Quote:
Originally Posted by lawfin
JUst out of curiosity what are the compartative cost say per mile for a 1. subway in a city in chicago, 2. an elevated line similiar to what we have 3. an elevated line that instead uses a monorail or other light rail solution, and 4. an at grade light rail solution
I you know please post with sources preferably
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Costs vary depending upon geographical conditions. As a general rule of thumb, light weight modern streetcars are the cheapest solution, just lay tracks in existing streets. Most streets have sufficient bases to carry their weight, so little street reconstruction is required. Next in line in costs, at more than twice streetcar costs, as a minimum, are rapid light rail trains. Since they are heavier, the streets will need stronger road beds to support the light rail trains, and much longer construction schedules including the street modifications, which is the main reason why they are more expensive. Light rail trains are very flexible, capable of street running, elevated above and depressed under. Elevated is twice as expensive as running at grade. Subways are twice as expensive as elevated tracks.
Modern elevated monorails and elevated light rail trains have approximately the same capital costs. Monorail switches (turnouts) are much larger in size that conventional rail base turnouts, which is their main disadvantage. Monorail cars are usually smaller in size than light rail cars, and carry less passengers. Monorails are very popular with the public until they see the huge stations 30 feet above city streets. The public dreams a Disneyland experience, but forget Disney places stations within buildings. The monorail station is usually contained within a building's lobby. It works at Disney because the buildings and monorail were designed and built at the same time, which an existing city can't do everywhere along the line.
All elevated tracks block sunlight, it doesn't matter if it's light rail or monorail, which is another sore point with the public. Grade separate tracks should only be considered in very dense areas with high traffic congestion. Once the tracks leave downtown and uptown areas, it's far cheaper to build the rest of the line at grade. Monorails must always be grade separated. Another advantage for light rail trains, which aren't limited.
The cheapest solution by far is commuter rail, which you forgot to list. Using the existing freight railroad right of ways really saves a whole lot of capital.