibility
Treatment Type:
Condition:
Pavement Type:
Priority Class:
Traffic Level:
NovaChip
Fair
Flexible
Priority
High
A
New Pavement Function:
Treatment Function:
Overlay Function:
Form:
Treatment
PCR Prior to Treatment:
Age at Treatment:
Treatment Life:
PCR Prior to Overlay:
Age at 1st Overlay:
1st Overlay Life:
Age at 2nd Overlay:
2nd Overlay Life:
Remaining Life:
Benefit:
Control
75
8.0
8.0
70
17.0
9.5
27.5
9.5
2.0
1098
PCR Prior to Overlay:
Age at 1st Overlay:
1st Overlay Life:
Age at 2nd Overlay:
2nd Overlay Life:
Age at 3rd Overlay:
3rd Overlay Life:
Remaining Life:
C
97.07
96.766
93.969
Costs
70
9.5
9.5
20.0
9.5
30.5
9.5
5.0
Treatment:
1st Overlay:
2nd Overlay:
3rd Overlay:
Salvage Value:
$
$
$
$
$
3.86
9.40
10.40
10.40
2.19
Benefit: 1058
Age Extension Due to Treatment:
Age Extension per Unit Cost:
7.5
1.9
50
45
40
35
30
25
20
15
10
5
0
70
Benefit/Cost Ratio, per $
Net Present Value, $
B
0
-3.1714
0
-2.9966
0
-3.0532
A x2 + B x + C
60
50
40
30
20
10
0
0
1
2
3
4
5
6
Discount Rate, %
0
1
2
3
4
5
6
Discount Rate, %
Legend:
Initial Cost: $10.00
Control section
Initial Cost: $10.00
Treatment section
Initial Cost: $15.00
Control section
Initial Cost: $15.00
Treatment section
Initial Cost: $20.00
Control section
Initial Cost: $20.00
Treatment section
Results @ 4% Discount Rate and $15.00 Initial
Construction Costs
Treatment
Control
Better?
LCC Costs: $ 25.63 $ 27.98 Treatment
Benefit/Costs:
42.86
37.80
Treatment
Expanding the Realm of Possibility
Treatment Type:
Condition:
Pavement Type:
Priority Class:
Traffic Level:
Microsurfacing
Good
Flexible
Priority
Medium
A
New Pavement Function:
Treatment Function:
Overlay Function:
Form:
Treatment
PCR Prior to Treatment:
Age at Treatment:
Treatment Life:
PCR Prior to Overlay:
Age at 1st Overlay:
1st Overlay Life:
Age at 2nd Overlay:
2nd Overlay Life:
Remaining Life:
Benefit:
Control
85
5.0
6.5
70
12.5
11.5
25.0
11.5
1.5
1085
PCR Prior to Overlay:
Age at 1st Overlay:
1st Overlay Life:
Age at 2nd Overlay:
2nd Overlay Life:
Age at 3rd Overlay:
3rd Overlay Life:
Remaining Life:
C
97.07
92.179
92.965
Costs
70
9.5
11.5
22.0
11.5
34.5
11.5
11.0
Treatment:
1st Overlay:
2nd Overlay:
3rd Overlay:
Salvage Value:
$
$
$
$
$
2.40
8.47
9.47
9.47
1.24
Benefit: 1011
Age Extension Due to Treatment:
Age Extension per Unit Cost:
3
1.3
70
Benefit/Cost Ratio, per $
45
Net Present Value, $
B
0
-3.1714
-0.436
-0.4833
0
-2.4868
A x2 + B x + C
40
35
30
25
20
15
10
5
0
60
50
40
30
20
10
0
0
1
2
3
4
5
6
Discount Rate, %
0
1
2
3
4
5
6
Discount Rate, %
Legend:
Initial Cost: $10.00
Control section
Initial Cost: $10.00
Treatment section
Initial Cost: $15.00
Control section
Initial Cost: $15.00
Treatment section
Initial Cost: $20.00
Control section
Initial Cost: $20.00
Treatment section
Results @ 4% Discount Rate and $15.00 Initial
Construction Costs
Treatment
Control
Better?
