Split speed restrictions.

[LNERGE]

My signalling simulation for Ely North Junction is undergoing a few changes one of which is to lengthen the time certain classes of trains are in section. On the Lynn road the bridges over the Wissey and Ouse had a 20/40 speed restriction. I intend to alter things so classes 6,7,8 and 9 take six minutes longer to pass through the Downham - Littleport section. Would it be classes 1 and 2 that could obey the higher limit or would 3, 4, 5 and 0 be allowed to take the higher limit too?

[Edwin_m]

Current rule book states:

 

The bottom figure always shows the higher speed. It applies to:

• passenger trains (loaded or empty)

• parcels and postal trains (loaded or empty)

• light locomotives.

The top figure applies to all other trains.

 

This may have been different in the past - I've an idea anything conveying four-wheelers had to keep to the lesser speed.

[phil-b259]

My signalling simulation for Ely North Junction is undergoing a few changes one of which is to lengthen the time certain classes of trains are in section. On the Lynn road the bridges over the Wissey and Ouse had a 20/40 speed restriction. I intend to alter things so classes 6,7,8 and 9 take six minutes longer to pass through the Downham - Littleport section. Would it be classes 1 and 2 that could obey the higher limit or would 3, 4, 5 and 0 be allowed to take the higher limit too?

 

Today, most split speed restrictions are not to do with the class of train as such, the actual motive power being the overiding factor. In general, because they are lighter, unit trains (DMUs / EMUs) are allowed to travel at a higher speed than locos. As for things like the HST - it is a bit of a grey area as to what they fall into as in some cases they are treated as unit trains in other cases not because the power cars are quite heavy. Voyagers, Adalantes and Pendalinos are IIRC deffinatley treated as unit stock though.

[LNERGE]

The simulation is set in the early 80's with most Lynn passenger trains 37 hauled. Later they went over to 47's but they were still allowed over the two structures at a higher speed than a 47 hauled freight.

[The Stationmaster]

I suggest starting here for information on differential speed restrictions although it is slightly out of date http://www.rgsonline.co.uk/Railway_Group_Standards/Control%20Command%20and%20Signalling/Railway%20Group%20Standards/GKRT0038%20Iss%202.pdf

 

N.B. They are 'differential restrictions' not 'split restrictions' (or are you asking about split restrictions (which I think are long banned as confusing).

 

Seeing taht you are talking about freight there could well have been a restriction shown on a BR 29973 form and that won't be published anywhere publicly accessible as far as I know. The simplest answer is to look at teh WTT if you can get hold of one (or if the route still has the relevant freight trains the WTT is of course on the internet).

[royaloak]

Dont confuse split speed restrictions with EPS/ MU signs.

 

185s and voyagers are NOT classed as MUs (because of the ridiculous heavy axle load) and must stick to the lower speed on MU restrictions.

[phil-b259]

Dont confuse split speed restrictions with EPS/ MU signs.

 

Guilty as charged

 

185s and voyagers are NOT classed as MUs (because of the ridiculous heavy axle load) and must stick to the lower speed on MU restrictions.

 

A good surgestion for a quiz queston there (when is a MU not a MU).

Are HSTs classed as MUs then?

[LNERGE]

N.B. They are 'differential restrictions' not 'split restrictions' (or are you asking about split restrictions (which I think are long banned as confusing).

 

I can remember the cut out speed sign showing both 20 and 40 but i can't recall which was on top. I'd say the restriction was in place from around 1978 to about when the line was electrified. I don't know why the structures had this speed restriction but i do remember the pile of COVHOPs and the bottom of the embankment that may have had something to do with it.

 

Edit.. One of the structures in question..

 

http://www.geograph.org.uk/photo/577756

[royaloak]

Are HSTs classed as MUs then?

Not sure, I dont drive them.

 

How is that for being diplomatic!

[The Stationmaster]

 

Are HSTs classed as MUs then?

For differential speed restrictions they are classed as passenger trains UNLESS there is a differential speed for HSTs - in which case they are classed as HSTs.

