1. PaveDAT Pavement Damage Assessment Tool Roger Mingo, P.E.
R.D. Mingo and Associates

2. Origin FHWA Need: Easy-to-Use Pavement Damage Assessment Tool
Needed Alternative to ESALs
Joint Research Project of FHWA’s Offices of Policy and Freight Management and Operations
PaveDAT: Simplified Version of NAPCOM (National Pavement Cost Model)

3. Approach Used ME-PDG (Mechanistic-Empirical Pavement Design Guide)
ARA Designed MEPDG, Auburn University Helped with Application
Applied Model Thousands of Times to Derive New Pavement Damage Equivalence Factors

4. Load Equivalence Factors (LEFs)
ESALs (Equivalent Single Axle Loads)– One Type of LEF
ESALs Based on 50-Year-Old Study in Single Location
ESALs Widely Seen as Outdated and Based on Many Assumptions
New LEFs Developed for PaveDAT and NAPCOM Independent of ESALs

5. Overview of PaveDAT
Model estimates pavement costs for specific vehicles and types of trips
Model can use national average data, state default data, or user-supplied data
After state customization, as needed, model is simple to use
User supplies vehicle axle weights and trip information

6. User Inputs
Axle weight for each axle group (tandems and tridems are each considered one axle group)
Number of axles in each group
Miles of travel on Interstate, State, and Local roads

7. Results Cents per mile of travel Total costs in dollars
Costs shown by highway system as well as for total trip

8. Special Permit Pavement Cost Estimator
Using Pavement Data for:
Natl. Avg.
Miles of Travel by Type of Highway
Interstate Highway 85
State Highway 12
County / Local Road 3
Total
100
Axle Descriptions
Weight (kips)
# Axles
Steering Axle 1
Drive Axle 34 2
Axle Group 3 51
Axle Group 4
Axle Group 8 97 6
Results: Estimated Pavement Costs
Miles
$ / Mile
Pavement Cost
$0.4197
$35.67
$0.7614
$9.14
$1.5729
$4.72
$0.4953
$49.53

9. 97,000- Lb Six-Axle Truck (3S3) Results
Results: Estimated Pavement Costs
Miles
$ / Mile
Pavement Cost
Interstate Highway 85
$0.4197
$35.67
State Highway 12
$0.7614
$9.14
County / Local Road 3
$1.5729
$4.72
Total
100
$0.4953
$49.53

10. 80,000-Lb Five-Axle Truck (3S2) User Inputs
Miles of Travel by Type of Highway
Interstate Highway 85
State Highway 12
County / Local Road 3
Total
100
Axle Descriptions
Weight (kips)
# Axles
Steering Axle 1
Drive Axle 34 2
Axle Group 3
Axle Group 4
Axle Group 8 80 5

11. 80,000-Lb Five-Axle Truck (3S2) Results
Results: Estimated Pavement Costs
Miles
$ / Mile
Pavement Cost
Interstate Highway 85
$0.3498
$29.73
State Highway 12
$0.5703
$6.84
County / Local Road 3
$1.1017
$3.31
Total
100
$0.3988
$39.88
Now let’s look at another example. Here is the same vehicle on the same highways, but operating at 80,000 pounds instead of 71,000 pounds. We put the data in the same way, and bling– the pavement cost estimate goes up from 24.5 cents per mile to 39.3 cents per mile.
The weight went up 13 percent and the pavement costs went up 60 percent. Are you surprised? Probably not, if you have worked for long around trucks and highways. You might have heard about “the fourth power law”, or you might just have seen how much more pavements deflect with the heaviest vehicles.

12. 71,000-Lb Five-Axle Truck (3S2) User Inputs
Miles of Travel by Type of Highway
Interstate Highway 85
State Highway 12
County / Local Road 3
Total
100
Axle Descriptions
Weight (kips)
# Axles
Steering Axle 11 1
Drive Axle 30 2
Axle Group 3
Axle Group 4
Axle Group 8 71 5
Now let’s look at another example. Here is the same vehicle on the same highways, but operating at 80,000 pounds instead of 71,000 pounds. We put the data in the same way, and bling– the pavement cost estimate goes up from 24.5 cents per mile to 39.3 cents per mile.
The weight went up 13 percent and the pavement costs went up 60 percent. Are you surprised? Probably not, if you have worked for long around trucks and highways. You might have heard about “the fourth power law”, or you might just have seen how much more pavements deflect with the heaviest vehicles.

13. 71,000-Lb Five-Axle Truck (3S2) Results
Results: Estimated Pavement Costs
Miles
$ / Mile
Pavement Cost
Interstate Highway 85
$0.2153
$18.30
State Highway 12
$0.3668
$4.40
County / Local Road 3
$0.7294
$2.19
Total
100
$0.2489
$24.89

14. Pavement Cost Comparison Example
Vehicle
Cost per Mile
97,000-Pound 6-Axle
49.53
80,000-Pound 5-Axle
39.88
71,000-Pound 5-Axle
24.89
Now is a good time to consider another important question. Suppose we are issuing a permit for this 97,000 pound vehicle. How much shall we charge it for the permit? (Or at least for the pavement costs associated with the pavement– you are on your own for how much you charge for everything other than pavement costs).
We could charge it for all pavement costs, 49 cents per mile.

