Bridge over BNSF Railroad 7 km East of Windham - East

Bridge Replacement Project Using Accelerated Bridge Construction

Project Location

Existing Bridge

o o o 3-Span Concrete Tee Beam 123 Feet Long 28 Feet Wide

Approach Looking Southeast

Profile Looking Southwest

Design Parameters

o o o o o o o 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

o o o o o o 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?

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 o o o 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?

o o o o o

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

o o o o o Contacts with o o Town of Hobson - Mayor Hobson School o o o o County Commissioners Trucking Industry – grain elevator Air Force Base BNSF Railroad Road User Cost Calculations Preliminary ABC Ideas Contract Time Estimates Local Events

– Hay Days – Utica Montana

What can we accelerate?

What portion of construction takes the most time?

o o o o o o 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

o Foundations o o What can we do while traffic is on existing bridge?

What foundation types will work?

o Forming and curing bent caps o o What cast-in-place can be done while traffic is on existing bridge?

Precast end and intermediate caps?

o Deck forming and curing o Full-depth precast deck panels o o Partial-depth Stay-in-place Forms

Divided Work Into Stages

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

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 Detour

Day 1 o o Removed span 2 deck and beams Removed span 3 deck

Day 2 o o o Removed span 3 beams Removed bent 3 and 4 Removed span 1 deck

Day 3 o o o o Bent 4 – drove piles, formed and placed cap Bent 3 – Set cap and placed closure Removed span 1 beams Removed bents 1 and 2

Precast Pier Cap

Day 4 o o Bent 2 – Set cap Bent 1 – drove piles

Day 5 o o Bent 2 – placed closure Bent 4 –formed and placed cap

Day 6 o Span 3 – Set girders and deck panels

Day 7 o Sunday – no work Day 8 o Span 2 – Set girders and deck panels

Day 9 o Span 1 – Set girders and half the deck panels Day 10 o o Span 1 – Set remaining deck panels Began forming closure pours

Day 11 o o Bents 1 & 4 – Formed and placed backwalls Formed deck panel closure pours Day 12 o Continued forming deck panel closure pours Day 13 and 14 o Saturday and Sunday – No work Day 15 o o Adjusted deck grades Prepare for deck closure pours

Day 16 and 17 o UHPC Closure Pours

Day 18 and 19 o o Removing form work and grinding joints Fill low spots

Day 20 and 21 o Weekend no bridge work – building approach fills Day 22 o More grinding and approach fills Day 23 o o Tying barrier steel Test run with slip form Day 24 o Approach work Day 25 o o Slip formed barriers Final grading along RR tracks

Day 26 and 27 o o More grading work Approach rails Day 28 o 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 o o o o 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 [email protected]

406-444-7610