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Paving in the High Desert
Edwards Air Force Base, CA
Tri-Services Conference
April 23, 2008
Overview
• Project Scope
• DB Mentality
• The Team
• Design Precepts
• Construction Challenges
• Guiding Precepts
Edwards Project Layout
Main Runway
Temporary Runway Taxiway B Intersection
Taxiway A IntersectionTaxiway C Intersection
New Power Check Pads
Taxiway G Batch Plant
Pug Mill
Temp Water LineDry Lake Bed
New East Arm/ Dearm Apron
CH2M HILL/IHC JV Team
• Combines CH2M HILL innovation with IHC PCC paving expertise
• Represents:√ 60 years in federal work
experience√ Expertise in managing complex
construction operations√ Specializes airfield pavements on
high-security sites√ Nationally recognized aviation
design expertise…ASR, PCASE, technology
√ Recent Airfield pavement projects valued over $300 Million
√ Projects received the “Best PCC Pavement Constructed in the USA” in Military/Commercial Aviation categories
√ #1 program management√ #1 construction management-for-fee √ #8 design-build management√ Full service EPC integration worldwide
Integrated Design Build Team
• Sprit of Collaboration… Base on Trust
• Always Focus on the Problem… no blame!
• Meet Early and Often… High Communication
• Open Book… Tell Motivation and Disclose
• Level of Care… Code, Laws, Agency
• Always Align Expectation of Owner
Design can’t Make a Decision without Constructability Review
Builders Can’t Make a Decision without Design Standard Check
Open Book Mentality
• Focus on the Problem…not Your own team – Contingency Funds– Unstable Conditions– Schedule Changes– Stake Holder Info Flow
• “You Suck”– Weekly• QC Reconciliation Reviews
Edwards AFB Definition
Performance CostSchedule
No ASR
Meet Loading
Flight Operations
Environmental
Runway Sustainability
Taxiway Openings
Flight Transition to Temp
Performance Period
LD = $8000/day
Success
Program Amount
Funding Per FY
Manage to Cost
The Plan!!
Design Impact
• Innovations introduced early when influence on outcome was high
• Design had free access to Edwards and USACE
• Allowed quick exchange of ideas and approvals
• Internal team constructability meetings from Day 1
Edwards High Desert Conditions
• Mojave Desert, 100 miles NE of Los Angeles• Elevation of Base 2,300’• Average rainfall 6”/year, (Jan, Feb, Mar) = 4”• Summer average daily max 94 degrees• Summer high 110 degrees• Windy days are common
mostly out of NW• Sustained 15 to 30 MPH, • Gusts of
60 to 70 MPH
Temporary Runway
• PCC 1,000’ each end and Taxiway B• Asphalt remainder• Asphalt 1,000’ overruns, CTS shoulders• Sheet drainage to 200’ off centerline• New stake mounted R/W edge lights• Balanced earthwork varying elevation of
centerline profile & 3 T/W tie-ins• Used unsuitable in lower fill
Main Runway
• Existing PCC has ASR, 1953 construction• Remove and replace PCC• Add drainage layer and underdrain system• Remove edge lights (18” off edge) and replace
for paving track• Remove 6” of existing
subgrade for new pavement section
• 5 new plate load tests to verify subgrade
Temporary Pavement Design
• 20 year traffic reduced to 2 years in RFP
• Traffic Areas A, C and D
• PCASE used for thickness design
• Different asphalt/PCC and base thickness based on traffic area
• PCC flexural required 650, raised to 700 based on production 90 day breaks
• Reduce PCC thickness accordingly
Temporary Runway
Main Pavement Design
• Given 20-year traffic• Originally used 650 flex, changed to 700
and reduced thickness• Traffic Areas Type A, C and D • PCASE used for design thickness• Different PCC/Base thickness based on
Traffic type and drainage layer• USACE k of 250, low CBR’s, verify with
new Plate Load Tests when closed
Main Runway
Concrete Mix Design
• Mix design flexural beams didn’t show gain until 56 days
• Production mix gained much higher than mix design
• Using close to the minimum cement factor for durability
• Higher strengths are just happening
PCC Strength
Taxiway B Bypass
• drawing showing Bypass
Taxiway B Bypass
• Allowed 2 taxiways (A and B) to be closed• Designed asphalt for 60 days, hottest months• Reduced traffic for use in PCASE• Optimized pavement section by using
mechanistic software• Concerned about “punching” and rutting• Restricted B-52’s and Space Shuttle• Asphalt 4”, Base 7”• Performed fine, no rutting
Innovations
• Taxiway B Bypass• Grading Material Handling Plan• Grading models directly from designer to
GPS on earthmoving equipment• Tracking on PCC early based on Zero
Fatigue Curve Calculation edge stress• On-site computer server for rapid data
exchange, QC survey • No earthwork as-built survey, used models
Earthwork Affected Pavement
• Pre-watered the excavation areas
• Used an irrigation system
• Encountered some unsuitable (SC, CL,CH) and some unstable
• Required one footof suitable underpavement section
Asphalt Paving Challenges
• Crushed aggregate base through pug mill to add moisture
• Required 2 lifts, some delamination and drying out
• Approved to install inone lift
• Hot summer temperaturesdidn’t allow asphalt to cooldown for compaction
Concrete Challenges
• Hot summer temperatures required starting early, 5 AM most days
• Wind generally doesn’t start until after noon, so paving stopped
Aggregate Challenges
• Limited good pits for concrete aggregates
• Production limited for simultaneous use of concrete, asphalt, base and drainable base
• Some ASR, but mitigated with 15% Type F fly ash
Material Tests
• Cement tested in lab
• Fly ash tested in lab
• Asphalt oil tested in lab
• Purpose to verify vendor’s certificates
Construction Challenges
• Earthwork shrinkage more than anticipated
• Phasing of paving and lighting
• Asphalt compaction
• All work stops when winds over 25 knots (30 MPH)
TAXIWAY A
TAXIWAY B
TAXIWAY C
MAIN RUNWAY 04/22TEMPORARY RUNWAY
• Value Drivers– Flight Ops– Pavement
Quality - ASR– Environmental– Open
Communication– Inclusive
Decision-Making– Project
Performance Time/Budget
– Force Protection– Safety– Security
Guiding Precepts
Questions
Design Portion of D/B
• Design was an integrated member of the JV team
• Design was not a subcontractor or a subconsultant to the contractor
• Innovation and efficiency was expected and achieved
• No hidden agendas between design and construction
• Ideas were freely exchanged