Perpetual Pavements in Delivering Smooth road
description
Transcript of Perpetual Pavements in Delivering Smooth road
David E. Newcomb, P.E., Ph.D.Texas A&M Transportation Institute
Texas A&M University
The Role of Perpetual Pavementsin Delivering
Smooth, Safe and Well-‐Maintained Roads
Australia & Texas:A Case for A Partnership!
Pavement Engineer Genome Project
People
• Texas: 25,674,681 (2011)• Australia: 22,328,800 (2011)
• Texas has cowboys.• Australia has stockman.• Both love country music.
Wide Open Spaces
Animals that Hop
Only Texas has the Jackalope
Marsupials
Pavement Basics• Layers are necessary to provide economy while protecting ‘weak’ materials
Pavement Design: Where were we?
• Using 1960s performance equations• 1950s type of load• Thin pavement structures (Max. 6” HMA)• Meaning of structural coefficients• Limited reliability analysis• Some movement to M-‐E
AASHO Road Test Trucks
( )
( )
07.8log32.2
110944.0
5.12.4log
20.01log36.9log19.5
018 −+
++
⎥⎦
⎤⎢⎣
⎡−
Δ
+−++= RR M
SN
PSI
SNSZW
AASHTO Design Equation
Perpetual Pavement Design Features
Max Tensile Strain
PavementFoundation
Rut Resistant Intermediate Course75 – 100 mm (3 – 4”)
Durable Base100 – 250 mm (4 – 10”)
38 – 75 mm (1.5 -‐ 3”) SMA, OGFC or Superpave} ZoneofHigh
Compression
Perpetual Pavement versusConventional Design
0
5
10
15
20
25
0.1 1 10 100 1000
HMA Thickness, in.
Traffic, ESAL
AASHTO
PerRoad
Perpetual Pavements• Resist Structural Distresses– Fatigue Cracking– Rutting
• Withstand Climate and Traffic– Design for Subgrade Modulus– Use Strong Foundation– Mix Design– Materials Selection
Perpetual Pavement Advantage• Efficient Design – No Overdesign• Avoid Reconstruction• Reduce Rehabilitation• Reduce Life Cycle Cost• Reduce Energy Consumption• Reduce Materials Use
DBM
DBM50HDM
Design life (msa)
Thickness of asphalt layers(mm)
500
400
300
200
100
0
DESIGN CURVES FORASPHALT PAVEMENTS
Thickness of bituminous layer (mm)
Rate ofrutting
(mm/msa)
0 100 200 300 4000.1
1
10
100
1000
RATE OF RUTTING vsBOUND LAYER THICKNESS
New Jersey I-‐287Surface Cracking
Design Applications• High Volume Pavements– MEPDG– PerRoad– TTI
• Low and Medium Volume Pavements– PerRoad
• High Modulus Bases• Pavement Rehab – SHRP 2 – Project R23– Using Existing Pavement in Place and Achieving Long Life– Rubblization– Overlays
Performance
• Perpetual Pavement Awards• European Studies• Oregon and Washington Studies• New Jersey• Connecticut• Kansas– Review of interstate performance– Test sections
Asphalt vs. PCC Life
0
200
400
600
800
1000
0 - 10 11 - 20 21 - 30 31 - 40 41 - 50 51 - 60 61 or More
Age (Years)
Lane Miles
HMA (Lane Miles)PCCP (Lane Miles)WSDOT
Interstate Ages
Smoothness
0
200
400
600
800
1000
1200
0.0 - 0.5 0.5 - 1.0 1.0 - 1.5 1.5 - 2.0 2.0 - 2.5 2.5 - 3.0 3.0 - 3.5 3.5 - 4.0 4.0 - 4.5 4.5 - 5.0 5.0 orMore
IRI (m/km)
Lane Miles
HMA (Lane Miles)PCCP (Lane Miles)
WSDOT Interstate – Roughness (2004)
RUBBLIZATION WITH PERPETUAL PAVEMENT OVERLAY
VERSUS REMOVE/REPLACE PCC
First Cost Comparisons
• One Lane-‐Mile (7040 SY)• Case 1: Rubblization with Perpetual Pavement• Case 2: Remove PCC and Replace with PCC
Case 1
• Perpetual Pavement with Rubblization– Rubblize28 cm PCC– Overlay with 20 cm HMA
• Initial Cost:• 2013 Bid Tabs
– CO Rubbl. ~ $5.00– CO SMA ~ $85.00– CO HMA ~ $75.00– TX HMA ~ $70.00– WA HMA ~ $85.00
Item Unit Cost
Edge Drains
5.00/ft16.40/m
Rubblize 5.50/yd2
6.57/m2
HMA Overlay
80.00/ton88.00/t
Case 2
• Remove/Replace PCC – Remove PCC– Replace with 11” PCC
• Initial Cost:– 2013 Bid Tabs PCC
• CO ~ $34.00• WA ~ $47.00
Item Unit Cost
Remove PCC 25.00/yd2
29.90/m2
PCC Placement
41.00/yd2
49.04/m2
Initial Cost Comparison
0
100000
200000
300000
400000
500000
Rubblize and Overlay
Remove/Replace PCC
Cost, $/lan
e-‐mile
Δ = 32%
General Experience
• First Cost: Rubblization ~ 32% less than remove/replace
• Speed of Construction: days vs. weeks• Impact of User Costs?
Work Zone Assumptions
• 1 mile long• 4 lanes • One lane open each direction during work• 40,000 ADT
Case 1• Rubblization: One lane-‐mile/day production• Paving: 2 lane-‐miles/day– Sequence
• 3” bottom lift• 3” 2nd lift• 2” 3rd lift
– 24 hour closure until 2nd asphalt lift– 12 hour closure for 3rd
Case 2• Remove/Replace PCC– Removal: 2000 SY/day ~ 2 days/lane – 24 hr/day– Trim Base and Set Dowels – 12 hr– Paving: 0.75 mile/day – 11 hr– Curing: 3 days – 24 hr/day
User Costs
0
10000
20000
30000
40000
50000
60000
70000
Rubblize and Overlay Remove/Replace PCC
Cost, $/lan
e-‐mile
Δ = 58%
Life Cycle Costs• Asphalt– Initial Construction– Overlay Every 15 years
• Concrete– Initial Construction– Grind at Year 15– Overlay at 25 years– Overlay at 35 years
Life Cycle Costs
0
100000
200000
300000
400000
500000
600000
700000
Rubblize and Overlay Remove/Replace PCC
Cost, $/lan
e-‐mile
Δ = 22%
Summary• Perpetual Pavement design is improving– More efficient pavements– More cost-‐effective
• Construction issues need to be addressed• Perpetual Pavement is Less Expensive– Initial Cost– User Cost – Life Cycle Cost
Tools for Performing Perpetual Pavement Design and LCCA
• LCCA Software – Asphalt Pavement Alliance– Follows FHWA Guidance– LCCA Software – Full probabilistic analysis– LCCA Express – Direct comparison of two options –deterministic.
• Design Software– PerRoad – Full Perpetual Pavement Design– PerRoadXpress – Better for lower volume roads, streets and parking lots
• www.AsphaltRoads.org