LCC Costs: $ 25.40 $ 24.98
Control
Benefit/Costs:
42.73
40.46
Treatment
Expanding the Realm of Possibility
Alternative Comparison – Chip
Seal, Microsurfacing and NovaChip
Discount Rate, %
3
4
PM Treatment
Effective?
Treatment
Chip Seal (very low
volume roadways only)
Chip Seal
Condition
Pavement Type
Traffic
Fair
Good
All (Mainly Flexible)
All (Mainly Flexible)
Low
Low
$ (2.65) $ (2.41) $ (2.23) $ (2.08) $ (1.95) $ (1.84) $
$ (0.55) $ (0.51) $ (0.50) $ (0.49) $ (0.48) $ (0.46) $
(1.73)
(0.45)
Yes
Yes
Single Microsurfacing
Single Microsurfacing
Single Microsurfacing
Single Microsurfacing
Fair
Good
Fair
Good
Flexible
Flexible
Composite
Composite
Low
Low
Low
Low
$ (1.52) $ (1.36) $ (1.25) $ (1.16) $ (1.09) $ (1.03) $ (0.98)
$ (0.12) $ (0.05) $ (0.01) $ 0.01 $ 0.02 $ 0.04 $ 0.05
$ (2.16) $ (1.83) $ (1.58) $ (1.40) $ (1.24) $ (1.11) $ (1.00)
$ 1.11 $ 1.12 $ 1.10 $ 1.07 $ 1.03 $ 1.00 $ 0.97
Yes
No
Yes
No
Double Microsurfacing
Double Microsurfacing
Double Microsurfacing
Double Microsurfacing
Double Microsurfacing
Double Microsurfacing
Double Microsurfacing
Double Microsurfacing
Fair
Good
Fair
Good
Fair
Good
Fair
Good
Flexible
Flexible
Flexible
Flexible
Composite
Composite
Composite
Composite
Low
Low
High
High
Low
Low
High
High
$ (0.57) $ (0.47) $ (0.42) $ (0.39) $
$ 0.83 $ 0.86 $ 0.87 $ 0.85 $
$ (1.00) $ (1.05) $ (1.05) $ (1.00) $
$ 1.45 $ 1.13 $ 0.94 $ 0.84 $
$ (1.21) $ (0.96) $ (0.79) $ (0.67) $
$ 2.06 $ 2.04 $ 1.98 $ 1.91 $
$ 0.23 $ (0.24) $ (0.50) $ (0.63) $
$ 3.89 $ 2.97 $ 2.42 $ 2.10 $
(0.34)
0.81
(0.79)
0.76
(0.44)
1.72
(0.68)
1.74
Yes
No
Yes
No
Yes
No
Yes
No
NovaChip
NovaChip
NovaChip
NovaChip
NovaChip
NovaChip
NovaChip
NovaChip
Fair
Good
Fair
Good
Fair
Good
Fair
Good
Flexible
Flexible
Flexible
Flexible
Composite
Composite
Composite
Composite
Low
Low
High
High
Low
Low
High
High
$ (1.62) $ (1.35) $ (1.14) $ (0.98) $ (0.84) $ (0.73) $ (0.63)
$ 0.48 $ 0.63 $ 0.73 $ 0.79 $ 0.84 $ 0.87 $ 0.91
$ (5.45) $ (4.69) $ (4.04) $ (3.49) $ (3.01) $ (2.61) $ (2.26)
$ 0.05 $ 0.07 $ 0.13 $ 0.22 $ 0.31 $ 0.40 $ 0.48
$ 1.06 $ 1.06 $ 1.01 $ 0.94 $ 0.86 $ 0.79 $ 0.72
