Wednesday, July 26, 2017

West Toronto Diamond Grade Separation

West Toronto Diamond 2013 Bridge Move

The last Visited to the site was on December 20, 2015

At 2:30 am on September 1st, 2013, one of the critical parts of the grade separation took place when crews left the stagging area and headed to the diamond for removal of the existing tracks that was slated to start at 3:00 am.

This work would start with the removal of the temporary bridges supporting the CP Tracks over the new retaining wall for the tunnel as well the existing track and roadbed. Four meters deep of the existing roadbed had to be removed to get enough clearance to move a precast post tension deck span measuring 11m wide x 40m long x 900mm [36.1' x 131.2' x] thick weighing about 900tonne [992.1 tons] into position to not only support the current two tracks for the CP mainline, but for two more future tracks to support the future GO Transit Crosstown line.

This was no simple feat since this type of bridge has never been used in North America before. It is more like a Deck Span, but commonly used in Europe for High Speed Rail Lines.

The deck span was designed by Delcan Corporation as per their recommendation back in 2009 with Western Mechanical Electrical Millwright Services being responsible for pushing the deck span into position.

The deck span was built by Armtec who supplied 15 sections or precast slabs measuring in various widths x 11m [36.1 feet] long x 900mm [35.8 inches] thick and weighing about 60tonne [66.1 tons] each. The overall span was 11m x 40m [36.1' x 131.2'], weighing about 900tonne [992.1 tons]. It had two partly-built retaining walls on either side and room for future tracks. It was ballasted for the new tracks as well.

The deck span had 18 expansion bearing supports on each side that sat on steel and aluminum bronze slide paths to guide the deck span into position. These bearing supports were then bolted to the retaining wall since the deck span was to act as a lateral brace for the wall at this point given that there was no room to put in the top bracing tubes like the rest of the tunnel.

At the south end of the tunnel on the south side of the CP Tracks where the deck span bridge was to stop, there was an anchor post on either side to hold the cables that would be used to pull the deck span bridge down to it by twin hydraulic jacks on the north side of the deck span on each side.

CP requested a test move of the deck span on Friday to make sure it would move before giving final approval for removing its tracks. By doing so, the moving distance was a lot shorter than planned on September 1st.

The west retaining wall is also the centre wall and was built to support the deck span bridge for the second tunnel to the west. The retaining wall also had the sliding plate in position for the other deck span bridges and was encased in a wood frame box to protect it from the back filling, weather and construction. The protection would be removed near the time for the next move.

The removal of CP track 1 got underway at 3:00 am with track 2 scheduled for 5:00 am if the two trains scheduled for that window made it through the diamond by then. The clearance for track 2 was given at 4:50 am after five trains when through the diamond in place of the planned two.

CP maintenance crews disconnected the rail joints at the diamond and cut the rails on the east side of where the new bridge was to go. Once this was done, the track was removed along with the temporary bridges over the retaining wall for the bridge.

Once track 1 rails were removed, crews went to work to remove the temporary bridges over the retaining wall that would support the new bridge as well as the existing roadbed since it had to be 3m [9.8'] below the bridge to be moved into position, and to allow crews to work under it.

A number of unplanned issues arose and this delayed the removal of all the material before the deck span could be moved.

Even though the neighborhood was warned about the move well in advance and were told to expect noise during this work, a wake-up call went out a 6:45 am when the concrete support of the temporary track bridges had to be jackhammer to break it up so it could be removed.

Crews were digging the existing roadbed for the CP tracks as it needed to be 3m below the underside of the bridge so it could be moved into position and support for the retaining walls.

A 325- ton mobile crane was used to remove the tracks, temporary bridges, and the liners on both sides of the tunnel. It was also used to place floor plates on the floor of the tunnel so equipment wouldn't have to deal with the mud when moving from one area to another.

The scheduled call for the move to start was 1:00 pm, but it didn't start until about 4:00 pm caused by various issues.

During the day, CP crews dismantled the tracks that were removed along with the temporary wood bridges.

By 4:00 pm, the deck span was moving at about 22km/hour and was in .3m [1 foot] of final position when it stopped at 5:15 pm. They were hoping to get the speed up to 25km/hr and it never happened for some unknown reason. Crews were using a grease liquid on the track so the deck span bearing could slide along it. Measurements had to be taken to make sure the span was aligned correctly and in the right position as there was no way to pull this span back if it wasn't. At 9:15 pm, the deck span was in place.

The hydraulics system, which was specially built by Western Mechanical Electrical Millwright Services, could push the deck span with two or four jacks depending on how the jacks functioned and were controlled by a computer system and power sources. The speed to move the deck span was faster with the four jacks operating at the same time. Once the span started to move, and with the removal of the CP roadbed, there was no turning back nor time to fix the system if one of the jacks failed. This was why two jacks were used on each side. If one failed, the system would remove one on the other side so the remaining two could finish the move at a slower pace.

The deck span was backfilled to allow the new CP tracks to be installed on the new deck span as well access to complete the rest of the retaining wall. The lower level retaining walls where the Deck Span was built as well the area for the move was to be completed higher as needed as well having the tube bracing added to it at the top to match the rest of the retaining wall.

Crews would get to work finishing off building the rest of the retaining wall where the deck span sat before being moved into position.

NOTE: For a long holiday weekend, there was a lot more train traffic on the MacTier sub than normal with a number of trains backing in/out of the Lambton yard by the Wye. CP train crews were taking photos and video of the site as they passed the site.

The background image is of the new CP Bridge that is now being used by CP Trains. The 2nd bridge will go where this photo was shot on the Weston Sub.