Behind the Scenes: Visiting the Kichi Zìbì Mìkan Tunnel and Sherbourne Station

On April 12, 2024, Rail Fans Canada got an exclusive opportunity to see the progress in one of the Stage 2 West extension's most critical infrastructure projects: the Parkway Tunnel between Lincoln Fields and Kichi Zìbì Station.

Some background and context: The Kichi Zìbì Mìkan Tunnel (though the name is not official or formalized, it was previously referred to as the Parkway Tunnel before the renaming of the Parkway along the Ottawa River) is a 3 km long cut and cover tunnel being built between Kichi Zìbì Station and Lincoln Field. During the original Environmental Assessment (2013) for the West Extension of the Confederation Line, the city recommended and preferred a partially tunnelled solution as it would reduce costs of construction and shorten the project timeline.

The National Capital Commission (NCC), owners of the Parkway and surrounding lands, rejected this solution as it was seen to reduce access to the waterfront. Following a 100-Day Working Group, an agreement was reached between the NCC and the City of Ottawa in March 2015, which led to an agreement to build the guideway under the to-be relocated lanes of the John A Macdonald Parkway.

This solution ultimately led to the construction of an enclosed tunnel from Kichi Zìbì Station to Lincoln Fields.

Once completed, the Parkway tunnel will be the longest tunnel currently planned on the O-Train network.

The alignment of the Parkway Tunnel (Courtesy of the City of Ottawa)

Early works to prepare for the construction of the tunnel started in late 2019, including the temporary relocation of the Ottawa River Parkway, with the official groundbreaking ceremony on September 25, 2020. Given the geometry of the tunnel, as well as the soil through which it is being built, it is constructed using the cut-and-cover method along its entire alignment. At its deepest, the tunnel is approximately 10 metres below the surface.

The construction of the tunnels (The same technique is also being used for the Connaught Tunnel further West) for the O-Train West Extension Project employs the traditional cut and cover method, one of the oldest tunnelling techniques. This is different to the method used for the downtown tunnel which involved rock mining using road-headers.

The process of building each cut and cover tunnel section involves several key steps. Initially, heavy machinery such as excavators or backhoes is employed to excavate the trench along the intended tunnel path.

Subsequently, the tunnel structure is erected within this trench, using concrete and steel tailored to project specifications, as well as waterproofing layers to ensure the long-term integrity of the structure. Once the structure is established and stabilized, the trench is filled in, restoring the surface above, which may include backfilling with soil.

Finally, the surface restoration process, including work on the Kichi Zìbì Mìkan and Richmond Road, is to be undertaken to complete the project.

The first significant milestone of the project was reached in October 2023 with the completion of the excavation for the tunnel. This required the extraction of more than 400,000 cubic metres of earth.

As of our visit, the tunnel was at 85% completion, with backfilling well underway, as well as most of the tunnel structure. Completion of the structure and backfilling is expected to be completed in the Summer of 2024.

Over the coming months, construction of the guideway will expand throughout the tunnel with the construction of the track plinths, rail installation, overhead catenary system and control systems by late 2025, allowing for testing to begin in early 2026.

Fall 2020 (Courtesy of the City of Ottawa)

Summer 2021 (Courtesy of the City of Ottawa)

Winter 2024 (Courtesy of the City of Ottawa)

During our visit, we had the opportunity to explore the tunnel from its eastern portal, a few hundred meters west of Kichi Zìbì Station, to the future Sherbourne Station. Given the length of the tunnel and project sequencing needs, we had the opportunity to see the various stages of progress that the tunnel is in at this time. A snapshot if you will!

Given the location of Kichi Zìbì Station in the former Transitway trench, the portal leading to the tunnel connects the different elevations between the Transitway and the necessary depth of the tunnel, and the new alignment used by the O-Train.

The tunnel itself is designed as a single trench, with two separate corridors, one per direction of travel, with a central wall separating both tracks. Given the length of the tunnel, active ventilation will ensure a supply of fresh air during regular operation, as well as for emergencies situations. There is also a few passageways between the two corridors should evacuation be required. There is no doubt: the scale of this project is massive, with various residences in proximity, an arterial road above and around most of the worksites as well as the numerous technical considerations that come with building a tunnel cut-and-cover tunnel through active neighbourhoods.

Approaching the portal from above, you can see the location of Kichi Zìbì Station in the distance.

Looking further west, you can see the structure of the future Kichi Zìbì Station.

Looking eastward. In the distance, Kichi Zibi Station and the Transitway Trench

Looking down at the tunnel portal. Notice the layout of the tunnel: one structure with an innner wall seperating the two tracks.

A closer look at the tunnel portal.

Once you get inside the tunnel, the size of the tunnel is immediately noticeable. Large enough to accomodate the Citadis Spirit LRV, and necessary equipment, it feels cavernous. Stading at the portal, the straight line of the tunnel along the Parkway allows you to see all the way down to the curve where it goes towards the Byron Linear Park. As progress throughout the tunnel is done in stages, we get to see various states of progress to allow for track installation in the coming year.

Along this stretch, the tunnel structure has already been completed, with work progressing on the plinths that will support the installation of tracks. Using a direct fixation system, similar to the one used on other sections of the Confederation Line (one noticeable spot is the tunnel portal in the trench next tu uOttawa station), the tracks are directly attached to the concrete foundation. Since there is two sets of tracks, this means there is a total of 6 kilometres of plinths, anchors and tracks to install in the tunnel, in addition to the various systems required for safe operation of the line once it opens: OCS, fire suppression, signaling / control system, mobile connectivity, ventilation, access walkway, drainage... It is a lot of things to consider!