$ 5.15 $ 4.83 $ 4.54 $ 4.28 $ 4.04 $ 3.83 $ 3.63
$ (1.76) $ (1.84) $ (1.83) $ (1.76) $ (1.67) $ (1.57) $ (1.46)
$ 1.89 $ 1.38 $ 1.10 $ 0.96 $ 0.89 $ 0.88 $ 0.88
Yes
No
Yes
No
No
No
Yes
No
Smoothseal
Smoothseal
Smoothseal
Smoothseal
Smoothseal
Smoothseal
Fair
Good
Fair
Good
Fair
Good
Flexible
Flexible
Flexible
Flexible
Composite
Composite
Low
Low
High
High
Low
Low
$
$
$
$
$
$
0
(3.21)
(1.11)
(6.75)
(1.25)
(3.38)
0.70
1
$
$
$
$
$
$
(2.83)
(0.90)
(5.86)
(1.15)
(2.87)
0.80
2
$
$
$
$
$
$
(2.52)
(0.74)
(5.10)
(1.02)
(2.46)
0.85
$
$
$
$
$
$
(2.27)
(0.62)
(4.44)
(0.87)
(2.13)
0.88
(0.37)
0.84
(0.94)
0.79
(0.58)
1.85
(0.68)
1.91
5
$
$
$
$
$
$
$
$
$ (2.05) $
$ (0.52) $
$ (3.87) $
$ (0.72) $
$ (1.86) $
Expanding
$ 0.89 $
(0.36)
0.82
(0.87)
0.77
(0.50)
1.78
(0.70)
1.80
6
$
$
$
$
$
$
$
$
(1.86) $ (1.69)
Yes
(0.43) $ (0.35)
Yes
(3.38) $ (2.96)
Yes
(0.57) $ (0.44)
Yes
(1.62) $ (1.42)
Yes
the
of Possibility
0.89Realm
$ 0.89
No
Double Microsurfacing
Double Microsurfacing
Double Microsurfacing
Good
Fair
Good
Composite
Composite
Composite
Low
High
High
$
$
$
2.06
0.23
3.89
$ 2.04 $ 1.98 $ 1.91 $ 1.85 $ 1.78 $ 1.72
$ (0.24) $ (0.50) $ (0.63) $ (0.68) $ (0.70) $ (0.68)
$ 2.97 $ 2.42 $ 2.10 $ 1.91 $ 1.80 $ 1.74
No
Yes
No
Alternative Comparison – Various
Thin Overlays
Flexible
Fair
NovaChip
Flexible
Good
NovaChip
Flexible
Fair
NovaChip
Flexible
Good
NovaChip
Composite
Fair
NovaChip
Composite
Good
NovaChip
Composite
Fair
NovaChip
Composite
Good
NovaChip
Treatment
Condition Pavement Type
Flexible
Fair
Smoothseal
Chip
Seal (very low
Flexible
Good
Smoothseal
volume
roadways only)
Fair
All (Mainly
Flexible)
Flexible
Fair
Smoothseal
Chip
Seal
Good
All (Mainly
Flexible)
Flexible
Good
Smoothseal
Single Microsurfacing
Fair
Flexible
Composite
Fair
Smoothseal
Single Microsurfacing
Good
Flexible
Composite
Good
Smoothseal
Single Microsurfacing
Fair
Composite
Composite
Fair
Smoothseal
Single Microsurfacing
Good
Composite
Composite
Good
Smoothseal
Double Microsurfacing
Fair
Flexible
Flexible
Fair
Repairs
without
OL
Thin
Double Microsurfacing
