A couple of them, including Maglev, had speedos in the passenger area. Unless it's lying, the trains maintained a solid 300km/h+ through the tunnels. TGV Lyria didn't have one so I'm not sure on that one.Legitimate question - why is HSR in tunnels speed-capped? I've ridden HSR in Japan, China, France, Switzerland and the trains travel at full speeds in the tunnels. What's different about here that means the trains can't travel full speed in tunnels unlike overseas?Never took your question as anything but geniune.
It would be faster to stay on the CCN than it would be to change to the metro. Would also be a lot more convenient.
Do you know 100% the train maintains its speed as because my experience this isn't easy to tell and I was using a GPS app. In Austria the train was doing 160km/h in the very Vienna tunnels then speeding up to 200km/h out of the tunnel and slowing for other tunnels. The Chunnel Tunnel is limited to 160km/h. T
The best I can find out is that it depends on the tunnel design, including length, longer and older tunnels tend to have lower speeds. he entrances and exits need special design as well.
My understanding why is that long tunnels have multiple issues for HSR is as follows
- Heat, as the train moves through the tunnel the air around the trains gets dragged along and therefore the cooling effect on the motors decreases
- Load/heat, as the train enters the tunnel it must now push alot of air and this created more wind resistance than outside the tunnel and as such the train either maynot have enough power or able to sustain the higher energy demands for extended periods of time again heat could be the limiting factor
- The piston effect caused by the train needs to be managed for the infrastructure and internal pathways in the tunnel. For example if the there was a station in the tunnel, the station would need full height platform screens or risk creating hurricane type conditions on the platform. Think about it, the train is approaching at 300km/h, there is some loss of pressure around teh train and assume ventilllation, but you are still going to have a +150km/h wind speed into the station. We know what happens in Sydney with the Metro and DD's being a snug fit in their respective tunnels and there are often crossovers.
- Issues mentioned above become more extreme when two trains are running towards each other.
- entering and existing the tunnel at high speed if not designed correctly needs careful planning or it creats a bomb or similar sound effect. Annoying for locals
The Otiro tunnel in NZ. Loaded coal trains face a 1:40 rise for 8km. To make this work there are doors placed at the top so that the train is pushing into the wind which then pushes air around the trains for both exhaust and managing the heat emissiions of the rear engines. I spoke with the driver there at Mt Aruthur station in 2009, he said the trains have two bank engines added to reduce risk of operation. basically keep the train moving at sufficent speed it gets enough air movement, reduce the heat output of the engines and traction motors and risk of engine failure. Otherwise 4 engines would be enough.
So I think yes these issues can be mitigated with larger bore tunnels and other fancy designs, all costing money but unlikely fully eliminated and hence I'm open to correction that there are not long HSR tunnels with trains travelling +200 - 250 km/h. Short distance probably no issue and the defintion of short distance may vary from location to location.
A couple of links I found
(I cannot open at work, so hopefully ok)
Overall my feeling on this is that HSR is a waste, but MSR is worth it.