Discover and read the best of Twitter Threads about #RailwaysExplained
Most recents (7)
Clamp, link, pulley: the 3 headspan genders (a #railwaysExplained thread)
A few of the #OLEbook images are a bit meh. So yesterday I went out on a trip to West Ealing to pick up some better ones. In this case, headspan supports.
But 1st, a refresher on along-track movement
1/
A few of the #OLEbook images are a bit meh. So yesterday I went out on a trip to West Ealing to pick up some better ones. In this case, headspan supports.
But 1st, a refresher on along-track movement
1/
All OLE systems have to deal with the phenomenon of along-track movement - the amount of expansion and contraction the wires experience as wire temperature varies, due to ambient heating/cooling from solar gain and wind, and also current heating due to electrical load
2/
2/
All modern mainline systems deal with this by using auto-tensioning; a device is provided at each end of the wire which provides a constant tension. Weights or springs are used, & the wires are able to expand / contract around a fixed central point - the midpoint anchor (MPA)
3/
3/
In last night's #RailNatter, we talked about #BlackLivesMatter and how it is crucial to keep up the pressure and for all of us to learn about our colonial past.
Here's a really important #RailwaysExplained about how Britain's railways only really exist as a legacy of slavery…
Here's a really important #RailwaysExplained about how Britain's railways only really exist as a legacy of slavery…
Back in 1833, the UK government abolished slavery and decided to compensate former slave owners - not the people who had been held as slaves - to the tune of £20m…
That's more than £19bn in today's money, and represented 40% of the government's budget at the time.
That's more than £19bn in today's money, and represented 40% of the government's budget at the time.
Around half the money stayed in the UK despite only 3000 of the 47000 compensated slave owners living here, meaning that very wealthy individuals received huge payouts.
People like George Hibbert and John Gladstone received the 1833 equivalent of tens of millions of pounds each.
People like George Hibbert and John Gladstone received the 1833 equivalent of tens of millions of pounds each.
THREAD: A few of you requested a #railwaysExplained thread Return Conductors (RCs) and Auto Transformer Feeders (ATFs). As part of that I'll be attempting to explain how immunisation works. HEALTH WARNING: this will involve electromagnetism. Apologies in advance!
1/
1/
Lets start with the very basics: overhead line forms part of an electrical circuit. Just like all circuits, the electricity flows out from a supply (the feeder station) to the load (the train) and then flows back to the supply. The OLE forms the outward leg of the circuit
2/
2/
The simplest way to form the return half of the circuit is simply to use the running rails. Connect the non-OLE side of the train motor to the wheels, current flows through the wheels and into the rail, then back to the feeder station.
3/
3/
High Speed 2 won't actually be the UK's second modern high speed railway, just as HS1 wasn't its first... This title should go to another line which opened in 1983 (only two years after France's LGV Sud-Est).
Time for a #RailwaysExplained thread on the SELBY DIVERSION 🚆
Time for a #RailwaysExplained thread on the SELBY DIVERSION 🚆
Back in the mid-1970s, British Rail was making journeys faster with the introduction of its "Inter-City 125" high speed train, and was busy upgrading and realigning the ECML for 200km/h.
They were already running the 2nd fastest timetable in the world with '125s on the GWML.
They were already running the 2nd fastest timetable in the world with '125s on the GWML.
The only high speed line in the world was Japan's Tōkaidō Shinkansen which had opened in 1964... This railway was designed for 250km/h and didn't get above 210km/h in normal operation.
France were the next furthest forwards, with contracts being let for the 300km/h LGV Sud-Est.
France were the next furthest forwards, with contracts being let for the 300km/h LGV Sud-Est.
These long train noses are because of civil engineering short-sightedness, ironically enough... #RailwaysExplained
The only reason they are this shape is to reduce the sonic boom resulting from tunnels that are too narrow and have too tight a portal 🚇💥
The only reason they are this shape is to reduce the sonic boom resulting from tunnels that are too narrow and have too tight a portal 🚇💥
How does this happen? #RailwaysExplained
As the train enters the tunnel, it creates a pressure wave. This pressure wave reflects off the mass of air at the other end of the tunnel and then hits the train (which is still travelling through the tunnel) at the speed of sound. Boom!
As the train enters the tunnel, it creates a pressure wave. This pressure wave reflects off the mass of air at the other end of the tunnel and then hits the train (which is still travelling through the tunnel) at the speed of sound. Boom!
This isn't just a noisy nuisance... The sonic boom can injure passengers and staff, as well as damaging the train and tunnel structure. #RailwaysExplained
There are three options to avoid this:
🎯 bigger tunnels
🕳️ better portals
🚅 silly train noses
There are three options to avoid this:
🎯 bigger tunnels
🕳️ better portals
🚅 silly train noses
THREAD: some of you might be wondering what the hell this train is. I'll try to explain that, while touching on some of the wider requirements for testing new #OLE for entry into service #railwaysExplained
1/
1/
This is an OLE test train that's been put together by the @networkrailwest electrification project team. The train is intended to undertake mechanical and electrical testing of the OLE between Bristol and Cardiff in advance of entry into service
2/
2/
The mechanical testing is performed using the pantograph on top of the class 90. It is unusual in two ways: 1) it carries force & acceleration sensors so that it can measure contact force, and 2) it is the only cl 90 carrying an HS-X pan, the type used by @GWRHelp at 125mph
3/
3/
Annoyingly, this thread about US track gauge has gone viral. It is also entirely bollocks (other than US standard gauge being 1435mm).
Time for a quick thread... #RailwaysExplained
Time for a quick thread... #RailwaysExplained
As the railways expanded across the US, several different track gauges became predominant, just as was the case in Europe (nope - the Romans nor horses bottoms had anything to do with track gauge)... #RailwaysExplained
By the 1860s, there were thousands of miles of track with gauges that didn't conform to Stephenson's original 4'8.5" - in fact only around half of the railways in the US used this gauge.
Then the civil war happened (no, not that one)... #RailwaysExplained
Then the civil war happened (no, not that one)... #RailwaysExplained