Good
Flexible
Flexible
Good
Repairs
without
OL
Thin
Double Microsurfacing
Fair
Flexible
Flexible
Fair
Repairs
without
OL
Thin
Double Microsurfacing
Good
Flexible
Flexible
Good
Repairs
without
OL
Thin
Double Microsurfacing
Fair
Composite
Composite
Fair
Repairs
without
OL
Thin
Double Microsurfacing
Good
Composite
Composite
Good
without Repairs
OLMicrosurfacing
Thin
Double
Fair
Composite
Fair
Repairs
without
OL
Thin
Double Microsurfacing
Good
Composite
Good
Thin OL without Repairs
NovaChip
Fair
Flexible
Fair
Thin OL with Repairs
NovaChip
Good
Flexible
NovaChip
Fair
Flexible
Good
Thin OL with Repairs
NovaChip
Good
Flexible
Fair
Thin OL with Repairs
NovaChip
Fair
Composite
Flexible
Good
Thin OL with Repairs
NovaChip
Good
Composite
Fair
Thin OL with Repairs
NovaChip
Fair
Composite
Good
Thin OL with Repairs
NovaChip
Good
Composite
Composite
Fair
Thin OL with Repairs
Composite
Good
Thin OL with Repairs
Smoothseal
Fair
Flexible
Smoothseal
Good
Flexible
Smoothseal
Fair
Flexible
Smoothseal
Good
Flexible
Smoothseal
Fair
Composite
Smoothseal
Good
Composite
Smoothseal
Fair
Composite
Smoothseal
Good
Composite
Low
Low
High
High
Low
Low
High
High
Traffic
Low
Low
High
Low
High
Low
Low
Low
Low
Low
High
Low
High
Low
Low
Low
Low
High
High
High
High
Low
Low
Low
Low
High
High
High
Low
Low
High
Low
High
Low
High
Low
High
Low
High
High
High
Low
Low
High
High
Low
Low
High
High
$ (1.62) $ (1.35) $ (1.14) $ (0.98) $ (0.84) $
$ 0.48 $ 0.63 $ 0.73 $ 0.79 $ 0.84 $
$ (5.45) $ (4.69) $ (4.04) $ (3.49) $ (3.01) $
$ 0.05 $ 0.07 $ 0.13 $ 0.22 $ 0.31 $
$ 1.06 $ 1.06 $ 1.01 $ 0.94 $ 0.86 $
$ 5.15 $ 4.83 $ 4.54 $ 4.28 $ 4.04 $
$ (1.76) $ (1.84) $ (1.83) $ (1.76) $ (1.67) $
Discount Rate, %
$ 1.89 $ 1.38 $ 1.10 $ 0.96 $ 0.89 $
0
1
2
3
4
$ (3.21) $ (2.83) $ (2.52) $ (2.27) $ (2.05) $
(0.52) $
(0.62) $ (1.95)
(0.74) $ (2.08)
(0.90) $ (2.23)
(1.11) $ (2.41)
$ (2.65)
(3.87) $
(4.44) $ (0.48)
(5.10) $ (0.49)
(5.86) $ (0.50)
(6.75) $ (0.51)
$ (0.55)
$
(0.87)
$
(1.02)
$
(1.15)
$
(1.25)
$
$ (1.52) $ (1.36) $ (1.25) $ (1.16) $ (0.72)
(1.09) $
$
$
(2.13)
$
(2.46)
$
(2.87)
$
