Masts for 25kV Overhead Wires.
 

In Staff2600's great pic of "Tangmere" there is a latticework overhead gantry mast. I know that this design of mast is not new but they do appear to be getting more and more common on the West Coast Main Line. Does anyone know the reason for their increased useage. Can they really be cheaper than 2 separate masts or is there a more technical reason?

John.

With my (non-rail) civil-engineer hat on. The benefit of only having a single foundation for the gantry is that you dont have the problem of getting the distance exactly right between two foundations on either side of the track. Or, you have to make every gantry unique to span the varying distance across the tracks.

Or you have to put up separate single pylons for every track with all that extra digging and moving cables and drains out of the way

Also - foundations are expensive, but the extra steel work is relatively cheap. So while you may not save on cost overall, it may not be that much more expensive.

Just a guess.

Thanks for your ideas Shedcat:)
I wouldn't mind betting that cost as opposed to technical requirement comes into it somewhere;)
These single foundation structures always look "top heavy" to me:)
John.

You are right, they are top heavy and inefficient. So, for someone to decide that building them that way is the cheapest solution, there must be a different more critical problem they are trying to overcome. I can only think foundations, or possibly the hassle of trying to obtain Posessions on two tracks is so bad, that it is better to build from one side only.

You ask a simple question and before you know it - I need a science degree!!