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Bridge over BNSF Railroad
7 km East of Windham - East
Bridge Replacement Project Using Accelerated Bridge Construction
Project Location
Existing Bridgeo 3-Span Concrete Tee Beamo 123 Feet Longo 28 Feet Wide
Approach Looking Southeast
Profile Looking Southwest
Design Parameterso National Highway Routeo 2500 vehicles per day (23% Trucks)o Major truck route between Great Falls and Billings o US Air Force Missile Routeo Grain Elevator in Moccasin o BNSF Railroad Crossingo Accident cluster at bridge
New Bridge Requirements
o New width = 40 feeto Increased railroad lateral clearanceo Increased railroad vertical clearanceo Avoid existing foundations (timber piles)o Minimize grade raise to catch slopes on
existing approaches – avoid sliver fills and new R\W
o Minimize traffic disruptions
What are our options?o New Bridge on Offset Alignment
o New Bridge on same alignment using On-site Detour
o New Bridge on same alignment using Phase Construction
o New Bridge on same alignment using Off-site detour and ABC
Could Accelerated Construction work
here??o How long can we shut down bridge site?o How quickly can we build a new bridge?o How much building can be completed before with
existing bridge in place?o Is there a reasonable detour route?
Possible detour route
o Secondary Highways – wide shoulders / flat slopeso Similar detour length for thru-traffico Detour through town of Hobson – school crossingo At-grade RR crossing in Hobsono Many local detours possible (County Roads)
o Contacts with o Town of Hobson - Mayoro Hobson Schoolo County Commissionerso Trucking Industry – grain elevatoro Air Force Baseo BNSF Railroad
o Road User Cost Calculationso Preliminary ABC Ideaso Contract Time Estimateso Local Events
ABC Planning Efforts
– Hay Days – Utica
Montana
What can we accelerate?What portion of construction takes the most time?
o Foundation construction – 4 days/shaft or 4 piles/day
o Drilled Shaft testing – 14 days before testing / longer if problems are encountered
o Forming bent caps – 3 days eacho Curing bent caps – 15 days per projecto Deck forming – 20 days up to 300 feeto Deck curing and sealing – 28 days
Allowing for some overlap……80 days for major items
Potential Solutionso Foundations
o What can we do while traffic is on existing bridge?o What foundation types will work?
o Forming and curing bent capso What cast-in-place can be done while traffic is on existing bridge?o Precast end and intermediate caps?
o Deck forming and curingo Full-depth precast deck panelso Partial-depth o Stay-in-place Forms
o What could be completed before detouring traffic
o What would be accelerated while traffic is on detour route
o What work could be done after traffic is moved back on new bridge
Divided Work Into Stages
Work Prior to Detouring Traffic
Drilled 4 shafts outside the bridge limits and behind the existing intermediate bents.
Cast struts/crash wall on top of and between shafts
Cast walls on top of struts
Traffic on DetourDay 1o Removed span 2 deck and beamso Removed span 3 deck
Day 2o Removed span 3 beamso Removed bent 3 and 4o Removed span 1 deck
Day 3o Bent 4 – drove piles, formed and placed capo Bent 3 – Set cap and placed closureo Removed span 1 beamso Removed bents 1 and 2
Precast Pier Cap
Day 4o Bent 2 – Set cap o Bent 1 – drove piles
Day 5o Bent 2 – placed closureo Bent 4 –formed and placed cap
Day 6o Span 3 – Set girders and deck panels
Day 7o Sunday – no work
Day 8o Span 2 – Set girders and deck panels
Day 9o Span 1 – Set girders and half the deck panels
Day 10o Span 1 – Set remaining deck panelso Began forming closure pours
Day 11o Bents 1 & 4 – Formed and placed backwallso Formed deck panel closure pours
Day 12o Continued forming deck panel closure pours
Day 13 and 14o Saturday and Sunday – No work
Day 15o Adjusted deck gradeso Prepare for deck closure pours
Day 16 and 17 o UHPC Closure Pours
Day 18 and 19o Removing form work and grinding jointso Fill low spots
Day 20 and 21o Weekend no bridge work – building approach fills
Day 22o More grinding and approach fills
Day 23o Tying barrier steel o Test run with slip form
Day 24 o Approach work
Day 25o Slip formed barrierso Final grading along RR tracks
Day 26 and 27o More grading worko Approach rails
Day 28o Finished approach rails
Day 29 o Opened to Traffic
One day ahead of schedule (incentive/disincentive deadline)
Now lets see that in fast motion
Lessons Learned
o Project scheduling was intensiveo Design details are critical – things need to fito Allow adequate tolerance on precast elementso UHPC is difficult to grind – reduce exposed area to
minimize grindingo Have an Engineer on site during construction of
critical elements – be prepared to make decisions