[TheSignalEngineer]

The latest issue of The Rule Book gives this explanaton of the letters on Permissible Speed signs:-

HST - class 91 locomotive with mark 4 vehicles and DVT,

168/170/171/175/180/220/221/222/253/254/373/390

 

MU - multiple unit trains

DMU - diesel multiple units

EMU - electric multiple units

SP - class 150/153/155/156/158/159/165/166/168/170/171

CS - class 67 locomotive

 

At locations where both HST and SP speeds apply, classes

168/170/171 may run at the higher of the two speeds.

Class 185 trains must not run at any MU or DMU speeds.

[big jim]

just to throw a slight spanner in the works regards the speeds signalEngineer has posted there are also local instructions regarding different types of traction for different locations

 

also worth noting that class 172 aren't in the above list (instructions will be in the won/pon until added to the rulebook), handliy the 172 is also a prime example of a "spanner in the works".

 

172 are capable of 100mph and take the HST speeds where applicable however at aynho jn, over the flyover, there is a variable speed limit on the down for sprinter class trains (50mph) whereas the linespeed is 85, this is where the local instruction comes into play....

 

172/0 (chiltern units) can take it at 85

172/2 or 3 (london midland) despite being a HST have to take it at the sprinter speed of 50mph as they have an end gangway

158 (if one ever went down there) would take it at 50 for the same reason

165 take it at 75 (unit max speed) as they dont have an end gangway and the speed restriction does not apply to non gangway stock!

 

another local instruction is with the loco hauled set, they run at HST speeds from solihull to warwick parkway (mostly 100mph) however at parkway they have to do 70 as far as leamington (HST speed is 90) then back upto HST speeds to fenny compton

 

also light engine 67s can travel at 100 mph on the chilterns, a 'normal engine' would be 75 max given the linespeeds

 

I've an idea anything conveying four-wheelers had to keep to the lesser speed.

 

apart from pacer units

 

The simulation is set in the early 80's with most Lynn passenger trains 37 hauled. Later they went over to 47's but they were still allowed over the two structures at a higher speed than a 47 hauled freight.

 

you could in your simulation factor in a weight restriction for certain types of freight trains over the structures, the modern equivalent is an RT3973HAW form which lists structures that trains of a certain weight/configuration have to travel at slower speeds over, we used them at fastline with the loaded coal trains, toton high level good s for example had a 20mph restriction bridge over the nottingham line when loaded, linespeed when empty (45mph)

 

regards class 37s in your example, on the cambrian there are a number of bridges that are restricted with class 37s due to the RA index, caersws springs to mind, 10mph over the river bridge, similarly 20301-20305 werent subject to restriction over it but 20306 upwards were due to an extra fuel tank in the nose end

 

there is also a RT3973CON for container traffic which has route restrictions for different sized containers on various wagons, that one being more to do with where the train will fit through structures etc!

[LNERGE]

you could in your simulation factor in a weight restriction for certain types of freight trains over the structures

 

The 'simulation' is not very flexible inasmuch any change is achieved with wirecutters, pliers wire and solder. On my Lynn line up trains of classes 6,7 and 8 (the only classes of freight that use that route) now take 19 minutes to clear Downham to Littleport. Classes 1,2,5 and 0 take 12 minutes. There appears to be a difference of opinion regarding 0 or light loco's though. I have been sent some tape recordings taken on board Lynn road passenger trains. On the up the CWR can be heard to start just as the train starts to slow for the bridges. This section would have been relaid after the derailment. Surprisingly down trains don't slow for the bridges. Also the down line is laid in 60 foot panels and the linespeed is 60 mph. This information arrived in the nick of time as i had just fitted the controlling relay but not started the wiring change to slow down road freights. Phew.

[dmustu]

Dont confuse split speed restrictions with EPS/ MU signs.

 

185s and voyagers are NOT classed as MUs (because of the ridiculous heavy axle load) and must stick to the lower speed on MU restrictions.

 

I dont have a clue about the 185s but Voyagers can run at MU and DMU speeds, as well as HST speeds. They cannot run at SP speeds though.

