The odd instance of four tunnels under a railway

First published in Branchline magazine, Bytown Railway Society, Inc., July/August 2026

Good engineering demands foresight. On the former Columbia & Western Railway across southern British Columbia, that principle was applied though not always with perfect success. Over 51 years, four successive tunnels were driven beneath the same railway embankment to carry water and road traffic. This unusual sequence forms our subject.

Roaring upgrade on Aug. 10, 1967, CP 4105 blasts black exhaust as it ignores the Greenwood highway underpass below. The road then took revenge: this C-liner was scrapped the following year; this section of the Columbia & Western was abandoned in 1991. The loco drags a mixed freight including wood chips for the pulp mill ahead at Castlegar. (Photo © Dave Wilke estate)

The C&W, later absorbed by the Canadian Pacific Railway, ran 126.6 miles west from Nelson to Midway over what railwaymen called “the Farron Hill", part of the Monashee Mountains and officially CP Rail’s Boundary Subdivision. Some today mistakenly fold it into the Kettle Valley Railway, to which it connected at Midway, but the C&W possessed a separate lineage.

My father worked steam over this route early in his career. I first visited it as a college student decades later, when the raised fill at Boundary Creek had already been pierced by twin highway tunnels. More than once I sounded my car horn as a crossing signal through the echoing underpass near Greenwood — in salute to his era and to the railway he served. Abandonment came in 1990, and with it the removal of the fill over the roadway — an end to the line and, save for recollection and a small family ritual.

The story begins in 1898, when the CPR purchased the C&W for its operating assets and for its charter which allowed extension of the line further west. By the next year that extension reached Grand Forks, and by 1900, Midway. The Boundary country was then in full industrial fervour. Numerous copper mines demanded rail haulage. Three smelters were blown in. Towns such as Phoenix, Deadwood, and Eholt sprang up with speculative confidence. Copper ore, with its varied industrial uses and ability to conduct electricity, promised riches comparable to the earlier Cariboo and Klondike goldfields.

Passenger service commenced on Sept. 18, 1899. The railway’s arrival brought a profound sense of accomplishment — and drew the attention of a rival, the American-owned Great Northern Railway. Both companies built spurs to isolated mines and prospered so long as the smelters smoked.

Timber was abundant. Ties, trestles, and water tanks were hewn from Douglas-fir, cedar, and Ponderosa pine. Just east of Greenwood the C&W crossed Boundary Creek on a trestle 795 feet (242 metres) long and 79 ft (24 m) high. Near one end the design incorporated a truss span of 150 ft (46 m) to cross Boundary Creek. However, on the opposite side of the valley, old photos show no accommodation for the road which was to come later, connecting the communities of Grand Forks, Eholt, Greenwood, and beyond. That road traffic grew to eventually became BC Highway 3.

This May 31, 1901 photo by the CPR’s engineer/photographer JW Heckman shows the Boundary Creek crossing about a year after its completion. Heckman’s notes reveal the trestle as 795 feet (242 metres) long by 79 ft (24 m) high. The truss spans 150 ft (46 m). (CRHA/Exporail Canadian Pacific Railway Company Fonds, 2468)

A CPR bridge crew sheathed the timber truss within this trestlework to lengthen its lifespan, probably anticipating it wouldn’t then need renewal prior to the upcoming infill. Viewing eastward, the far slope is where the 1913 concrete road tunnel was later built. (Greenwood Museum and Archives P00021)

Those early engineers planned for the creek under-crossing, but not the approach geometry. 

Trestle lifespans average 10–12 years before their wood needs renewal, although individual timbers would be replaced as needed before then. In an apparent effort to stretch the rebuild date, the Howe truss section was sheathed in planks. This would protect its members from some weather conditions, as well as from moisture penetration.

Time was up by 1913. The whole crossing was designated for infilling with rock and gravel. This eliminated ongoing maintenance costs, plus risks from wildfire and flood damage. It was at this juncture that the first two tunnels were constructed: one to pass Boundary Creek through the fill, and the other to protect the road which went through the bents. Those were common projects with trestle fills, but the structures exposed today took on unusual execution here.

