"170s are too slow off the mark for stopping services"

[pemma]

This is a claim we keep seeing posted on here. Where it has this claim originated from?

We know replacing HSTs with 170s on MML routes didn't improve journey times (despite loco-hauled needing longer dwell times and generally being seen as slower off the mark) and that replacing 158s with 170s on CT routes didn't improve journey times (despite 158s being 90mph and 170s being 100mph.)

However, a joint TfGM report looking at the possibility of tram-trains on the Mid-Cheshire line (which pre-dated 172s being introduced) stated that a 170 running between Altrincham and Greenbank calling at all stations could get to Greenbank 26.9 minutes after leaving Altrincham (TfGM used figures provided by Network Rail.) Currently the service is timed for a 142/150 arriving at Greenbank 32 minutes after leaving Altrincham. Some of that extra journey time would be down to longer dwell times required for Pacer with only 3 sets of doors instead of 4. However, it seems the Pacer's acceleration is seen as inferior to that of a 170 on sections of line with frequent stops and there could be some significant journey time savings by using 170s instead of 142s on longer routes.

I also understand Network Rail looked at how 170s would perform on Hope Valley stoppers and came up with similar results but I've not seen the actual timings for that.

 

[317666]

I think it was reported on here not so long ago that a 170 can out-accelerate a 142 - in Norfolk they struggle to keep to time on 153/156 diagrams though.

 

[pemma]

in Norfolk they struggle to keep to time on 153/156 diagrams though.

Do you mean single 153 diagrams or diagrams including a 153 e.g. 153+153 or 153+156?

153s on their own don't have a lot of power so I'd find it surprising if any 2 car DMU can't keep 153 timings. Maybe if there's platforms which can only just take 2 car DMUs I can understand why as stopping a 2 car DMU would require more precision from the driver than a single car train.

 

[scotraildriver]

You also have to be very cautious with low speed braking on a 170 as they have a tendency to "run away" from you so drivers will be very gentle with their braking increasing journey times. Hit the brake on a 170 at 100mph it is great, 10mph it is rubbish!

 

[simonmpoulton]

How do they compare with say the 175's as they are a similar age of unit?

 

[RobShipway]

Also, I am suspecting that the same issue is seen with braking at 10mph with Class 165/166/168/172's as they are from the same family or do they have different braking to the class 170's?

 

[TDK]

How do they compare with say the 175's as they are a similar age of unit?

I cannot vouch for 170's but the 168 brake is better than a 175 from speed and at low speed by far. The 175's used have very sharp brakes but the introduction of vented disks and different pads dulled the brakes somewhat, however 175 brakes are very good but 168 brakes are better. To add the 168 has a 3 step brake where a 175 has a continuous brake from low to high so weight must be taken into consideration with a 175 where with a 168 it doesn't as they have levelling bars to compensate the brake pressure in the steps. A 175 has the same system but without the stepped braking you need to know when to put in that little bit more brake when under load.

 

[47802]

Of course would you actually put a 170 on such short distance stopper as suggested, even if they actually come to Northern which I doubt I would say they are a number of medium distance services they could be more suited such as Calder Valley, Leeds Nottingham etc, while the suggested route would be more suited to a 150. I agree if northern did get some 170's it might be a bit of balancing act as to where they would be best suited to and where any displaced 156's/158's might go.

 

[pemma]

Of course would you actually put a 170 on such short distance stopper as suggested, even if they actually come to Northern which I doubt I would say they are a number of medium distance services they could be more suited such as Calder Valley, Leeds Nottingham etc, while the suggested route would be more suited to a 150. I agree if northern did get some 170's it might be a bit of balancing act as to where they would be best suited to and where any displaced 156's/158's might go.

What short distance stopper are you talking about?

If you mean Altrincham-Greenbank then that's the slow section of the 90 minute service between Chester and Manchester via Stockport. It's actually around the same length as Victoria-Leeds via Bradford.

If you mean Sheffield-Piccadilly stoppers then it's a little shorter than Victoria-Leeds via Bradford but not much shorter.

The 150s don't have ample life left in then so consideration does need to be given to what will replace them if there is no new DMU order (except for a short term solution of converting D78s to DEMUs.) The only DMUs with wide double doors will be Turbostars and 185s with the Turbostars being more suited to rural lines and secondary routes than 185s which would be too costly to use on those types of routes.