(3.38)
$
$ (0.12) $ (0.05) $ (0.01) $ 0.01 $ (1.86)
0.02 $
$
$
0.89 $
$ (1.24)
0.88 $
$ (1.40)
0.85 $
$ (1.58)
0.80 $
$ (1.83)
0.70 $
$ (2.16)
$
$
(4.35)
$
(4.74)
$
(5.17)
$
(5.63)
$
(6.11)
$
$ 1.11 $ 1.12 $ 1.10 $ 1.07 $ 1.03 $
$ (2.46) $ (2.45) $ (2.35) $ (2.20) $ (2.02) $
$ (0.57) $ (0.47) $ (0.42) $ (0.39) $ (0.37) $
$
$ (1.36)
0.83 $
$ (1.14)
0.86 $
$ (0.98)
0.87 $
$ (0.86)
0.85 $
$ (0.76)
0.84 $
$
$
0.03 $
$
(0.09)
$
(0.23)
$
(0.41)
$
(0.66)
$
$ (1.00) $ (1.05) $ (1.05) $ (1.00) $ (0.94)
$
(1.55)
$
(1.77)
$
(2.02)
$
(2.30)
$
(2.60)
$
$ 1.45 $ 1.13 $ 0.94 $ 0.84 $ 0.79 $
$
1.28 $
$ (0.58)
1.30 $
$ (0.67)
1.36 $
$ (0.79)
1.47 $
$ (0.96)
1.67 $
$ (1.21)
$
$
(0.60)
$
(0.73)
$
(0.89)
$
(1.11)
$
(1.42)
$
$ 2.06 $ 2.04 $ 1.98 $ 1.91 $ 1.85 $
1.87 $
1.90 $ (0.68)
1.92 $ (0.63)
1.91 $ (0.50)
$ 1.85
0.23 $ (0.24)
(1.71)
$
(1.83)
$
(1.92)
$
(1.98)
$
$ (1.97)
3.89
2.97
2.42
2.10
1.91 $
$ 0.46 $ 0.22 $ 0.12 $ 0.10 $ 0.14 $
$ (1.62) $ (1.35) $ (1.14) $ (0.98) $ (0.84) $
$ (2.26)
0.48 $ (1.90)
0.63 $ (1.62)
0.73 $ (1.39)
0.79 $ (1.20)
0.84 $
$ (5.45)
0.46 $
0.36 $ (3.01)
0.23 $ (3.49)
0.07 $ (4.04)
(0.16) $ (4.69)
0.05 $ (4.89)
0.07 $ (4.15)
0.13 $ (3.53)
0.22 $ (3.00)
0.31 $
$ (5.77)
1.06 $ (0.10)
1.06 $ 1.01
0.39 $
0.24 $ 0.86
0.07 $ 0.94
$ (0.27)
5.15 $ (2.06)
4.83 $ (1.68)
4.54 $ (1.38)
4.28 $ (1.13)
4.04 $
$ (2.55)
$ (1.76)
1.81 $
1.79 $ (1.67)
1.76 $ (1.76)
1.68 $ (1.83)
1.53 $ (1.84)
1.89 $ (5.63)
1.38 $ (5.00)
1.10 $ (4.45)
0.96 $ (3.97)
0.89 $
$ (6.35)
$
(1.52) $
$ (2.05)
(1.80) $
$ (2.27)
(2.10) $
$ (2.52)
(2.40) $
$ (2.83)
(2.69) $
$ (3.21)
$
$ (1.11) $ (0.90) $ (0.74) $ (0.62) $ (0.52) $
$ (6.75) $ (5.86) $ (5.10) $ (4.44) $ (3.87) $
$ (1.25) $ (1.15) $ (1.02) $ (0.87) $ (0.72) $
$ (3.38) $ (2.87) $ (2.46) $ (2.13) $ (1.86) $
$ 0.70 $ 0.80 $ 0.85 $ 0.88 $ 0.89 $
$ (6.11) $ (5.63) $ (5.17) $ (4.74) $ (4.35) $
Expanding
$ (2.46) $ (2.45) $ (2.35) $ (2.20) $ (2.02) $
Yes
(0.73) $ (0.63)
No
0.87 $ 0.91
Yes
(2.61) $ (2.26)
No
0.40 $ 0.48
No
0.79 $ 0.72
No
3.83 $ 3.63
Yes
(1.57) $ (1.46)
PM Treatment
No
0.88 $ 0.88
5
6
Effective?
