Are tunnels the answer to better urban transportation?
Monday, March 31, 2014, 12:20 PM
During the 1930’s and 40’s, with the number of vehicles exploding across North America, the answer to all of our roadway congestion problems was up in the air – trains and vehicles would be put up on elevated tracks and highways. The claim at the time was that these would instantly improve traffic flow without having to tear up entire neighbourhoods.
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It didn’t work. It ruined neighbourhoods, divided cities, created huge dead zones under and around them and certainly didn’t help with road congestion at all. At the time, given the available technology and political climate, elevated highways seemed like the best option. Unfortunately, elevated highways also require a great deal of maintenance and are no longer symbols of technological advance and mastery.
Urban planners have looked at underground tunnels for centuries as a solution to the need for safe, efficient travel – the main limitation has always been cost. Tunnels can be built to be safe, secure and move people and goods very efficiently, but until very recently they were incredibly expensive.
A century ago building a tunnel required an immense amount of physical labour, time and money. The original New York subway tunnels required 8,000 workers and over 60 people died in the project. The Holland tunnel had 66 deaths during construction, and 11 died in the construction of the Channel tunnel.
In the last few decades the advent of modern tunnel building machines has dropped the cost and risk significantly. In the last decade we have seen this technology advance to a point where tunnels can be built for less than twice the cost of an elevated roadway, while a British study has shown that costs are dropping around 4% every year. This is the result of technology becoming more mature, improved equipment, better designs, increased competition and refining the techniques used.
If you calculate the increased revenue by turning some of the above ground area into tax generating development (condos and retail) the cost is now much closer to regular above ground road construction costs. It also looks better, since new park land can be reclaimed, as well as adding bike routes and building neighbourhoods instead of destroying them.
Tunnels also have an additional benefit of not being affected by weather – snow, cold, rain, high winds, etc. – none of these environmental factors affect the drive in a tunnel.
Another interesting feature of tunnels is the ability to decrease vehicle emissions. The Laerdal tunnel in Norway pulls all of the exhaust from the tunnel through filters and cleaners that remove the dust, soot and even the nitrogen dioxide from the air. You can’t do this with an elevated road.
Every city is different and each have their own complexities with urban transportation. Tunnels are also not a ‘one size fits all’ solution, but given the advance of technology and increase in need, going underground is becoming a much more viable option.