Given Northern and Metro strongly defended why 158s are best suited to Yorkshire routes, their defence could actually be used against 170s going to Yorkshire routes especially considering there would be numerous advantages in using 170s on West Side diagrams over 156/8s.

 

[eastwestdivide]

How much of a job to regear the 170s, trading 100mph top speed for quicker acceleration?

 

[notadriver]

If anyone is interested a rail magazine have been doing an articles on the 0-60 times for various rolling stock.

Class 153 : 2m36s
Class 166 : 1m42s
Class 168 : 1m43s (this might be the closest to 170 performance as similar power output and geared top speed)

 

[pemma]

How much of a job to regear the 170s, trading 100mph top speed for quicker acceleration?

I actually wondered that before. However, it's looking like if there is an issue it's coming to a halt from low speeds on some lines not anything to do with acceleration.

 

[47802]

What short distance stopper are you talking about?

If you mean Altrincham-Greenbank then that's the slow section of the 90 minute service between Chester and Manchester via Stockport. It's actually around the same length as Victoria-Leeds via Bradford.

If you mean Sheffield-Piccadilly stoppers then it's a little shorter than Victoria-Leeds via Bradford but not much shorter.

The 150s don't have ample life left in then so consideration does need to be given to what will replace them if there is no new DMU order (except for a short term solution of converting D78s to DEMUs.) The only DMUs with wide double doors will be Turbostars and 185s with the Turbostars being more suited to rural lines and secondary routes than 185s which would be too costly to use on those types of routes.

Given Northern and Metro strongly defended why 158s are best suited to Yorkshire routes, their defence could actually be used against 170s going to Yorkshire routes especially considering there would be numerous advantages in using 170s on West Side diagrams over 156/8s.

Well I know that you seem to be the self appointed expert on all things northern but unless you have a hotline to the DFT do you actually know the 150's will be replaced, I expect not no more than I do, and ok they might get replaced with a new DMU order,, vivarail units, or life extended its anybody's guess at this stage as is the idea that the 170's will come to Northern.

It seems to me that 170's would be best used on medium/to long distances with heavy loading that take advantage of both the commuter door layout and ideally the higher speed limit of these units over a 75mph sprinter. The Calder Valley perhaps not the best choice on reflection but still better than the Greenbank route with its 15 stops as opposed to typically 7 to 9 stops on the Calder Valley semi fast services. As for tying to turn this into a east side west side thing that's just ridiculous

 

[SpacePhoenix]

How well did the Turbostars keep up with the timings when they were used in the Waterloo-Exeter St Davids route (compared with the 159s used now)?

 

[notadriver]

How well did the Turbostars keep up with the timings when they were used in the Waterloo-Exeter St Davids route (compared with the 159s used now)?

Surely (just guessing) a 170 would perform very similarly to a 159? In the table the 166 was geared for 75 and the 168 for 100 but the higher power of the 168 enabled an almost identical 0-60 time.

 

[pemma]

47802 - I said

The 150s don't have ample life left in then so consideration does need to be given to what will replace them if there is no new DMU order (except for a short term solution of converting D78s to DEMUs.)

I didn't say a new DMU order has been completed ruled out. I suggest you read this document: http://www.angeltrains.co.uk/Portals/0/News_Downloads/Rolling Stock Strategy 2014 v10.pdf
and this document:
https://www.google.co.uk/url?sa=t&r...6ubJNf1X8qf0rkHnlvjhPOA&bvm=bv.85464276,d.ZGU

The first one suggests no new large DMU or self-powered order again - ever (there's 135 x class 150s in service) and the second suggests rural lines have some similar characteristics to regional routes so regional stock can be versatile enough to cascade down to rural lines.

The Mid-Cheshire line has 13 stations between Chester and Stockport but the lines goes to 2tph as proposed as part of the Northern Hub only 5 of those stations will be served by all trains, which would make it more similar to the Calder Vale line. Most of the 15 minute run between Navigation Road and Stockport has a line speed of 75mph while between the Stockport viaduct and junction with the Airport line there is provision for even faster running but the trains used currently have a 75mph top speed.