Yes
(1.86) $ (1.69)
(0.35)
(0.43) $ (1.73)
(1.84)
Yes
(2.96)
(3.38) $ (0.45)
(0.46)
Yes
Yes
(0.44)
$
(0.57)
(1.03) $ (0.98)
Yes
Yes
(1.42)
$
(1.62)
0.04 $ 0.05
No
No
0.89
$
0.89
(1.11) $ (1.00)
Yes
Yes
(3.66)
$
(3.99)
1.00 $ 0.97
No
Yes
(1.84) $ (1.66)
(0.36) $ (0.34)
Yes
Yes
(0.61)
$
(0.68)
0.82 $ 0.81
No
No
0.21
$
0.13
(0.87) $ (0.79)
Yes
Yes
(1.18)
$
(1.35)
0.77 $ 0.76
No
No
1.26
$ (0.44)
1.27 $
(0.50)
Yes
Yes
(0.42)
$
(0.50)
1.78 $ 1.72
No
No
1.81
1.84 $ (0.68)
(0.70)
Yes
Yes
(1.48)
$
(1.59)
1.80
1.74
No
No
0.20 $ 0.27
(0.73) $ (0.63)
Yes
Yes
(1.04)
0.87 $ (0.90)
0.91
No
(2.61)
Yes
No
0.61
0.54 $ (2.26)
0.40 $ (2.18)
0.48
No
Yes
(2.55)
0.79
No
0.63
0.52 $ 0.72
3.83 $ (0.76)
3.63
No
Yes
(0.93)
(1.57)
Yes
No
1.82
1.82 $ (1.46)
0.88 $ (3.17)
0.88
No
Yes
(3.55)
Yes
(1.02)
$ (1.69)
(1.26)
(1.86) $
Yes
(0.43) $ (0.35)
Yes
(3.38) $ (2.96)
Yes
(0.57) $ (0.44)
Yes
(1.62) $ (1.42)
Yes
0.89 $ 0.89
No
(3.99) $ (3.66)
Yes
the Realm of Possibility
(1.84) $ (1.66)
Yes
Probabilistic Methodology
Pre-defined statistical distributions for selected
input parameters, based on historical data or
assumptions
Hundreds of simulated total LCCs, based on
randomly selected values of input parameters
Resulting frequency/cumulative distributions of
life-cycle costs for alternative design strategies
Interpretation of results based on probabilities
46
Expanding the Realm of Possibility
Probabilistic Approach
Identify the structure and logic of the problem
Quantify the uncertainty using probability
Perform simulation
Analyze and interpret results
Make a decision based on assessment of risk
47
Expanding the Realm of Possibility
Structure and Logic
Identify design alternatives
Develop life cycle maintenance plan
Confirm cash flow
Define variability (both certain and uncertain)
Costs
Treatment life
Discount rates, etc.
48
Expanding the Realm of Possibility
Inputs
Initial
Pavement
life span
Discount
Rate
Future
M&R
Life spans
1. Values randomly
selected from each input
sampling distribution
2. Life-cycle cost
computation is
performed
3. Process repeated many
times
Output
Projected
Life-Cycle Costs
Initial
Cost
Future
Costs
Expanding the Realm of Possibility
Probabilistic Approach
Deterministic LCCA treats all input values as
discrete
However, most inputs have an element of
uncertainty
Deterministic methods treat all inputs as means
or best guesses
50
Expanding the Realm of Possibility
Probabilistic Approach
Probabilistic methods allow for the introduction
of risk
What can happen?
How likely is it to happen?
What are the consequences?
51
Expanding the Realm of Possibility
How do we account for uncertainty?
