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Importance of Pavement design & District supportRoberto Treviño Flores, P.E.MNT – Pavement Analysis & Design
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Pavement Design in Texas6”
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AMARILLO EL PASO PHARR ODESSA PARIS HOUSTON DALLAS SAN ANTONIO
Pavement design for a traffic projection of 10 million ESALs
Pavement Base StabilizedSubgrade
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Table of contents
6-8
9-16
17-26
27
28-33
4-5Pavement design process
Importance of understanding your traffic projection
Importance of considering design and construction aspects
Importance of pavement investigation (forensics)
Summary and conclusion
District Support – How do we help?
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3
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Pavement Design Process
4
Evaluate
drainage
Evaluate
Subgrade
properties
Perform NDT (GPR and
FWD)
Collect soil samples
Evaluate origin of distress
Project selectionObtain TPP
Traffic projection Conduct site investigation
Select pavement rehab strategy
A good pavement design is one that is:– Cost effective– Can be built– Meets design requirements
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Pavement Design Process
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Critical considerations for a successful pavement design1. Understand your traffic projection2. Consider design and construction aspects 3. Pavement investigation
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Importance of understanding your traffic projection
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What is 1 ESAL?– The DAMAGE of an 18,000 lb. single axle to a pavement
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Importance of understanding your traffic projection
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Axle Load(lbs) Axle type LEF (flexible)
SN = 3
12,000 Single 0.23
18,000 Single 1.0
30,000 Single 7.9
18,000 Tandem 0.11
34,000 Tandem 1.11
LEF Example: 80,000 lb truck Steering axle @ 12,000 lb = 0.23 ESAL Drive axle @ 34,000 lb = 1.11 ESAL Trailer axle @ 34,000 lb = 1.11 ESAL
Truck factor = 2.45 ESAL
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Importance of understanding your traffic projection
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What does this mean? Your proposed roadway will receive the 20 yr. traffic projection in ~5-6 years
Assume a truck factor = 1.0 ESAL/truck
(250 trucks/day)(1.0 ESAL/truck)(365 days/year)(20 years) = 1,825,000 ESAL
ESAL projection
Assume a truck factor = 1.0 ESAL/truck
(500 trucks/day)(1.0 ESAL/truck)(365 days/year)(20 years) = 3,650,000 ESAL
ESAL projection + truck % doubles
Assume a truck factor = 1.7 ESAL/truck
(500 trucks/day)(1.7 ESAL/truck)(365 days/year)(20 years) = 6,205,000 ESAL
ESAL projection + truck % doubles + Energy sector traffic
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Importance of considering design and construction
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Prior to pavement evaluation we need to understand the project scope
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Importance of considering design and construction
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How much pavement width do we have?
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Importance of considering design and construction
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What are we trying to build?
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Importance of considering design and construction
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How do we get there?
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Importance of considering design and construction
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Assumptions:– There are no available detours– The existing roadbed needs to carry traffic– Project needs to be built half at a time– Half of the road is only 20 feet wide
Requirements:1. Pavement needs a temporary widening to handle 2 way traffic2. A buffer is required for construction activities and safety3. The shoulder needs structural evaluation
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Importance of considering design and construction
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Widening considerations
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Importance of considering design and construction
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Widening considerations
– Shoulder evaluation
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Importance of considering design and construction
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Widening considerations– Temporary pavement and widening joint location
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Importance of considering design and construction
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Widening considerations– Drainage
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Importance of considering design and construction
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Widening considerations
– Match existing as best as possible
– Bound base widening can trap moisture
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Importance of considering design and construction
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Failures can occur in widening section
Joint in WP Drainage problem
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Importance of pavement investigation
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Begin your investigation once all design factors are considered
• Step 1: Investigate historical data
• Step 2: Perform NDT (GPR & FWD)
• Step 3: Develop your sampling and testing plan
• Step 4: Select your rehab strategy
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Importance of pavement investigation
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Step 1: Investigate historical data– Structure that was originally designed– Maintenance history– Field changes during construction
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Importance of pavement investigation
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Step 2: Perform NDT (GPR)
– GPR analysis for pavement thicknesses and irregularities
– Pavement irregularities need to be verified
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Importance of pavement investigation
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How to verify the irregularities?
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Importance of pavement investigation
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Importance of pavement investigation
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Remove/Replace
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Importance of pavement investigation
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Step 2: Perform NDT (FWD)
– Evaluate pavement stiffness and remaining life
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Importance of pavement investigation
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Sample # 3
Sample # 2
Sample # 1
Step 3: Develop your sampling and testing plan
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Importance of pavement investigation
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Is the material base or subgrade?
Lime Cement Fly Ash Asphalt Stabilizer blend
What are my options?
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Importance of pavement investigation
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Step 4: Select your rehab strategy
– Can we reuse the existing material?
– How much material can we salvage?
– Can we raise the profile?
You are now ready to run the pavement design programs
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Summary and conclusion
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Why is pavement design important? Proper pavement design ensures that the design is used to calculate
project cost rather than cost dictating the pavement design Selecting the proper design strategy at the right time for the right
application will produce the best value
Review your traffic data – your proposed roadway may receive the original projection sooner which will lead to premature failures
Envision how the project will be designed and constructed to avoid failures when the pavement design inputs are correct
Use NDT to select the proper fix – inadequate design may be a temporary solution and overdesign is not cost effective
Traffic Design and Construction Forensics
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District support – How do we help?
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How do we (MNT) help?– Pavement Design training– Pavement Design and SOP support– Pavement evaluations– Forensic investigations
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District support – How do we help?
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Pavement Design training – Flexible and Rigid– We visit the Districts and provide pavement design training
• Childress and El Paso are next
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District support – How do we help?
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Pavement Design and SOP support: [email protected]– We perform reviews and offer suggestions
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District support – How do we help?
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Pavement evaluations: #[email protected]– We provide pavement design support and offer recommendations– Pavement design contracts
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District support – How do we help?
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Forensic investigations: #[email protected]– We collaborate with MTD and Universities to support the Districts
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District support – How do we help?
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Portable WIM is available for Problematic Sites (Energy sector)
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Questions??
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Roberto Treviño Flores, P.E.Branch Manager, Pavement Analysis & [email protected]
Acknowledgments:Corey Barrow – AMAAldo Madrid – ELP
Sergio Cantu – PHRFrew Bogale – ODA
Wade Blackmon – PARSoojun Ha – HOUBoon Thian – DAL
Andres Gonzalez – SATGisel Carrasco - AUS
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