5 ms·

Of anyone wants to see what hunting looks like, then watch a video of the London DLR. The DLR has very tight corners, and was originally built on very tight bu

Of anyone wants to see what hunting looks like, then watch a video of the London DLR. The DLR has very tight corners, and was originally built on very tight budget. As a result it uses very steeply bevelled wheels to handle the corners. The wheels do a great job on the corners, but on the straight they suffer from significant hunting, resulting in the trains wobbling side-to-side (and slightly up-and-down), at a rather alarming frequency and amplitude. Not quite enough to make you sea sick, but it’s pretty close.

dredmorbius 4y ago
The DLR is a low-speed network with tight turning radii. I haven't found any footage clearly showing hunting (in part because it's difficult to distinguish other lateral-movement-inducing elements such as turns and switches), but the basic operating parameters are fairly clear. I suspect the wheels have high conicity. The rolling stock is also likely lighter than a heavy-rail system. https://yewtu.be/watch?v=i1pAfKsL1bk https://yewtu.be/watch?v=i1pAfKsL1bk
- cstross 4y ago
  Well, there's a reason they named it the Docklands Light Railway! (Large stretches of the original network built in the 1980s ran on elevated track, supported on pylons over ground that's a mixture of chalk and clay and tends to waterlog. Heavy rail can be built over and under that part of the Thames, but it has its own special challenges and the DLR was built as the cheapest way of getting commuters in and out of the Canary Wharf office towers, from Tower Gateway and the actual London Underground network to the west. Then from the 1990s onwards mission creep set in ...)
  - dredmorbius 4y ago
    Ha! Absoltuely correct and I'm honoured to be Strossed. Thanks for the, er, bedrock explanation as well.
  - ClumsyPilot 4y ago
    its like the lifeline of east london, and it connected large aread of land that used to be borderline slums. Now there are highriae apartments and the fact that they have access to piblic trandport has increased their valuation by billions.
    - dredmorbius 4y ago
      Providing improved transport and transit is amongst the best way of increasing property values. A stellar example is Denver, Colorado, which grew in size tenfold in a decade after a branch line connected it to the Transcontinental Railroad in 1870, becoming the dominant Rocky Mountain region city, a title which might otherwise have gone to Chyenne, Wyoming. It's also something of a two-edged sword: the property value boost makes further transit rights of way far more expensive to acquire. I've noticed in particular that much rail development happens either as greenfield projects within countries as they're first industrialising (UK and US in the 19th century, China in the late 20th), or following a devastating war or other economic setback --- Japan's shinkansen and to a somewhat lesser degree France's TGV are both legacies of WWII. In the US, aside from political opposition from other parts of the transportation sector, it's wealthy landowners who are the most significant obstacle to new development.
- avianlyric 4y ago
  Oh trust me, the hunting on the DLR is pretty bad. You’ll notice the second the trains get up any speed on a straight. The problem is bad enough for it appear in its own section of the DLR Rolling stock wiki page. https://en.m.wikipedia.org/wiki/Docklands_Light_Railway_rolling_stock#Problems_Experianced https://en.m.wikipedia.org/wiki/Docklands_Light_Railway_roll... Here’s good video about the DLR time stamped to point that demonstrates the hunting well. https://youtu.be/_WosYRVYMEM?t=907 https://youtu.be/_WosYRVYMEM?t=907
  - dredmorbius 4y ago
    Thanks. The video confirms what I'd surmised: that tight turns were the reason for more conical wheels. The sections I watched didn't actually show the wheel geometry, though, and I've not been able to find any photos online (DDG and Google Image search, various combinations of "DLR | Docklands Light Railroad | (conical|cone|conicity) wheel"). The WIkipeidia DLR Rolling Stock article mentions the conicity and hunting issues, but doesn't show the wheels either: https://en.wikipedia.org/wiki/Docklands_Light_Railway_rolling_stock#Problems_Experianced https://en.wikipedia.org/wiki/Docklands_Light_Railway_rollin...

dredmorbius 4y ago

The DLR is a low-speed network with tight turning radii. I haven't found any footage clearly showing hunting (in part because it's difficult to distinguish other lateral-movement-inducing elements such as turns and switches), but the basic operating parameters are fairly clear. I suspect the wheels have high conicity. The rolling stock is also likely lighter than a heavy-rail system. https://yewtu.be/watch?v=i1pAfKsL1bk https://yewtu.be/watch?v=i1pAfKsL1bk

cstross 4y ago
Well, there's a reason they named it the Docklands Light Railway! (Large stretches of the original network built in the 1980s ran on elevated track, supported on pylons over ground that's a mixture of chalk and clay and tends to waterlog. Heavy rail can be built over and under that part of the Thames, but it has its own special challenges and the DLR was built as the cheapest way of getting commuters in and out of the Canary Wharf office towers, from Tower Gateway and the actual London Underground network to the west. Then from the 1990s onwards mission creep set in ...)
- dredmorbius 4y ago
  Ha! Absoltuely correct and I'm honoured to be Strossed. Thanks for the, er, bedrock explanation as well.
- ClumsyPilot 4y ago
  its like the lifeline of east london, and it connected large aread of land that used to be borderline slums. Now there are highriae apartments and the fact that they have access to piblic trandport has increased their valuation by billions.
  - dredmorbius 4y ago
    Providing improved transport and transit is amongst the best way of increasing property values. A stellar example is Denver, Colorado, which grew in size tenfold in a decade after a branch line connected it to the Transcontinental Railroad in 1870, becoming the dominant Rocky Mountain region city, a title which might otherwise have gone to Chyenne, Wyoming. It's also something of a two-edged sword: the property value boost makes further transit rights of way far more expensive to acquire. I've noticed in particular that much rail development happens either as greenfield projects within countries as they're first industrialising (UK and US in the 19th century, China in the late 20th), or following a devastating war or other economic setback --- Japan's shinkansen and to a somewhat lesser degree France's TGV are both legacies of WWII. In the US, aside from political opposition from other parts of the transportation sector, it's wealthy landowners who are the most significant obstacle to new development.
avianlyric 4y ago
Oh trust me, the hunting on the DLR is pretty bad. You’ll notice the second the trains get up any speed on a straight. The problem is bad enough for it appear in its own section of the DLR Rolling stock wiki page. https://en.m.wikipedia.org/wiki/Docklands_Light_Railway_rolling_stock#Problems_Experianced https://en.m.wikipedia.org/wiki/Docklands_Light_Railway_roll... Here’s good video about the DLR time stamped to point that demonstrates the hunting well. https://youtu.be/_WosYRVYMEM?t=907 https://youtu.be/_WosYRVYMEM?t=907
- dredmorbius 4y ago
  Thanks. The video confirms what I'd surmised: that tight turns were the reason for more conical wheels. The sections I watched didn't actually show the wheel geometry, though, and I've not been able to find any photos online (DDG and Google Image search, various combinations of "DLR | Docklands Light Railroad | (conical|cone|conicity) wheel"). The WIkipeidia DLR Rolling Stock article mentions the conicity and hunting issues, but doesn't show the wheels either: https://en.wikipedia.org/wiki/Docklands_Light_Railway_rolling_stock#Problems_Experianced https://en.wikipedia.org/wiki/Docklands_Light_Railway_rollin...