Identify the input variability
Calculate what if scenarios
ie, mean and standard deviation
Monte Carlo simulation
Decisions can be made based on the
probability of occurrence
52
Expanding the Realm of Possibility
Uncertainty and Probability
Need to develop probability distributions
Numerous distributions to evaluate probability
Can be developed based on statistical analysis
and goodness of fit of existing data
Can be developed based on expert opinion
53
Expanding the Realm of Possibility
Probability Distribution Types
54
Expanding the Realm of Possibility
Probability Distribution
Most commonly used in transportation life-cycle
costing applications
Normal
mean
Triangular
most likely
Probability
std dev
55
Expanding the Realm of Possibility
Incorporating the Distribution
Can use existing spreadsheets
Addition of commercially available software, ie
@RISK
Crystal Ball
FHWA RealCost
Software programs add probability distribution
functions and simulation techniques
56
Expanding the Realm of Possibility
Simulation
Rigorous sensitivity analysis based on
probability distribution variables
Iterates separate solutions based on random
number sampling
Each iteration represents a possible solution
Iterative results are compiled and statistically
analyzed
57
Expanding the Realm of Possibility
Simulation Example
Forecast: Conv entional
1,000 Trials
Frequency Chart
14 Outliers
.027
27
.020
20.25
.014
13.5
.007
6.75
.000
0
$103,165
$123,538
$143,911
$164,284
$184,657
Certainty is 27.10% from -Infinity to $131,297 $
27.1 percent probability that conventional alternative will have
lower cost than $131,297 – (value from deterministic)
Expanding the Realm of Possibility
Simulation Example
Forecast: Prev entiv e Maintenance
1,000 Trials
Frequency Chart
12 Outliers
.028
28
.021
21
.014
14
.007
7
.000
0
$102,433
$118,533
$134,632
$150,732
$166,831
Certainty is 49.50% from -Infinity to $131,297 $
49.5 percent probability that preventive alternative will have
lower cost than $131,297 – (value from deterministic)
Expanding the Realm of Possibility
Alternative Comparison
Overlay Chart
Frequency Comparison
.073
Conv entional
.055
.037
.018
Preventive Maintenanc e
.000
$100,000
$122,500
$145,000
$167,500
$190,000
Preventative maintenance alternative always less expensive
than conventional for modeling conditions
Expanding the Realm of Possibility
Alternative Comparison
Overlay Chart
Preventive versus Conventional Treatm ent
1.000
Preventive
.750
.500
Conventional
.250
.000
$90,000
$115,000
$140,000
$165,000
$190,000
Probability that preventive maintenance alternative always less
expensive than conventional for modeling conditions
Expanding the Realm of Possibility
Interpretation of Results
Unlike deterministic method, lowest cost is not
the only factor
Need to look at the likelihood of a particular
outcome occurring
Histograms and cumulative risk profiles are
convenient tools
62
Expanding the Realm of Possibility
Probabilistic Including User Costs
Activity
Initial Rehabilitation
Micro-Surfacing
Thin Overlay Plus Repairs
Reconstruction Cost
Mean
Std Dev
Trial
$418,407.00 $27,000.00
$590,000.00
$22,500.00
$2,800.00
$310,000.00
$194,244.00 $45,000.00
$310,000.00
$750,000.00 $221,100.00 $1,120,000.00
Work Zone Cost Data
Initial Work Zone Cost
Second Work Zone Cost
Third Work Zone Cost
Reconstruction Work Zone Cost
$130,000.00
$15,000.00
$57,000.00
$265,000.00
Service Life Data
Life of Initial Rehabilitation
Life of Second Rehabilitation
Life of Third Rehabilitation
Life of Reconstruction
Timing of Second Rehabilitation
Time of Third Rehabilitation
Time of Reconstruction
Time of Final Rehabilitation
Discount Rate
18
10
15
23
0.05
$16,500.00
$1,500.00
$7,000.00
$47,700.00
2.9
2.3
1.8
4.8
0.01
$130,000.00
$90,000.00
$115,000.00
$265,000.00
13
9
8
20
13
22
30
50
0.07
Activity
Present Worth
Initial Rehabilitation
$590,000.00
Second Rehabilitation
$128,638.98
Third Rehabilitation
$69,971.08
Reconstruction Cost
$147,131.17
Salvage
-$110,348.38
Total Construction
$825,392.85
$130,000.00
$37,346.80
$25,957.01
$34,812.29
Total Work Zone Cost
$228,116.10
Total Overall Costs
$1,053,508.95
EUAC
$63,748.36
$17,618.31
$81,366.67
Overlay Chart
Total Agency and User Costs
.149
.112
.075
.037
.000
$100,000.00
$225,000.00
$350,000.00
$475,000.00
$600,000.00
Expanding the Realm of Possibility
Expanding the Realm of Possibility
Expanding the Realm of Possibility
Additional References
Expanding the Realm of Possibility
Overall Goals and Benefits
Higher user satisfaction
Better informed decisions
Improved treatment
performance
Increased safety
Cost saving
Improved pavement
condition
Expanding the Realm of Possibility
Questions?
Expanding the Realm of Possibility