This document discusses pavement thickness design according to the New York State Department of Transportation guidelines. It provides an overview of flexible and rigid pavement design, including the factors considered such as traffic loading, material properties, and design methods. The key design methods covered are the ESAL-based method for projects over 1.5km in length, and the conventional method using thickness tables for shorter projects. An example calculation is provided to illustrate the ESAL method for determining equivalent single axle loads and selecting pavement thicknesses.

1. PAVEMENT THICKNESS
DESIGN
CTC 440

2. OBJECTIVES
 Know how to determine the thickness of
flexible/rigid pavements

3. COMPREHENSIVE PAVEMENT
DESIGN MANUAL (PDM)
 NYS PDM can be found at
https://www.dot.ny.gov/divisions/engineeri
ng/design/dqab/cpdm
 Chapter 4 (New
Construction/Reconstruction) is what we’ll
cover
https://www.dot.ny.gov/divisions/engineeri
ng/design/dqab/cpdm/repository/chapter4.
pdf

4. CPDM-OTHER AREAS
 Ch 2 Evaluation of Existing Pavements
 Ch 3 Project Development Process
 Ch 5 Rehabilitation
 Ch 6 Materials
 Ch 7 Shoulders
 Ch 8 Pavement Joints
 Ch 9 Subsurface Pavement Drainage
 Ch 10 Preventative Maintenance

5. INTRODUCTION:
 NYSDOT uses a modified version of the AASHTO’s
1993 Guide for the Design of Pavement Structure
 Features include
 Thickness design procedure for pavements
 50-year design life
 Permeable base layer for drainage
 Edge drains or daylight
 Full-depth shoulders

6. RIGID PAVT. (PCC)
Used for
 High volume traffic lanes
 Freeway-to-freeway connections
 Exit ramps
Advantages
 Durability
 Long service life
 Withstands repeated flooding and subsurface water w/o deterioration
DisAdvantages
 May lose original nonskid surface
 Must have even subgrade/uniform settling
 Joints
Reinforced
 Contraction joints (50-100ft)
 Epoxy-coated steel to prevent corrosion
Unreinforced
 Contraction joints (15-30x pavt thickness)

8. FLEXIBLE PAVT. (HMA)
Used for
 Traffic and auxiliary lanes
 Ramps, parking areas, frontage roads and shoulders
Advantages
 Adjusts to limited amounts of differential settlement
 Easily repaired and overlaid
 Non-skid properties do not deteriorate
Disadvantages
 Loses flexibility/cohesion over time
 Must be resurface sooner than concrete
 Not usually chosen where water is expected
Minimum layer is usually 1-1/2”
 1-1/2” top course
 1-1/2” binder course
 Remaining thickness is base course

10. MATERIAL DESIGN-ASPHALT
 Superpave http://www.youtube.com/watch?v=GPwWNKYrQw8
 Marshal Mix (old)

11. PERPETUAL PAVEMENT
 Introduced in 2003 by the National Center for
Asphalt Technology and the Asphalt Pavement
Alliance
 HMA pavement designed to last 50 years or more
without major structural rehabilitation or
reconstruction
Ref: http://asphaltroads.org/images/documents/ghg-carbon_footprint_of_various_pavement_types.pdf

12. CARBON FOOTPRINT OF HMA AND PCC
PAVEMENTS
http://asphaltroads.org/images/documents/carbon_footprint_web.pdf

13. WHY THE DIFFERENCE
 Carbon is sequestered in the HMA pavement
 CO2 is released when producing portland cement
via kiln; limestone disassociation produces CO2
Ref: http://asphaltroads.org/images/documents/ghg-carbon_footprint_of_various_pavement_types.pdf

14. OTHER “GREENER” PAVEMENTS
 Warm-Mix Asphalt (WMA)
 86.7 million tons in 2012
 Reclaimed Asphalt Pavement (RAP)
 68.3 million tons in 2012
 Reclaimed Asphalt Shingles (RAS)
Other:
Ground tire rubber, steel and blast furnace slag,
other waste materials (repurposed into
pavement)
Reference Report: http://www.asphaltpavement.org/index.php?
option=com_content&view=article&id=872&Itemid=61

15. BASIS FOR THICKNESS DESIGN
 Axle loading from truck traffic
 An 80kN axle load (18-kip axle load in
English units) is standard loading. All
traffic is converted into the number of 80-
kN passes that would cause the same
structural damage
 The converted # is referred to as the 80kN
ESAL (Equivalent Single Axle Loads)
 The effect of passenger cars, pickups, 2-
axle trucks w/ single rear tires and buses
(FHWA vehicle classes 1-4) are not even
considered

16. RIGID PAVEMENTS-ESAL
 Modified AASHTO equation is used
 Modified because NYSDOT experience is that
pavements in NYS last longer than would be
predicted from the original equation
 Other method
 Fatigue Strength

18. FLEXIBLE PAVEMENT-ESAL
 AASHTO equation is used
 Other methods
 CALTRANS
 Asphalt Institute

20. DETERMINING ESAL-SIMPLE
METHOD (WORKSHEET ON 4-9)
 Design life
 Initial 2-way AADT
 % HV (class 4 or greater)
 % of all trucks in the design direction
 % of all trucks in the design lane
 Truck equivalency factor
 Annual truck volume growth rate
 Annual truck weight growth rate

22. ESAL METHOD-STEPS
 Determine ESAL
 Determine HMA thickness by using table
4-5
Mr-subgrade resilient modulus (load carrying
capabilities of the materials below the pavt.)
Mr=28 (clay); Mr=62 (gravel)
 Determine PCC thickness by using Table
4-4

23. ESAL-EXAMPLE-BOTH PCC AND HMA
(ASSUME MR=48 MPA)
AADT % HV DHV DDHV
2006 3165 6 325 195
2011-ETC 3494 6 359 215
2021 4260 6 437 262
2031 5192 6 533 329
2041 6330 6 650 390

24. EXAMPLE: STEPS
 Determine whether the traffic growth rate is
simple or compound
 Determine the growth rate and % traffic in the
design direction
 Determine the ESAL
 Determine the pavement thickness

25. EXAMPLE-ANSWERS
 Determine whether the traffic growth rate
is simple or compound (compound)
 Determine the growth rate (2%) and %
traffic in design direction (60%)
 Determine the ESAL (see next slide)
HMA – 6.42E6
PCC – 8.80E6
 Determine pavt. thickness
HMA 165 mm (7”)
PCC 225 mm (9”)

27. ESAL-BASED METHOD
 Projects over 1.5 km in length

28. CONVENTIONAL METHOD
 Projects < 1.5 km in length
 Use Table 4-1
 For Interstate Highway Conventional Pavement
Requirements see page 4-2
 For our previous example:
 HMA 160mm (6.5”)
 PCC not applicable