Are Top Speeds Really Just the Recommended Speed?

[whhistle]

90's are okay...a bit light footed - especially in the wet. I don't mind the fact that they don't do 125mph..as it means they get driven flat out..provided the rails are dry.

Taking this example of a Class 90 loco, I am sure it could do quicker than the top speed. If so, why is the top speed rated at that value?

The HSTs (for example) can do quicker than 125mph, despite a lot of speed restrictions at this limit. Is the 125mph just the operating top speed recommended by the manufacturer? I mean, have a flat line and open the throttle and I'm certain an HST would go faster.

So if an HST went on the HS1 route, why can't it go quicker than 125mph?

I may be confusing two different approaches here, as I guess there will be infrastructure restrictions, compared with trains that physically cannot do quicker than the quoted top speed.

 

[Islineclear3_1]

The top speed is probably the "capable" speed +/- a small variance either side but obviously, this depends on many factors such as line conditions, gradients, load, driving style, signal aspects etc...etc

 

[gordonthemoron]

Wasn't the fastest an HST reached something like 147mph on Stoke Bank? Granted it only had 5 coaches. 91's can do 140mph as can pendolinos

 

[a_c_skinner]

In the anorak and ABC world it is widely held that Western Region 125s often ran at up to 135mph if they needed to make time. You cannot now of course.

 

[gordonthemoron]

In the anorak and ABC world it is widely held that Western Region 125s often ran at up to 135mph if they needed to make time. You cannot now of course.

I was told that a 125 reached 150mph through Swindon in 1983, though that isn't recorded anywhere

 

[gordonthemoron]

I've also been on an ICE3 between Frankfurt and Cologne that reached 320kph, it's not supposed to exceed 300kph in Germany

 

[gimmea50anyday]

I have clocked 132mph according the the TMS on voyagers between Didcot and Reading. OOC drivers wanting to get home on late shifts no doubt...

 

[tiptoptaff]

The main reason for not exceeding 125mph is that above that, lineside signalling becomes too difficult to read. Hence the use of in-cab signalling on high speed lines

 

[AlexNL]

It's not uncommon for trains or locomotives to be capable of going much faster than what they're authorised for.

For example:
- ÖBB Taurus 1216 locomotive, top speed 230 km/h. 1216 050 has done 357 km/h (yet, that's a three!) under test.
- Siemens Velaro E, top speed 350 km/h, in 2006 hit 403.7 km/h while under test in Spain
- SNCF/Alstom TGV V150, a modified TGV Duplex train, reached 574.8 km/h while under test in France

Trains are often confined to certain maximum speeds which are an optimum between performance and maintenance. Going much, much faster will require the vehicles to meet tougher crash regulation standards (driving up the procurement price), drives up the costs to run the train (fuel/electricity consumption) and necessitates more intensive maintenance regimes.

 

[driver9000]

The maximum authorised speed for traction or rolling stock is exactly what it says it is - the maximum authorised speed. Go over it and you're leaving yourself wide open for speeding charges and some may go down the "safety of the line" route but that would be extreme.

Maximum speeds are determined by all manner of factors and just because a loco or unit may go over that speed doesn't mean you can or should.

 

[Wivenswold]

Having disciplined drivers in the BR days for speeding I can assure you that it's never been acceptable and has led to the termination of employment for repeat offenders. What has changed is the ability to monitor speeds and that has had a positive effect not only on instances of speeding but the general downturn of speed-related incidents in the UK. Drivers know now there's a greater chance of being caught and generally take it very seriously too.

You would always have a union rep in the meeting and they would always provide a mitigating statement but it was generally understood that this was sometimes utter nonsense and a thinly veiled plea for clemency. However, there were some genuine mistakes so we didn't assume guilt. People make mistakes, you have to allow for that but it was interesting that in those instances, the driver usually held their hand up and apologised rather than spinning a story.

 

[Railperf]

Most modern rolling stock has to be capable of operating safely and reliably at least 10% more than its planned service speed, and during those tests the equipment clearly has to be capable of more than that .. to avoid falling apart / failing / damaging the infrastructure.
Safety and operational issues dictate how much of a train's maximum service speed is allowed in daily service.
East Midland HST's timings are based on 110mph running for instance.
One -off speed runs, such as the record breaking Tees Tyne Pullman HST run between Newcastle and London where a shortened 2+5 HST achieved over 140mph with passengers aboard ran under strict operational rules.with the emphasis on safety. Speeds over 125mph were only allowed on specially designated sections of track. The train was specially prepared with mechanical standards set far higher than a normal service train. The driver would have had close supervision. Signallers were ordered to keep the line ahead clear where possible and prevent the chance of this special run running into traffic.