The reason I brought up 158s was because you were suggesting 170s (if Northern get them) go on Leeds area services and then 158s are cascaded to other lines, yet Northern/Metro claim the 158s are currently used on lines where the 158s are best suited to. I'd like the comfort of a 158 on the Mid-Cheshire but on a line where you can get >100 boarding/alighting at intermediate stations and which carries a fair amount of luggage and bikes, a 170 would certainly be better than a 155/156/158.

 

[dk1]

I think it was reported on here not so long ago that a 170 can out-accelerate a 142 - in Norfolk they struggle to keep to time on 153/156 diagrams though.

Not noticed that personally. I seem to keep to time.

 

[Philip]

I cannot vouch for 170's but the 168 brake is better than a 175 from speed and at low speed by far. The 175's used have very sharp brakes but the introduction of vented disks and different pads dulled the brakes somewhat, however 175 brakes are very good but 168 brakes are better. To add the 168 has a 3 step brake where a 175 has a continuous brake from low to high so weight must be taken into consideration with a 175 where with a 168 it doesn't as they have levelling bars to compensate the brake pressure in the steps. A 175 has the same system but without the stepped braking you need to know when to put in that little bit more brake when under load.

Does the isolation of the dynamic brake on the 175s increase the brake pad wear?

 

[61653 HTAFC]

I'd always thought the problem with 170s being cascaded to some of the more "basket-case" routes was their high track access charges due to weight. At least compared to the broadly-similar 172s which have lighter Voyager type bogies. How easy would it be to replace those bogies on a small sub-fleet which could be dedicated to rural lines?

IIRC the SWT turbostars rarely worked West of Salisbury, generally either working Salisbury terminators or being detached from/attached to Exeter services there. No doubt they did make it from time to time though.

 

[TDK]

Does the isolation of the dynamic brake on the 175s increase the brake pad wear?

yes but the unit will use a lot less fuel reducing the carbon footprint and also saving money.
--- old post above --- --- new post below ---

If anyone is interested a rail magazine have been doing an articles on the 0-60 times for various rolling stock.

Class 153 : 2m36s
Class 166 : 1m42s
Class 168 : 1m43s (this might be the closest to 170 performance as similar power output and geared top speed)

I cannot see how rail magazine can get an accurate measure on this as fuel tank content, passenger numbers, gradient, ambient temperature, time from last "C" exam will also affect the performance of a unit, no unit is the same on performance, some are good, some are average and some are really bad within the same class. By the way 0-60 class 67 light engine 45 seconds
--- old post above --- --- new post below ---

I'd always thought the problem with 170s being cascaded to some of the more "basket-case" routes was their high track access charges due to weight. At least compared to the broadly-similar 172s which have lighter Voyager type bogies. How easy would it be to replace those bogies on a small sub-fleet which could be dedicated to rural lines?

IIRC the SWT turbostars rarely worked West of Salisbury, generally either working Salisbury terminators or being detached from/attached to Exeter services there. No doubt they did make it from time to time though.

It's not the bogies but the actual axle weight that is a measure for track access charges I believe. Correct me if I am wrong!

 

[61653 HTAFC]

You probably know better than me. Nevertheless lighter bogies means lower overall axle weight. I do remember seeing something on these forums about track access charges, and 172s were listed as a fair bit lower than 170s.

 

[Starmill]

170s on 'small' railways feels very strange. You can see why the track access charges are somewhat higher too, where a 153 sort of bounces along, a 170 can seem to grind. I swear there used to be bits of single track on the East Suffolk line where you could hear it creak under the weight of a 3car 170! (although that could have been the train itself, the GA turbostars are right old rustbuckets compared to the rest of them!)

 

[notadriver]

TDK its an average. They try to find a bit of level track and time several runs in both directions. Its not scientific but it gives a fair idea to those interested.

 

[physics34]

You also have to be very cautious with low speed braking on a 170 as they have a tendency to "run away" from you so drivers will be very gentle with their braking increasing journey times. Hit the brake on a 170 at 100mph it is great, 10mph it is rubbish!

100% agree with you. (i drive 171s for southern)

There seems to be no normal braking "curve" (i think thats the technical term!")
...i.e the braking becomes better with the same brake pressure the more the train slows down....