15. Pavement Cost Comparison Example
Vehicle
Cost per Mile
97,000-Pound 6-Axle
49.53
80,000-Pound 5-Axle
39.88
Difference
9.65
Or we could charge it for the difference between its costs and the costs of the heaviest legal truck (let’s assume for this example that is an 80,000-pound 5-axle vehicle), or about 10 cents per mile.

16. Pavement Cost Comparison Example
Vehicle
Cost per Mile
97,000-Pound 6-Axle
49.53
71,000-Pound 5-Axle
24.89
Difference
24.64

17. Pavement Cost Comparison Example
Vehicle
Cost per Mile
97,000-Pound 6-Axle
49.53
User Fees Paid per Mile
9.27
Difference
40.26

18. Specifying A Base Vehicle
Base Vehicle Axle Descriptions
Weight (kips)
# Axles
Steering Axle 11 1
Drive Axle 30 2
Axle Group 3
Axle Group 4
Axle Group 5
Axle Group 6
Axle Group 7
Axle Group 8
Total 71 5

19. 97,000- Lb 3S3 Compared to 71,000 Base
Results: Estimated Pavement Costs
Miles
$ / Mile
Pavement Cost
Interstate Highway 85
$0.2044
$17.37
State Highway 12
$0.3946
$4.73
County / Local Road 3
$0.8435
$2.53
Total
100
$0.2464
$24.64

20. 88,000- Lb 3S2 Compared to 71,000 Base
Results: Estimated Pavement Costs
Miles
$ / Mile
Pavement Cost
Interstate Highway 85
$0.3494
$29.70
State Highway 12
$0.5017
$6.02
County / Local Road 3
$0.8759
$2.63
Total
100
$0.3835
$38.35

21. 80,000- Lb 3S2 Compared to 71,000 Base
Results: Estimated Pavement Costs
Miles
$ / Mile
Pavement Cost
Interstate Highway 85
$0.1344
$11.43
State Highway 12
$0.2035
$2.44
County / Local Road 3
$0.3723
$1.12
Total
100
$0.1499
$14.99

22. Overview of Underlying Elements
Load Equivalence Factors (LEFs) based on thousands of runs of latest pavement models
Weight data for vehicle fleet comes from millions of WIM observations
Costs per mile based on national current pavement expenditures per truck mile
Load-related share of pavement costs based on recent state cost-allocation studies

23. Load Equivalence Factor Example
Distress Levels at 18,000 and 20,000 Trucks per Day
ADTT
Long Crk
Allig Crk
AC Rut
Total Rut
IRI
18,000
750
7.8
0.502
0.924
142.40
20,000
869
8.7
0.527
0.955
144.00
Distress Levels with 18,000 ADTT and Added 34-Kip Tandem Axles
Axles
Long Crk
Allig Crk
AC Rut
Total Rut
IRI
500
803
8.1
0.510
0.933
142.90
900
846
8.3
0.517
0.940
143.20
1100
869
8.4
0.520
0.943
143.40
1500
913
8.6
0.527
0.950
143.80
3000
1080
9.3
0.551
0.974
145.10

24. Estimating Target Number of Axles

25. Load Equivalence Factor Example (Continued)
Daily Axles to Reach Target Distress Levels
Weight
Type
Long Crk
Allig Crk
AC Rut
Total Rut
IRI 8
Single 18
1453.0
2651.9
3170.4
2320.0 28
245.7
1017.6
972.7
527.3 16
Tandem
7692.3
9333.3 34
1100.0
1767.1
1500.0
1812.5
1730.8 48
272.3
435.6
770.0
676.9
566.7 60
110.9
177.0
443.8
161.4 24
Tridem
4487.5
5422.7
6536.4
8294.7 51
200.0
1591.9
1018.2
1177.8 72
49.2
395.5
500.0
130.0
153.8

26. Overview of Underlying Elements
Load Equivalence Factors (LEFs) based on thousands of runs of latest pavement models
Weight data for vehicle fleet comes from millions of WIM observations
Costs per mile based on national current pavement expenditures per truck mile
Load-related share of pavement costs based on recent state cost-allocation studies

27. Overview of Underlying Elements
Load Equivalence Factors (LEFs) based on thousands of runs of latest pavement models
Weight data for vehicle fleet comes from millions of WIM observations
Costs per mile based on national current pavement expenditures per truck mile
Load-related share of pavement costs based on recent state cost-allocation studies

28. Options to Customize
States can use their pavement knowledge to modify pavement distress distributions
States can enter their own detailed pavement cost information
States can update WIM data
States can combine and weight the default data from adjacent states

29. Current Status PaveDAT Was Completed in 2011
Presentations Made to 5 Pilot States
Application So Far Has Been for Special Studies
Applied in Some Form in Oregon, DC, and Wisconsin
Texas is Adapting Model for Its Use