At the lowest point of the valley, Boundary Creek had to be confined within an arched culvert with wing walls at each end to hold back the material which would eventually cover the height above. As usual, a CPR stonemasonry crew started the standard barrel arch to confine the creek within a tunnel of 25-foot width. This naturally was done before infilling began, so the creek could be diverted temporarily out of its natural bed (at the lowest elevation in the valley). That process is shown (at a different location) in my previous Branchline article “Building a Barrel Culvert,” Vol, 61, No. 1 (2022).

Strangely, the masons only laid the first few courses of granite block in parallel along the length needed. The rest, including the arched ceiling was concrete poured over formwork. This is an odd combination of material. Why so? One possible reason was that a separate crew was working on the nearby tunnel for the road. They were using concrete exclusively at a time it was still new technology.

By 1913, the CPR had largely switched to concrete construction as being faster, cheaper, and just as durable (if reinforced). It’s possible some highway engineer noticed that his concrete crew could take over completion of the creek culvert-in-progress and save time and money over the ancient trade labouring nearby. They would have had all the necessary equipment with them.

This staged photo is meant to demonstrate the function of the new underpass, but also demonstrates a collision hazard due to poor sight lines, even at low 1913 speeds! The cars are measured at 27.5 feet apart. The foreground car is thought to be a Buick model 32/35 Roadster, circa 1912–14. The car in the background is a McLaughlin Buick, license No. 1786. Thanks to Chris Garrish’s website on BC license plate history, we know that it originally belonged to Frank C. Buckless of Greenwood. S.H. McConnell of Rock Creek acquired it sometime after November 1912 and miners Morrison and Larson of Greenwood bought it in 1918. (Greenwood Museum and Archives P404)

The 1913 road tunnel had been forced into a compromised geometry in order to preserve the trestle underpinnings. Interestingly, its eroded edges now show protruding ends of rails. Such relay rails (see my Branchline article “Tales Told by Old Rails,” Vol. 59, No. 6, 2020) were undoubtedly of steel too lightweight or too worn to serve the heavier weights of freight progress.

An examination of the tunnel exterior shows its concrete shell as having indentations from CPR timber work, now rotted away. The road builders were obliged to choose an alignment beneath the trestle which crowded one of its angled bents. Neither could be moved, so the crew just poured concrete around the wood. Thus it was held in place and contributed to the strength of the arch it helped form. This is another instance where transportation engineers didn’t consider far enough into the future.

The tunnel alignment was straight, but needed a sharp curve at one portal. This impeded driver vision, and although diagonal hazard stripes were painted on the sides, collision risk was surely exacerbated by the increased speed of newer vehicles. The road became numbered as Highway 3 in 1941.

Fireman Cleland N. Parkin photographed at Midway, preparing to depart east to his home terminal at Nelson. En route he would cross Boundary Creek near Greenwood. Photo 1943 (© Frank A. Clapp estate)

The road tunnel was eventually designated as alternating one-way traffic, but modernity created another hazard. Transport trucks were being built longer and wider, and industrial loads were becoming higher. The only alternative was a long, non-local detour; time for a better design.

Thence came project engineer J. Greig Farstad in 1963. His employer, the Department of Highways (for whom I eventually worked as well), had designed modern-standard side-by-side tunnels at a new location right through the fill.

“Yes, we knew there would be an embedded trestle when we started. The contract allowed for variations and we certainly needed them. But we also had a plan. Soft ground tunnelling had known techniques. We were using Armco Multi-Plate as our lining,” Farstad told me recently. It was Armco’s methods and crew which was solidifying the ground under contract.

“We solidified the ground by driving horizontal needle-points, which were perforated pipes, in an arch shape the size of the proposed tunnel. Through those pipes we pumped a chemical grout with a fast solidification time. This set up our route sufficiently about 70 per cent of the time. Once the grout was solid, we dug out the loose fill which it surrounded in a horseshoe shape, and quickly erected the plating to protect our advance.”

In 1964, the earlier road route is still in use to the left, along with three new tunnel headings. Each heading contained footings for two multi-plate arches; the common centre footing plus outside footings for each. The structure was constructed proceeding east to west. This is the location of the east headwall. The barrels form part of the chemical pumping station. (Greenwood Museum and Archives P1077.03 by Greig Farstad)

Armco (today called Armtec), also had an engineer on site who invented a way of inserting and tightening the plate bolts from the inside. This was the first such project in the province, and Farstad knows of no other since. All the while the CPR drove trains overhead, unhindered.

