4 years ago we drove highway 5 along your proposed route. That road is has a steep grade that goes on for miles. Many of the semi's were in first gear crawling along at 5 to 10 mph. We had a Toyota MH with a 4 cylinder engine. I kept the rpm's up and maintained 25 to 30 mph in first gear. I could not get into second gear because my rpm's would drop too low and my speed started to drop. As a result, I drove in first gear and was happy to actually be passing someone,something that didn't happen often.
This is a write-up about the road from this site: https://www.dangerousroads.org/north-america/canada/4008-coquihalla-highway.html
Coquihalla Highway is an extreme freeway located in southern British Columbia, Canada. It’s part of the Highway 5 and is around 200km long. It’s one of the worst roads in all of North America in winters. There were 32 fatal crashes between 2004 and 2013 (according to ICBC). In spring, summer or fall, it's a breeze, but in winter there are at least 400-500 accidents and plenty of fatalities.
Trucks have been known to avoid the route due to the long, steep climb up to the summit and the long, steep descent, but most motorists don't have any hesitation about driving the route in spring-summer-fall conditions. Winter driving is indeed dangerous, but that is more a reflection of the high elevation and mountainous terrain rather than the road itself. To quote Highway from Hell's Jamie Davis, “I can’t criticize the Coquihalla. The main factor is you’re driving over a mountain. It’s not a flat road, it’s a mountainous highway... It requires skill to drive.” At high elevations it can sometimes get to be -30 deg. C in cold winter weather. The highway is pretty good, some sections have frost heaves and uneven pavement but it's 2 lanes each way so slower traffic like trucks are not an issue.
This asphalted road is the main highway link between Kelowna in the Okanagan Valley and Vancouver B.C. Make sure you get your vehicle and yourself well-prepared before driving this road. It is very steep at both ends and although it is a modern highway, most truckers avoid traveling on it due to the extra gasoline expense that the steep inclines create. The road climbs up the Coquihalla pass, a mountain pass at an elevation of 1,244 m (4,081 ft) above the sea level.
Bob & Dawn Married 34 years
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