mapj1:

Really if there is to be anything more than lip service to the environmental aspects, then there should be no longer be any  'if' in electrification, and overhead wires running an HV at 50Hz AC should be the preferred way of upgrading existing lines. Modern AC controls allow regeneration by inverter and transformers back into AC supplies, so the arguments that used to supported  using DC traction currents on the rails at a variety of voltages that date from the era of the mercury arc rectifier should now be retired. This reduces the number and complexity of feeder sub stations, and the risk to life, and potential for flooding problems  is far lower.

I'm not sure why it is so much more expensive in real terms to convert lines to electric than it was a few decades ago, I suspect creeping bureaucracy , the use of layers of subcontracting leading to a lack of economy of scale, rather than actual change to the technical issues of making holes in the ground and installing  gantries and insulators, though if others know better I'd be very interested. to know why.

There's this little thing called 'loading gauge' that tends to get in the way! (Or perhaps kinematic envelope might be better). Unfortunately, most of the UK rail network was built to quite reduced dimensions when compared with the Berne loading gauge used across much of europe or even the massive LGs in the US. Tight clearances mean any prospective upgrading to overhead HV would be accompanied with major bills for replacing overbridges or lowering track to accommodate the necessary clearances for the wires and all the associated disruption. I know of many incidences on the WCML where birds sheltering on the tops of wires under bridges have got too close to the structure and struck up an arc between the bridge and wire usually resulting in the burning through of the wire and more disruption to the network. Admittedly, there would be benefits in doing away with the third rail system, not the least being less risk of electrocution!


Regarding trolleybuses, why not bring them back? They are more flexible than trams, especially where sharing routes, infrastructure and vehicles are cheaper and cyclists don't have to contend with tracks in the road. Simples!

mapj1:

Really if there is to be anything more than lip service to the environmental aspects, then there should be no longer be any  'if' in electrification, and overhead wires running an HV at 50Hz AC should be the preferred way of upgrading existing lines. Modern AC controls allow regeneration by inverter and transformers back into AC supplies, so the arguments that used to supported  using DC traction currents on the rails at a variety of voltages that date from the era of the mercury arc rectifier should now be retired. This reduces the number and complexity of feeder sub stations, and the risk to life, and potential for flooding problems  is far lower.

I'm not sure why it is so much more expensive in real terms to convert lines to electric than it was a few decades ago, I suspect creeping bureaucracy , the use of layers of subcontracting leading to a lack of economy of scale, rather than actual change to the technical issues of making holes in the ground and installing  gantries and insulators, though if others know better I'd be very interested. to know why.

There's this little thing called 'loading gauge' that tends to get in the way! (Or perhaps kinematic envelope might be better). Unfortunately, most of the UK rail network was built to quite reduced dimensions when compared with the Berne loading gauge used across much of europe or even the massive LGs in the US. Tight clearances mean any prospective upgrading to overhead HV would be accompanied with major bills for replacing overbridges or lowering track to accommodate the necessary clearances for the wires and all the associated disruption. I know of many incidences on the WCML where birds sheltering on the tops of wires under bridges have got too close to the structure and struck up an arc between the bridge and wire usually resulting in the burning through of the wire and more disruption to the network. Admittedly, there would be benefits in doing away with the third rail system, not the least being less risk of electrocution!


Regarding trolleybuses, why not bring them back? They are more flexible than trams, especially where sharing routes, infrastructure and vehicles are cheaper and cyclists don't have to contend with tracks in the road. Simples!