Ottawa Sun: Big trouble on Airport Pkwy. pedestrian bridge?
Ottawa Sun: $5 million footbridge delayed
Ottawa Business Journal: Concrete woes halt footbridge construction on parkway
the completion date has been blanked off and the million dollar decision made that the tower can't be repaired, it will have to be demolished and rebuilt. The delay costs will be borne by the Hunt Club community. The dollar cost seems to be borne by Bray at least for now; the city will be charging liquidated damages (penalty for late completion) starting 15 May. Negotiations with the concrete supplier Tomlinson concerning responsibility have ended for now with Bray choosing another supplier for concrete, Lafarge. The city project manager is now Luke Foley P.Eng.; the city closes down all communications with residents concerning the project and orders contractors and subcontractors to do the same.
Everything that follows in this account is my personal best estimates based upon what I could see from outside the construction fencing, supplemented on occasion by informal chats through the fencing, and upon public releases of information. Many of those public releases are due to the diligence of reporters for the Ottawa Sun and Ottawa Citizen and their financial support for Freedom of Information requests.
needs to come down
CBC: Airport Parkway bridge to be demolished and rebuilt
Ottawa Citizen: "Concrete problems mean city will tear down Airport Parkway bridge tower and start over"
News EMC: Troubled bridge to be demolished
demolition of the tower begins as the engineers commiserate with each other in the foreground. A green fabric shield protects cars using the parkway from dust and flying debris
Bray issues a public letter; the independent engineering company is A.Dagenais & Assoc. Inc.
work begins to assemble the concrete wall guarding the west approach pillars
demolition of the tower pauses; the remaining concrete will be saw cut along the line then the top lifted off to preserve the rebar that bonds the tower to the support pier. If this were not done, the pier would have to be largely demolished and replaced as well
saw cut completed, the last stage of tower removal is done by hand to minimize damage to the rebar. In 2013 this effort is judged inadequate; additional tying of tower to pier will be required
the approaches to the bridge are being built with light weight expanded polystyrene rather than rock fill. The underlying soil is weak marine silty clay; heavy rock fill would keep settling unpredictably for years. The blocks, about 2% the density of rock fill, will be staggered to distribute the light load over local soil weaknesses more than is possible with rock fill
News EMC: Footbridge a priority: councillor
the rebar to join the new tower to the pier is exposed ready for straightening and recoating (although no recoating is ever observed), the dust shield is removed, and forms for the tower are being returned to the site. The exceptionally thin deck cross section of the Genivar design is visible in the east approach span in the background; it is later found to be too thin and requires reinforcing to maintain structural integrity
the contractual date for 100% completion of the project
tower formwork rises again, hopefully for the last time
the polystyrene core of the west approach is now covered with a waterproof membrane and earth
work is proceeding very slowly; the stainless steel rebar has been delivered and installed, along with some of the foam formwork
after three weeks in which nothing has been done, work has restarted; questions from the public are not acknowledged by the city, Bray or Genivar
rebar is being installed and foam forms assembled.
stone is being packed down to be ready for the west approach form supports.
the new railway underpass is complete except for paving
formwork supports for the west approach arc are being installed; one of the lighting standards for the path is at the right
work continues on the west approach formwork; it's low priority compared to the tower
work starts on the north tower rebar
the formwork pillar support base is installed; the yellow pole is used to ensure the form follows the desired arc
rebar is now complete on the south side of the tower base, including the massive reinforcement around the stress-concentrating O-hole
precise positioning of the rebar forming the girdle around the O-hole is critical for tower strength; some of the complex constraining bars and ties are visible here, as are some of the brackets that will hold the O-hole lighting. The grey connecting rod is one of many that will hold the inside and outside faces of the form together; each needs to withstand up to 50 t tension during pouring due to the high fluidity of the concrete used
the floor formwork for the west approach is complete and side rebar installation is starting
the Genivar design requires three types of specialized rebar for this section; from left to right epoxy-coated iron, stainless steel, glass fiber-reinforced polymer
the north tower rebar is almost complete and outer face formwork is being assembled
side rebar is almost complete for the west approach
tower outer face formwork is being assembled
work continues on the inside tower formwork; no outer face has been installed yet
inspections complete, outer face formwork is being installed on the south side
a large storm drain under Highway 174 near Orleans collapses without warning, blocking a major traffic artery. Bray puts all its resources into rebuilding the drain and re-opening the highway as quickly as possible. Emergency crews work 24 hours a day, seven days a week to remove the collapsed metal culvert and instal a concrete replacement. 14 days after the car-sized sink hole was first reported, the road is paved and the highway is in full service for commuters. The original cost estimate to reline the culvert was $1.5 million; the emergency replacement cost $4.9 million
outer face formwork, almost complete on the north side, will await opening of Hwy 174
landscaping, by MacDonell's Landscaping of Cornwall, starts at the west end
the tower concrete is poured overnight to enable a continuous line of cement trucks to be used with minimal impact on Airport Parkway traffic. No one was notified in advance and no photos have ever been made available of this pouring. I was told quietly through the fence the next day that an SCC concrete testing expert was onsite throughout the pouring, that this time every truckload was tested individually (as I was taught to do at McGill in the early 1960s), that progress tests were done throughout the pour of the critical sections around the O-hole, and that test cylinders were cast for lab analysis to compare with the mockup tests
the deck of the west approach arc is poured
formwork for the west railings is being cleaned up
tie bars are being removed from the tower by old-fashioned muscle and hammer power
face forms are being removed from the north side
Joe Wheeler and other engineers anxiously check the surface finish and integrity - looks good
Success! Outer face formwork is off and everything looks go for the next phase. Bray personnel celebrate with a flag and hamburgers
under the first sleet of the season, concrete pads are being prepared to support the scaffolding for the upper half of the tower
the lower tower is free of all formwork; scaffolding is being erected to build the top tower
the west approach deck is still supported by formwork while it cures; formwork for the side beams is almost complete
Ottawa Sun: Airport Parkway Bridge back on track
scaffolding is taking shape to support the raised platform from which the top section of the tower will be built; some of the top-tower formwork is being worked on in the foreground. Built-in scaffold ladders are coated in yellow; two 40 m cranes are in use
the platform, 15 m up, is complete with storage shack, toilet and stairs; the rear form support for the top half of the tower is in place
30 m up, side form braces are being added with the help of one of Bray's new cherrypickers (blue) - it can reach 135' height and 70' sideways from its base
installation of the 15 m long vertical rebar for the top tower section begins. The top section of the tower is thick enough that regular iron can be used; it is being bent to the curve of the tower on site. Some of the rebar constraining loops can be seen on the platform
foundations are being prepared for the deck formwork over the parkway as a flagman stands by; earth that will cover a styrene-cored slope up to the wall can be seen behind
the east ramp is almost complete except for landscaping; formwork with brackets that will support working platforms for pouring the top tower is in front
work continues on the rebar for the top half of the tower; the stairwell is wrapped in plastic to reduce the wind chill during the climb; the wood latticework will support a plastic shroud to enclose the entire section and allow it to be heated while the concrete sets
styrofoam is being laid around the west pier so the bridge will appear to rise out of the earth
top section rebar complete, the front form face is being installed in drizzling sleet.
the access door from the pathway into the South Keys bus terminal has been completed; it's entirely glass both to light the hallway and to maximize visual openness of the pathway approach