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Bridge over BNSF Railroad 7 km East of Windham - East. Bridge Replacement Project Using Accelerated Bridge Construction. Project Location. Existing Bridge. 3-Span Concrete Tee Beam 123 Feet Long 28 Feet Wide. Approach L ooking Southeast. Profile L ooking Southwest. Design Parameters.
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Bridge over BNSF Railroad7 km East of Windham - East Bridge Replacement Project Using Accelerated Bridge Construction
Existing Bridge • 3-Span Concrete Tee Beam • 123 Feet Long • 28 Feet Wide
Design Parameters • National Highway Route • 2500 vehicles per day (23% Trucks) • Major truck route between Great Falls and Billings • US Air Force Missile Route • Grain Elevator in Moccasin • BNSF Railroad Crossing • Accident cluster at bridge
New Bridge Requirements • New width = 40 feet • Increased railroad lateral clearance • Increased railroad vertical clearance • Avoid existing foundations (timber piles) • Minimize grade raise to catch slopes on existing approaches – avoid sliver fills and new R\W • Minimize traffic disruptions
What are our options? • New Bridge on Offset Alignment • New Bridge on same alignment using On-site Detour • New Bridge on same alignment using Phase Construction • New Bridge on same alignment using Off-site detour and ABC
Could Accelerated Construction work here?? • How long can we shut down bridge site? • How quickly can we build a new bridge? • How much building can be completed before with existing bridge in place? • Is there a reasonable detour route?
Possible detour route • Secondary Highways – wide shoulders / flat slopes • Similar detour length for thru-traffic • Detour through town of Hobson – school crossing • At-grade RR crossing in Hobson • Many local detours possible (County Roads)
ABC Planning Efforts • Contacts with • Town of Hobson - Mayor • Hobson School • County Commissioners • Trucking Industry – grain elevator • Air Force Base • BNSF Railroad • Road User Cost Calculations • Preliminary ABC Ideas • Contract Time Estimates • Local Events
What can we accelerate? What portion of construction takes the most time? • Foundation construction – 4 days/shaft or 4 piles/day • Drilled Shaft testing – 14 days before testing / longer if problems are encountered • Forming bent caps – 3 days each • Curing bent caps – 15 days per project • Deck forming – 20 days up to 300 feet • Deck curing and sealing – 28 days Allowing for some overlap……80 days for major items
Potential Solutions • Foundations • What can we do while traffic is on existing bridge? • What foundation types will work? • Forming and curing bent caps • What cast-in-place can be done while traffic is on existing bridge? • Precast end and intermediate caps? • Deck forming and curing • Full-depth precast deck panels • Partial-depth • Stay-in-place Forms
Divided Work Into Stages • What could be completed before detouring traffic • What would be accelerated while traffic is on detour route • What work could be done after traffic is moved back on new bridge
Work Prior to Detouring Traffic Drilled 4 shafts outside the bridge limits and behind the existing intermediate bents.
Traffic on Detour Day 1 • Removed span 2 deck and beams • Removed span 3 deck
Day 2 • Removed span 3 beams • Removed bent 3 and 4 • Removed span 1 deck
Day 3 • Bent 4 – drove piles, formed and placed cap • Bent 3 – Set cap and placed closure • Removed span 1 beams • Removed bents 1 and 2
Day 4 • Bent 2 – Set cap • Bent 1 – drove piles
Day 5 • Bent 2 – placed closure • Bent 4 –formed and placed cap
Day 6 • Span 3 – Set girders and deck panels
Day 7 • Sunday – no work Day 8 • Span 2 – Set girders and deck panels
Day 9 • Span 1 – Set girders and half the deck panels Day 10 • Span 1 – Set remaining deck panels • Began forming closure pours
Day 11 • Bents 1 & 4 – Formed and placed backwalls • Formed deck panel closure pours Day 12 • Continued forming deck panel closure pours Day 13 and 14 • Saturday and Sunday – No work Day 15 • Adjusted deck grades • Prepare for deck closure pours
Day 16 and 17 • UHPC Closure Pours
Day 18 and 19 • Removing form work and grinding joints • Fill low spots
Day 20 and 21 • Weekend no bridge work – building approach fills Day 22 • More grinding and approach fills Day 23 • Tying barrier steel • Test run with slip form Day 24 • Approach work Day 25 • Slip formed barriers • Final grading along RR tracks
Day 26 and 27 • More grading work • Approach rails Day 28 • Finished approach rails Day 29 • Opened to Traffic One day ahead of schedule (incentive/disincentive deadline)
Lessons Learned • Project scheduling was intensive • Design details are critical – things need to fit • Allow adequate tolerance on precast elements • UHPC is difficult to grind – reduce exposed area to minimize grinding • Have an Engineer on site during construction of critical elements – be prepared to make decisions
Questions?? Project Contact: Jeff Olsen jolsen@mt.gov 406-444-7610