On the right, you can see the various steps of progress in the construction of one of the two track plinths. The "darker" grounded concrete is the location of the second track plinth. In between the two plinths, drainage will be installed. The space to the left (next to the centre wall of the tunnel) will be used for signaling cabling and other equipment, as well as the access / egress walkway.

A section of the tunnel before the installation of the plinth's rebar. On the right, you can see the machine which grounds the surface layer of the concrete to allow for a stronger bond of the plinth to the tunnel structure. The elevated roof will allow for the installation of the necessary ventillation equipment necessary for the safety of the tunnel.

Before the formwork and concrete is poured, the rebar is progressively installed.

A closer look at mostly completed rebar installation.

Being positioned on this picture, the anchors which will attach the rail to the concrete plinth.

While in most locations the geometry of the tunnel is relatively even, there are various sections that feature more difficult elements to construct: curves, wider sections to accommodate the stations, elevation changes, etc. As a result of those characteristics, different methods were used to build the structure of the tunnel.

For most of the tunnel, East West Connectors uses the Everest Traveler Formwork System which allows for construction of all three walls and roof of the tunnel in one step once the concrete base of the tunnel is completed. This system uses specialized formwork equipment that can be moved along the path of construction and supports the concrete and rebar until it has solidified. Once done, the system can be moved, removing the need for the teardown and installation of concrete formwork throughout the alignment.

Given the different geometry of the tunnel in some locations, more than one machine was used during construction, including one that is able to build the curved sections of the tunnel. Given the progress of the tunnel during our visit, we were not able to see one of those machines, though you can one in our exclusive video visit of the future Lincoln Fields Station and the other end of the Parkway Tunnel.

For sections where the geometry of the tunnel changes, particularly while approaching the future Sherbourne and New Orchard station where the tunnel widens, such a system could not be used. As such, manual formwork and pouring was required to ensure the geometry of the tunnel was suitable. During our visit, we were able to walk through one of the remaining opened section of the tunnel which is being built this way. By looking close at the following picture, you can clearly see where the concrete form differs from one method to the other.

You can see the transition from the Everest formed tunnel to the manually built section. Rebar is exposed while awaiting the construction of the roof of the tunnel and its related rebar.

Further ahead, rebar is being installed along the formwork to prepare for the final concrete pour.

A view at the supports keeping the trench open until the final structural element is built. You cal also see the suspended pipes and cables which were displaced for construction.

From the approximate height of the tunnel roof, you can see the backfilling of the completed section, as well as the relative proximity to the surface.

At street-level, looking down at the pipes and wiring being suspended over the open tunnel trench.

At street-level, the rebar which will form the roof of the tunnel is being finalized before the final concrete pour. Once hardened and waterproofed, backfilling will be able to proceed.

In addition to this look at the progress on the Parkway tunnel, we had the opportunity to get a closer look at the progress of Sherbourne Station. Integrated within the tunnel, the station will remain an open trench and serve as ventilation for the tunnel, as well as to reduce the complexity of construction.

Given the location of the station in the middle of the Byron Linear Park, between Byron Avenue and Richmond Road, the layout of the station is composed of one entrance located towards Sherbourne Road. At the other end of the station, a mechanical room will contain various HVAC and electrical systems required for operations.

As of the time of our visit, structural formwork and the installation of rebar is ongoing to build the floor of the entrance building, as well as the central platform where passengers will wait for the trains. The station will be very similar in design to the other station being built in the tunnel, New Orchard. Once the concrete work is completed, we can expect to see the structural steel to be installed, creating the general shape of the station.

A crossection of Sherbourne Station once completed.

Satelite image of Sherbourne Station - March 2024. The station entrance will to the right on this overhead view. The mechanical building structure will be over to the west (left) end of the station area.

Looking towards Sherbourne Road, formwork is ongoing to build the station entrance platform. You can also see the drainage trench (covered by plywood), as well as the rebar for the central platform.

A closer look at the central platform rebar and utility piping installation.

Looking west towards the future mechanical building. Notice the exposed rebar which will be completed in the near future to allow for electrical and mechanical work to start.

The central grey beams on those pictures are part of the permanent structure of the station, unlike the beams seen in previous locations. The platform will be in the open trench, with some covered areas for inclement weather.

A render of the rehabilated Byron Linear Park and the Station Entrance once completed. To the left of the trench, you can see the mechanical building.

Given the importance of the Byron Linear Park in its community, it is in the current scope of the project to renew and restore the linear park above the completed tunnel. Once completed, it will include a variety of public art, more trees than before construction and a public plaza for community events. The NCC and the City will also collaborate to renew the Ottawa River parkway once tunnel construction is completed, with new pathways and spaces for people to enjoy.

It is important to remember that construction of the tunnel started during some of the most intense time of the pandemic, three and a half years ago. The progress on the three kilometres tunnel is impressive to see in-person, especially considering that, in a few years, passengers will be able to ride the O-Train all the way from Trim to Algonquin College and Moodie. We are looking forward to sharing more of the progress of the O-Train Stage 2 project in future videos and articles. If you haven't done so, make sure to watch the accompanying video with additional information and footage from the tunnel!

Special thanks to the City of Ottawa, East West Connectors and the staff on-site for allowing us this very special behind the scenes look at one of the largest infrastructure project in the city.