The Coquihalla railway link, operated by the Kettle Valley Railway (KV), a Canadian Pacific Railway (CP) subsidiary, connected the Coquihalla Summit and Hope in southwestern British Columbia. This standard gauge trackage, which followed the Coquihalla River through the North Cascades, formed the greater part of the KV Coquihalla Subdivision.

Proposals and planning During surveys for a transcontinental railway route in the 1870s, Sandford Fleming estimated of aggregate tunnelling and severe gradients would be required for a Coquihalla route.

When surveying alternative east–west routes over the passes (namely Allison (longest), Coquihalla, and Railroad (shortest)) in 1902, Edgar Dewdney rejected all of them in favour of rails via Spences Bridge. Around 1900, the Columbia and Western Railway (C&W), a CP subsidiary, had projected a line to connect Princeton and Penticton via Keremeos, but this never eventuated. CP's Thomas Shaughnessy claimed he would build a direct Kootenays to the coast line, but the chosen route was more suited to local traffic. Chief engineer Andrew McCulloch was not given the freedom to select the optimal route.

By 1910, the CP and Great Northern Railway (GN), had each surveyed routes through the Coquihalla canyon. GN's James J. Hill planned a tunnel under the mountain between Tulameen and Portia, because negotiating Railroad Pass without a tunnel was impractical. Exiting on the east side of the Coquihalla River, this tunnel would not have interfered with earlier and later trails and roads. Extreme weather proved to make the upper Coquihalla canyon extremely expensive to maintain. Such a tunnel would not only protect against these weather-related issues but would be shorter. After calling for tenders, GN ultimately chose the longer Coquihalla Pass route instead.

The CP route via Osprey Lake (Bankeir) and Brookmere was not optimal. A sounder choice would have been southwest to the Similkameen River and northwest to a Railroad Pass tunnel. To bring into being this tunnel option, a compromise between CP and GN should have been forced upon both parties earlier. Instead, the CP and GN conflicts over the narrow Coquihalla right-of-way triggered years of legal claims. In November 1913, they signed the Coquihalla Agreement, whereby CP would build and maintain the Coquihalla line, but GN would receive running rights. In early 1914, they signed the Tulameen Agreement, whereby GN would be responsible for Princeton–Brookmere, upon which CP would have running rights.

In 1937, John Sullivan wrote to McCulloch, both retired senior CP employees, stating, "Of all the blunders in railway building history the CPR's southern British Columbia rail line (namely the KV) is the greatest".

Construction In harsh weather, scree forms an unstable building base. In the upper canyon, the railbed lay at the transition from semi-solid rock to scree. The latter provided the outer part of the rail bed, while the inner part was cut from the rock face. Construction crews returning in spring 1916 needed first to repair much of the 1915 construction work that had been destroyed by slides over the winter.

The maximum gradient was 2.2 per cent. Construction costs were $136,000 per mile, five times the average cost for Canadian railways in 1913. One particular mile in the upper canyon cost $300,000, being one of the most expensive miles of railway built up to that time. The provincial construction subsidy was $10,000 per mile.

The last spike on the KV was driven in July 1916 east of the tunnel adjacent to the Ladner Creek bridge.

Operation and maintenance Regular passenger service began at the end of July 1916. Eastbound trains took on pusher engines at Hope.

Washouts and slides closed the Coquihalla during December 1917–May 1918, January–May 1921, 2 to 4 months in 1930s, and 6 months in 1938–39. During World War II, Japanese Canadians from the Tashme Incarceration Camp formed a bridge and building maintenance gang. Having barely recovered from the damage of the previous winter, the line again closed in fall 1949.

In 1926, CP was making plans to abandon the Coquihalla route, following a series of slides. Even if an abandonment received government approval, CP might have been required to return government construction subsidies and would also forfeit the annual fee paid by GN. When slides and washouts in 1932 resurrected thoughts of abandonment, the ongoing GN payments were the deciding factor. Severe weather damage in early 1939 raised concerns again, but the likelihood of an escalating war in Europe, which would increase rail traffic, instead prompted extensive upgrades.

For a line it had never commercially used, GN had paid CP $150,000 annually since 1916, and CP had paid GN $60,000 annually for actual use. In 1944–45, to end such payments, GN paid $4,500,000 to CP to terminate the Coquihalla Agreement. In turn, CP paid GN $1,500,000 to terminate the Tulameen Agreement and acquired that leg.

During World War II, bulldozers were introduced for snow clearing, which proved superior to the prior combination of rotary and wedge plows. In addition, substandard snowsheds were removed rather than replaced, resulting in 10 of the original 15 sheds being demolished over an eight-year period.

Not a single passenger was killed during the lifetime of the railway. A speeder checking for slides and washouts preceded every passenger train through the Coquihalla Pass. In winter, a plow train preceded the speeder. In addition, foot patrols checked the whole route every day.

