Adding Rubber-Tyred Metros to Motorways
Rubber tyred trains could run down the centre of existing motorway easements as they can handle gradients up to 13%. (Image: Lyon Metro, Wikipedia) |
Some of the best easements for public transport are down the middle of existing motorway-grade roads. However, gradients on these roads make the placement of conventional rail lines on the centre of motorways difficult or impossible.
For example, the Burnley Tunnel on Melbourne's City Link motorway has grades of up to 6.2%. The maximum grade for steel rail track is around 3%.
Rubber Tyred Metros offer a way around this as they are able to cope with grades of up to 13% - easily enough for any existing motorway grade in Australia.
The other option is a monorail but RTM's are likely to be significantly cheaper if their is the grade-separated space to put them at ground level.
Space for a Rubber-tyred Metro system? (M1 Motorway, East Malvern, Melbourne.) |
Advantages of Rubber Tyred Metros
- The ability to climb or descend the gradients that exist on motorways. RTMs can cope with gradients up to 13%. At such gradient conventional rail tracks would be likely to need a rack & pinion system.
- Smooth ride.
- Faster acceleration.
- Short breaking distance, allowing more frequent services.
- Quiet operation of trains for residents.
- Fully independent of existing rail systems.
Disadvantages of Rubber Tyred Metros
- Higher energy consumption than steel rail systems - but steel rail systems cannot handle the gradients.
- More heat is generated - but these trains would mostly operate in the open air so not a major issue.
- Loss of traction in snow and ice - may be an issue in Hobart but not elsewhere in Australia. Services may be slowed down during occasional massive hail storms.
- Tyre replacement costs - this needs to be quantified to ensure it is manageable. Tyres need to be recycled responsibly.
- Existing RTM systems seem to be be limited to 80km/h. However, this is probably due to the station intervals rather than fundamental issues with the technology.
Types of Rubber-Tyred Metro
Central Guide Rail
Central rail-guided rubber-tired rolling stock operated by Sapporo City Transportation Bureau, Japan, and built by Kawasaki Heavy Industries. (Image: Sapporo Metro, Wikipedia) |
Switches operate like monorail beam switches.
Edge Guide Rails
Edge guide rail system on the Montreal system. (Image: Montreal Metro, Wikipedia) |
Switches use conventional points on the standard gauge track to guide trains. Rubber tires keep supporting the full weight of the trains as they go through switches. Guideways are provided in order to ensure there are no gaps in the electrical power supply.
The Montreal metro is fully underground which avoids problems that an RTM system like this would have with snow and ice.
Rubber-tyred metro
See Wikipedia article on this form of transport.