Thanks for previous comments.
I do think that there may be ways round some or even all the points made (at a cost).
Mast base in 6 foot - low height steel base with 4 claw feet to bridge drains?
How much clearance is there between two passing trains in the six foot and what structures are currently allowable in the six foot and to what height?
Stress - a taller mast (where possible) with bracing to 'arms' . Similar to some old tram designs but of greater weight and capability. The 'arms' could be to be longer to cater for going round curves.
I suppose that conventional masts could be used in 'non-scenic' or difficult locations, but an improved design would surely make for passenger satisfaction on scenic lines if it is possible.
On a related subject,
I am aware that mast structures generally sit on 4 bolts whether metal piled or concrete based, presumably to aid alignment. Although large, these bolts seem to an outsider to be rather a weak point when compared to the size and weight of the mast they are supporting above. Are these bolts the optimum size, a weak point or are the masts themselves perhaps a little over-engineered?
The distance between stock passing obviously varies depending on the width of the stock and track geometry, but a good but rough guide is 450mm/18" based on vehicle width and no lateral deflection.
The name "six foot" is something of a misnomer though - not all tracks are six feet apart, some are more, some are less, though not much less, as you then start getting into the realms of vehicles not being allowed to pass in certain locations.
You can quickly see that a mast that's 250mm wide leaves just 100mm of space on either side, and you wouldn't be able to attach any components below cant rail height on the mast, such as return wires or ATF wires, and you really need to be allowing more than 100mm of lateral movement, so you've got masts that are really within the dynamic envelope of most common rolling stock types.
It's also worth remembering that all of this is based on straight, level track with no cant. If you have track that has a cant, you need your electrification mast to be installed at a jaunty angle, it can't be vertically square as it's going to then be well within the dynamic envelope on one of the lines. OLE components aren't designed for installation at a jaunty angle. They go on vertically square or near square masts.
Fitting expensive, specially manufactured components around drains is a recipe for disaster - don't interfere with drainage, as it upsets many people, starting with the passengers when the route is closed due to flooding and ending with the route director when he finds out what blocked the drain. Your mast and overhead catenary deflects in wind, that causes the base of move or vibrate, which can damage your drain. Leave well alone.
Not sure what the bracing arms concept is, it sounds terribly like a back to back twin track cantilever structure, which is going to be too wide to fit into the six foot from the start. It's also going to be a bit uglier and more prominent than a pair of simple, unobtrusive masts on either side of the track, cess mounted.
The Swiss don't seem to have a problem with the Glacier Express being ruined by decades old OLE masts, they have a staggeringly beautiful country which isn't impacted by their total electrification.
The only suggestion I've got for electrification of a route such as the S&C, is that the conventional masts be manufactured from COR-TEN weathering steel rather than hot dipped galvanised steel, so it should settle into the natural landscape a bit more readily, but I see absolutely no reason nor no justification for highly bespoke equipment that's already been very carefully designed by the very people who have so diligently covered Switzerland with OLE catenary.
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Don't think there would be enough room
As an aside, I think they should design specific stanchions for scenic areas.
Take Bath, I believe they're looking how to electrify sympathetically, hope fullywith a design that resembles street lights or something.
Bath gets bespoke masts with conventional Series 1 single insulator cantilevers, as per this NR/F+F image.