[Edwin_m]

172/2 or 3 (london midland) despite being a HST have to take it at the sprinter speed of 50mph as they have an end gangway

158 (if one ever went down there) would take it at 50 for the same reason

 

Anyone any ideas why having a gangway should mean the unit has to run more slowly, in some places but not others?

[big jim]

Anyone any ideas why having a gangway should mean the unit has to run more slowly, in some places but not others?

 

not a clue!

[Vin]

Hi all,

 

No wonder this country is in such a state. Loads of rules and nobody knows why!

 

Regards

 

Vin

[The Stationmaster]

Anyone any ideas why having a gangway should mean the unit has to run more slowly, in some places but not others?

The only logical explanation I can come up with is signal sighting - coming over the flyover onto the right hand curve and with the signal (is it still there Jim?) possibly obscured for longer by not having a full width view from the driving position. Dropping the speed will increase the available sighting time and might be a wizard ruse to keep it compliant? Perhaps, maybe?

[Vin]

Hi all,

 

That makes sense but still has more questions than answers. The rules do come from past experiences, be it engineers or drivers. It can't solve all problems on today's congested network. That is where local line knowledge comes into play.

 

Regards

 

Vin

[royaloak]

I dont have a clue about the 185s but Voyagers can run at MU and DMU speeds, as well as HST speeds. They cannot run at SP speeds though.

I was half right at least!

 

Thanks for the correction, I dont drive either and was working off memory and it looks like I got my diferential and SP mixed up just as I warned others about in a previous post.

[big jim]

That is where local line knowledge comes into play.

 

local knowledge stands for very little in this age of signalling arrangements being designed by computer models and mathamatical simulation!

 

regards the 158 restriction at ayhno, there is a similar one at wycome on the up, 50 for gangway sprinters (60 linespeed), both wycombe and ayhno are reverse curves and the ony thing i can think of is should there be 2 units coupled there would be too much lateral sideways movement in the publicly accessable gangway connections between units maybe?

 

edit: thinking about signal sighting mike mentioned, there is also a signal on the r/h bend at wycombe too so that may be the reason

 

i'll ask a man who will know tomorrow and report back my findings!

[Vin]

Thanks big Jim,

 

Your totally right about modern signaling systems but I think the speed limits can be simplified and not just over complicated by 'special permission' signs. I do understand that drivers are issued with notices but we are all human and forget.

 

Regards

 

Vin

[big jim]

i've just been looking through the on line western sectional appendix to try and find a reason for the gangway restriction at ayhno but to no avail, learned a few other bits and bobs though such as class 37s are subject to a 5mph speed restriction for 21 chains somewhere between neasden jn and marylebone on the down!

 

i find that on passenger work the speeds are simple enough as its limited (similar) traction and one core route, freight is more complex though with the various restrictions i mentioned for loaded/empty trains, class of loco etc and of course there is a far larger route card, that IS where good route knowledge comes into play, but as you say vin, we are all human and sometimes we get it wrong or just plain forget

[phil-b259]

i've just been looking through the on line western sectional appendix to try and find a reason for the gangway restriction at ayhno but to no avail, learned a few other bits and bobs though such as class 37s are subject to a 5mph speed restriction for 21 chains somewhere between neasden jn and marylebone on the down!

 

 

How odd, especialy as I would have thought that the 67s Chiltern are using come out with a much heavier exle loading than a 37. Even visability from a 67 would be better with with that large one piece windscreen.

[Edwin_m]

regards the 158 restriction at ayhno, there is a similar one at wycome on the up, 50 for gangway sprinters (60 linespeed), both wycombe and ayhno are reverse curves and the ony thing i can think of is should there be 2 units coupled there would be too much lateral sideways movement in the publicly accessable gangway connections between units maybe?

 

edit: thinking about signal sighting mike mentioned, there is also a signal on the r/h bend at wycombe too so that may be the reason

 

Unlikely I think, as the geometry of the outer end gangway on a 158 or 172 must be pretty much the same as the inner end of a 168 etc and these aren't restricted. I think the signal sighting issue sound like a much more likely reason.