Worst Junction?

[Tom]

Yorkie, come back to me after you do that junction at least twice a week standing up on a crowded packed train and you almost fall over.

 

[Donny Dave]

This is going to be contraversial, but.....

Wrawby Jn has to be one of the worst junctions. Even at 15mph, you still get bounced around a lot....

 

[Broken Viking]

Hi everyone!

Wrawby Jn has to be one of the worst junctions. Even at 15mph, you still get bounced around a lot...

Dare I suggest going past Platform XIII at Clapham Jct at 125mph? :eek:
It's never been done for a very good reason...Even on board an APT at full-tilt (And with the platform cut back a bit to prevent the train hitting it!) it would prove to be a very interesting experience to say the least! :toothy10:

On the subject of air-ride suspension though: I believe that the 700 Series Shinkansen (Japanese bullet train) tilts up to 5° by adjusting the air pressure in the suspension "bubbles" (I.E: There's no actual "tilting" equipment such as that found in the APT or Pendolino)...Does anyone reckon that this feature could be safely added to the Desiro, Sprinter and HST fleets to up the top-end around bends a bit?

Disastros...

ROTFLMFAO!!!

Farewell...
>> Death <<

 

[yorkie]

Yorkie, come back to me after you do that junction at least twice a week standing up on a crowded packed train and you almost fall over.

I've done it, and I won't change my mind that there's no reason why the junction cannot be smooth. The fact that it isn't is probably down to the type of points in use. There appears to be space for more suitable crossovers!

 

[Tom]

What's a more suitable crossover than a Y point which allows the speed that is currently "got"?

 

[Donny Dave]

How about something like Colton Junction. 125mph for both routes....

 

[Kris]

I've done it, and I won't change my mind that there's no reason why the junction cannot be smooth. The fact that it isn't is probably down to the type of points in use. There appears to be space for more suitable crossovers!

I must admit - I thought that you were shot away at first (my aplologies) - it's certainly not a straight piece of track but I think I can see where you are coming from.

If one was to go just 500 yards (or metres in foreign) further - there could have been high speeds points built on the straight section just past where the existing Y points are.

A much smoother connection.

 

[Jordy]

This is going to be contraversial, but.....

Wrawby Jn has to be one of the worst junctions. Even at 15mph, you still get bounced around a lot....

Wrawby is a bit bouncy nowadays, but have you been over Brocklesby recently, Westbound is very, very bumpy hock:

 

[Donny Dave]

Wrawby is a bit bouncy nowadays, but have you been over Brocklesby recently, Westbound is very, very bumpy hock:

Why would I need (or want) to go that far east on a train? It's a bit grim that way....

 

[O L Leigh]

On the subject of air-ride suspension though: I believe that the 700 Series Shinkansen (Japanese bullet train) tilts up to 5° by adjusting the air pressure in the suspension "bubbles" (I.E: There's no actual "tilting" equipment such as that found in the APT or Pendolino)...Does anyone reckon that this feature could be safely added to the Desiro, Sprinter and HST fleets to up the top-end around bends a bit?

They already do to a certain extent by means of the "fat b@stard valve", but only to maintain the vehicle on the level. To make them tilt would require a completely new air suspension system. Besides, none of these trains were built with a tilt profile which would mean that they would strike every bridge and platform edge along the route when being caned.

As it works at the moment, there is an FBV on each airbag which is operated by a rod that is mounted with one end on the bogie and the other on the vehicle body. When the vehicle is heavy, the rod pushes up to allow more air into the bag. Too light and the rod drops and vents air out. That way, each vehicle is kept level and at a pre-set height. Around corners (assuming that the track is perfectly smooth), the bags on the offside of the vehicle would be inflated to a higher pressure than those on the nearside to counteract the natural tendency for the vehicles to roll to the offside of any bend. Unfortunately the system makes heavy use of the air supply, which in turn puts quite a bit of strain on the compressor. Every time the system vents air and then needs to replace it, the compressor would need to run to keep the Main Res Pipe at the required pressure.

However, the current system would not allow for tilting because the airbags are not sufficiently flexible to allow them to inflate to the point where they would tilt the vehicle. In fact, rail vehicles do not sit on their airbags as if on a cushion of air, as each one contains a coil spring that supports the vehicle weight and acts as a back-up should the air suspension fail or an airbag burst. Even if they were, the fixed rod control system would need to be done away with and replaced with something more sophisticated that could detect when the train was cornering and would know when and how to intervene to create a tilt.

In addition to all this, you would need to ensure that the track is perfectly smooth. As good as the current air suspension systems are on our trains, they can be severely undone by a bumpy or uneven piece of track because they can't react fast enough. You can hear the system trying to compensate for bumps and body roll on sections of track like the "Up Suburban" line at Liv St, where units bounce up and down at moderately slow speeds. When each vehicle reaches the top of the bounce you can hear a momentary hiss as air escapes through the FBV, but then the vehicle crashes down on it's bumpstops because there is insufficient air to prevent it from doing so. Then it bounces up again and yet more air is lost through the FBV making the next landing that much harder, and so on until the train reaches a flatter section of track.

The Shikansen idea does sound interesting. However, I would need to know more about how it works to say whether or not it could be implemented here. The thing is that you would have to make sure that any system along these lines worked while still ensuring that an adequate ride quality was maintained. Given the lumpiness of our permanent way and that current air suspension systems are one of the main means of shock absorption on UK passenger rail vehicles (compare the ride quality of a Pacer with a Cl150 Sprinter), raising the pressures of the offside airbags to the point at which they could lift the vehicle far enough to generate 5 degrees of tilt is going to have a negative impact on ride quality. You've also got to look at whether or not vehicles using this system would need lower rooflines to ensure that they stayed within the UK loading gauge when tilted. If you raise one side of a vehicle without lowering the other, it will be taller overall than it is when it isn't tilted.

However, the short answer has to be "no".

**EDIT**

In terms of which junction is the worst, it would be hard to judge. Traverse one on a train that rides it well and you might think that you've got a good 'un. Ride it again on a knackered old unit that is overdue it's next exam or has badly adjusted suspension and you might disagree.

From experience, I have to say that combination high speed/low speed junctions are the worst. We've a few that are 60-85mph in one direction and 10-30mph in the other. Where both routes are curved in opposite directions you have to allow for changes in cant. For the lower speed route you would want the junction relatively flat, but the higher speed route demands a certain amount of cant. Consequently, you get junctions where trains on the faster route experience bad sway because they are going from a section of line with an appropriate amount of cant to a section of line that is totally flat and back to a section of line with an appropriate amount of cant within a short space of time.

one TN

 

[Daniel]

After riding over it in both a Meridian and a HST cab, i'd say Trent Junction is a pretty good contender for worst junction...

Just by looking at the tracks you can see that they "wobble"... there's a perminant "T"SR on it, with an AWS buzzer, I believe it's 50MPH for passenger trains.