Alternative for a north south spine for road to rail shift

[DownSouth]

Freight can be quite costly to the railway

Excuse me? Isn't shifting large amounts of stuff from one place to another exactly what railways are for?

Fast, frequent freight is easily possible, and has effectively been done in Britain several time, the GC 'Windcutters', 'Green Arrow', the 'Condor' and so on, even RES might count. The question is whether something with the weight of a large container can be moved at the same speed as a MkII (hauled by a 90 or a 57 perhaps) without doing serious damage to the track. I'm not quite sure about the route availability and axle loading, but it's got to be higher than a MkII.

The best example of higher-speed freight in the world would have to be the Super C which ran at an average of 63.7mph even on the American system which is largely centred around heavy trains rather than fast ones. Mail doesn't count!

Out of all the different types of cargo transported on rail, the majority of intermodal containers are among the lightest. Containerised tanks and bulk freight containers are obviously heavier, but they could still travel at standard freight speeds while lighter intermodal trains could go faster, even up to 100mph on the best mainlines and at night on high speed lines.


Perhaps looking at some of the maths could help with understanding things...

• The Super Voyager is a 125mph passenger train, and the empty weight per carriage is about 56t (based on 282.8t for a five car set) which works out to an axle load of 14t even before you add passengers and their luggage. Higher speed freight won't be going as fast as that (100mph at the absolute most) for a whole bunch of reasons including the fact that locomotives have axle loads right up to 22t in Britain. Therefore using the Super Voyager's mass and axle load as the basis of a few quick sums should leave us with a fair amount of headroom.

• Freightliner's website shows most of their intermodal wagons as having tare weights between 17t and 20t, only the KTA well car being heavier at 23t. If we take 20t as the tare weight for this proposed higher-speed intermodal freight, that leaves you with room to carry up to 36t of cargo on top. A design standards paper from Australia (more on that below) also refers to double-stack well wagons with tare weights of 20t.

• The first reliable data I've come across on the web about the weight of intermodal containers is a design standards paper for the proposed inland freight corridor in Australia. This states that the average intermodal container weight is 10t per TEU (twenty foot equivalent unit). It's reasonable to assume this is roughly the same across the world.

• Freightliner's website indicates that 45ft containers are the longest used in Britain, so the average weight would be about 22.5t according to the average weight of 10t/TEU. However, the maximum weight we found from the Super Voyager axle load and the Freightliner wagons was 36t, which is 160% of that assumed average weight for a 45ft container.

• This might exclude the heaviest 40/45ft containers and containerised bulk freight, but they could still run at current speeds.

• With this much room to play with on the wagon/container side of things, the question of how to run higher-speed intermodal freight is really more about what would be needed to haul them. Multiple four axle electric locomotives (distributed traction using Locotrol maybe?) could work well, perhaps an AC version of the TRAXX F160 used by Trenitalia for 160 km/h (100mph) freight and scaled down to British gauge could be what is needed.


The biggest benefits of higher speed freight would obviously be that it could mix in with passenger traffic on the classic lines better, it could use the high speed lines more effectively at night when passenger trains aren't running (linking directly to Europe) and make for better competition on time-sensitive freight.

 

[GearJammer]

I can't see a freight multiple unit working either, how would it work? I Can't see distributed power working or lasting long, have you seen a 25 tonne container being put on a wagon? I don't think any traction equipment would withstand the abuse, take a standard 60ft freightliner flat.... it would have say 60tonne of container on it, plus to withstand the strain and abuse of loading you'd need a heafty wagon which would be heavy, plus then the weight of traction motors etc, it would be way to heavy.

 

[HSTEd]

I can't see a freight multiple unit working either, how would it work? I Can't see distributed power working or lasting long, have you seen a 25 tonne container being put on a wagon? I don't think any traction equipment would withstand the abuse, take a standard 60ft freightliner flat.... it would have say 60tonne of container on it, plus to withstand the strain and abuse of loading you'd need a heafty wagon which would be heavy, plus then the weight of traction motors etc, it would be way to heavy.

Traction motors are extremely tough, the newest are designed to be treated as sealed units with no maintenance potentially for months or years at a time and are extremely light (we are now down to ~1kW/kg for the latest PMMs from the AGV) and if we aim a power to weight ratio of say 7hp per tonne (similar to a Ckass 315 which would be at the low end of performance for a suburban multiple unit) we get:

The base vehicle for this comparison will be 13.8t tare weight 48ft long articulated spine car units (reference).

The maximum load of each unit in said five container formation comes out at a total of 37.6t, with an axle load of 18.8t (which is high but not catastrophically so I think). This would require a power output of roughly 263hp per bogie, which could be provided by traction motors weighing approximately 200kg in total, which is considerably lighter than the AGV bogies and is pretty much negligible compared to the weight of the vehicle. ANd since each five carriage formation only has ~1300hp it can have a suprisingly small traction transformer and traction electronics package which again has negligible mass.

If we want a lower axle weight to permit higher speeds (the average Eurostar axle weight comes out at 16.2t which is not that much lower) you can not use articulated spine cars and use more traditional bogie flats.