paving in the high desert edwards air force base, ca tri-services conference april 23, 2008

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