“Digging was very slow. We had to continue grouting from the inside to prevent minor slumps. Then all those timbers had to be cut off. Like any innovators,” continued Farstad, “we argued and found solutions as we went. These couldn’t have been anticipated when the contract was written, so cost went way over budget. My final report made recommendations how to better handle such work in the future.”

Higher speed limits and safer transit are demonstrated in this March 1965 image of Highway 3. I drove through these tunnels dozens of times, often sounding my horn with a railway crossing salute in honour of my father, who once ran steam locos overhead. (Greenwood Museum and Archives P1078)

The old highway tunnel was then buried and the new highway tunnels functioned well for about three decades. However, CPR tracks through Boundary country were torn up in 1991, the line having been abandoned about a year earlier. It was acknowledgement of the triumph of roads over this famous rail route which once went westward to Hope via the Okanagan and Coquihalla valleys. With its demise went the need for the twin 38 m highway culverts. They were daylighted along with the buried highway tunnel of old.

Over the next five years, the odd, now above-ground tunnel beside the highway became covered in graffiti. Few knew what it was, or why it stood there. To mark the millennium in 2000, Greenwood mayor Arno Hennig sponsored a project to paint 210 national flags along its sides as a welcome to travellers. That brightened the structure briefly, but youthful artistic exuberance has since reasserted itself. An interpretive sign remains for those curious to learn the former C&W’s story.

Today, though one transportation link has vanished, another has emerged. As part of the Trans-Canada Trail, a rails-to-trails route descends at each end of the former embankment. Cyclists, walkers, and riders follow it across Highway 3 — now widely known as the Crowsnest Highway. Greenwood’s three tunnels mark our evolving use of transport for pleasure as well as profit and progress.

A century of work beneath this embankment shows how each generation believed it had planned for the future, only for new demands to overtake its designs. The masons, the early concrete crews, and the highway engineers all applied the best practice of their day, yet each solution proved finite. These tunnels stand — or once stood — to remind us that foresight is essential in engineering, but never complete.

Change always comes, and the works we leave behind are measured not only by how well they served, but how they can endure, adapt, or be re-purposed in the years that follow.

Tom Parkin has won five awards in the Canadian Railroad Historical Association and the US Railway & Locomotive Historical Society annual writing competitions. Read more of his work and contact him at tomwparkin.com

Informed Reading

• Burrows, Roger G. Railway Mileposts: British Columbia, Volume II: The Southern Routes … North Vancouver: Railway Milepost Books, 1984

• Turner, Robert D. and Wilke, J.S. David. Steam Along the Boundary: Canadian Pacific, Great Northern and the Great Boundary Copper Boom. Winlaw: Sono Nis Press, 2007

Note the protruding lightweight rails. Though the use of concrete was relatively new at this time, engineers here and elsewhere on the CPR were already experimenting with their own forms of rebar. (Photo © TW Parkin)

The exterior surface of the 1913 tunnel still shows where the concrete form builders were obliged to incorporate the outer sloping timbers of the vertical bents of the railway trestle. (Photo © TW Parkin)

The 2000 millennium painted flag project has all but succumbed to weathering and incomprehensible modern art. Inside the tunnel, skateboarders have built practise ramps. A new era has begun. (Photo © TW Parkin)

The author examines masonry details at the downstream portal of the Boundary Creek culvert. Both wing walls have been knocked down and the adjacent banks reinforced with rip-rap to prevent erosion during high water. The building stone is granite. (Photo © JS Thorne)

In 2024 the floor of the culvert was thickened with a new layer of concrete. Note how the foundation walls started with traditional stonemasonry, but the arched portion switched to concrete. This is the only example of mixed material which the author has yet seen. The plank formwork shows as longitudinal patterns above this intrepid railfan. (Photo © TW Parkin)

This 2006 image shows the start of undercutting and collapse of a downstream wing wall which led to remediation work 18 years later. No matter how well built (as this structure is), water is the single greatest threat to most architecture. (Photo © TW Parkin)