In 1952, passenger train schedules were changed by 12 hours, meaning the Coquihalla was travelled during daylight. In 1954, the passenger schedule reverted to night time travel through the area. After the November 1959 slides and washouts in the vicinity of Jessica, passenger service through the Coquihalla permanently ceased that month.

Timetables

CP Train Timetables (Regular stop or Flag stop) Mile 1916 1919 1929 1932 1935 1939 1943 1948 1954 1959 Hope 162.7 Reg. Reg. Reg. Reg. Reg. Reg. Reg Reg. Reg. CNRCrossing 162.2 Flag Othello 157.2 Flag Flag Flag Flag Flag Flag Flag Flag Lear 153.3 Flag Flag Flag Flag Flag Flag Flag Flag Jessica 148.2 Both Reg. Flag Flag Flag Flag Flag Flag Aurum 146.7 Flag Flag Portia 142.6 Flag Flag Reg. Reg. Reg. Both Both Flag Flag Iago 137.9 Flag Flag Flag Flag Flag Flag Flag Flag Romeo 132.2 Flag Flag Flag Flag Flag Flag Flag Flag Coquihalla 126.1 Reg. Reg. Reg. Reg. Reg. Reg. Both Flag Flag

Infrastructure and incidents

KV infrastructure and incidents for Coquihalla–Romeo Mile Place Passenger Service Station Building Section House SectionCrew Storage Capacity EngineHouse Track Ref. Type Built Closed Comments Built Comments From To WaterTank CoalChute Passing Other The Juliet–Coquihalla table of the Coldwater River former railway trackage is the adjacent segment. 17.2 Wye: Operational Jul 1916 to Jul 1961. Mainly used for turning pusher engines from Hope during 1916–c.1930. Sited about south of present Britton Creek Rest Area. The northeast leg of the wye is the beginning of present Tulameen FSR. 17.2 By yearend 1913, the westward advance of the KV rail head from the Brodie Station reached this point, where it remained until tracklaying recommenced in late summer 1914. 18.0 Coquihalla Jul 1916to Nov1959 Small shack c.1916. just north of water tank. 1961 Removed after 1961. Likely built 1915 just south of water tank. Building removed after 1972. Foundation remains. 1916 Dec 1959 aligned with present Coquihalla Lakes Lodge. Deactivated 1954. Foundation remains. None Two-stall built 1917 (aligned with north end of Upper Lake). Later demolished. Jul 1916 toJul1961.Length Coquihalla Lakes Road largely follows the KV rail bed to Mile 18.7, as does the Trans Mountain Pipeline private road to Mile 19.6. At this point, the road leaves the KV rail bed, which is impassable and dangerous, but visible in places on the hillside above. 19.7 Tunnel #1: timber lined. Concrete portals added at west end in 1947 and east end in 1951. 19.7 Tunnel #2: length. Concrete portals added in 1943. Since collapsed. 20.3 Tunnel #3: length. Concrete portals added at west end in 1948 and east end in 1941. Since collapsed. 20.5 Sweeney's Cut. 20.6 Gulch: timber frame trestle. Rebuilt in 1947. Removed. 20.7 Gulch: timber frame trestle. Rebuilt in 1947. Army demolition exercise blew up in Sep 1969. 21.0 In early Oct 1914, the westward advance of the KV rail head from the Brodie Station reached this point. 21.0 Gulch: box culvert. Replaced by timber frame trestle in 1948. 21.2 Falls Creek (Bridal Veil Falls to northwest): timber frame trestle. Replaced by timber frame trestle and steel deck lattice span c.1927. Collapsed winter 1995–96. 21.4 Hayden's Cut: Unstable rock prevented tunnel. Presumably named after conductor Augusto Taylor Hayden, who died in Nov 1916 when a rockslide smashed into a snowplow unit in the vicinity. 21.5 Gulch: timber frame trestle. Destroyed by forest fire in 1938. Snowslide took out in 1949. Later removed. 21.7 Tack Creek: timber frame trestle. Replaced by steel deck plate girder spans in 1954. Partially dismantled when rails lifted in 1962. Steel towers remain. 22.2 Gulch: timber frame trestle of unknown dimensions. 22.3 Gulch: timber frame trestle. Destroyed by forest fire in 1938. Replaced by fill in 1952. 22.5 Tunnel #4: length. Concrete portals added at west end in 1945 and east end in 1942. Collapsed in May 1959. Replaced by diversion around the mountain. 22.7 Cultus Creek: timber frame trestle. Removed c.1970. 23.1 Tunnel #5: length. Concrete portals added at west end in 1945 and east end in 1939. 23.2 Gulch: timber frame trestle. Removed. 23.3 Gulch: timber frame trestle. Removed. 23.5 Tunnel #6: length. Concrete portals added at west end in 1942 and east end in 1946. 23.5 Water: open tank on the northwest side of the main line. Deactivated late 1940s. Mostly emergency water supply. 23.6 Unnamed creek: timber frame trestle. Rebuilt in 1948. Removed. 23.8 Snowshed #1: length. Extended by in 1917 and in 1918. Removed in late 1945.