 

[gingertom]

I read in Wiki that the class 90 was designed as a 125mph loco. In testing it was decided the brakes needed upgraded. This was never done (expensive modifications needed, not authorised?) and was therefore restricted to a service speed of 110mph.

 

[bramling]

The maximum authorised speed for traction or rolling stock is exactly what it says it is - the maximum authorised speed. Go over it and you're leaving yourself wide open for speeding charges and some may go down the "safety of the line" route but that would be extreme.

Maximum speeds are determined by all manner of factors and just because a loco or unit may go over that speed doesn't mean you can or should.

Speeding was certainly rife on LU as recently as the 2000s. It was virtually standard practice on some sections to try and get the needle “off the clock”. On something like a 59 stock this would be 60 mph. Having said that, I forget what the actual official top speed of a 59 stock actually was.

Nowadays on-train monitoring equipment is virtually standard across LU, I think the only one which doesn’t have it is the Bakerloo. Have an incident and the download shows speeding and the driver will be in hot water, especially if someone like the ORR get involved.

 

[bengley]

Speeding was certainly rife on LU as recently as the 2000s. It was virtually standard practice on some sections to try and get the needle “off the clock”. On something like a 59 stock this would be 60 mph. Having said that, I forget what the actual official top speed of a 59 stock actually was.

Nowadays on-train monitoring equipment is virtually standard across LU, I think the only one which doesn’t have it is the Bakerloo. Have an incident and the download shows speeding and the driver will be in hot water, especially if someone like the ORR get involved.

I've been on A stock on the Chesham branch (35mph) which has been travelling at up to 60mph on parts of the branch. 'Lively' describes the ride pretty well! This was fairly common back in the days of A stock as they had no OTMR.

I have also certainly ridden S stock which has been speeding by some margin on the branch too, so it's not totally been stopped even with OTMR on the train.

 

[JohnMcL7]

I have been curious why the 92 is just 87 mph? Is that because it was intended for freight rather than passenger service?

 

[dubscottie]

I read in Wiki that the class 90 was designed as a 125mph loco. In testing it was decided the brakes needed upgraded. This was never done (expensive modifications needed, not authorised?) and was therefore restricted to a service speed of 110mph.

The 90s are more than capable of 125mph. They would need disc brakes however. Tread brakes would be too expensive to maintain and a fire risk with regular 125mph use.

 

[ge-gn]

I have read somewhere (possibly traintesting) of a class 86 being run at 130mph for aerodynamic testing in the early 70s.

That would certainly suggest that locos are capable of doing above the maximum authorised speed. However, as mentioned above many factors must determine what the maximum authorised speed is including physical, safety, cost of increased maintenance etc.

In the physical sense I guess you could think of it in the same way as your car. The red line may be at 5500rpm. It will go over that to perhaps 6500rpm, but the damage being caused by going that fast would cause costly damage. Is that a fair analogy?

 

[Journeyman]

I have been curious why the 92 is just 87 mph? Is that because it was intended for freight rather than passenger service?

Yes, they're geared for high tractive effort for heavy trains, rather than speed. The only passenger services they were intended for were sleepers (although not the ones they're currently operating!

 

[Ash Bridge]

I have been curious why the 92 is just 87 mph? Is that because it was intended for freight rather than passenger service?

Originally intended for freight and Nightstar sleeper services.

 

[snowball]

I have read somewhere (possibly traintesting) of a class 86 being run at 130mph for aerodynamic testing in the early 70s.

That rings a bell. I think it was fitted with an HST-style front end as part of the development work for the HST.

 

[61653 HTAFC]

I have been curious why the 92 is just 87 mph? Is that because it was intended for freight rather than passenger service?

If you mean why 87 As opposed to 90, it's to do with conversion from km/h to mph. 87mph being 140km/h.

 

[Far north 37]

I have clocked 132mph according the the TMS on voyagers between Didcot and Reading. OOC drivers wanting to get home on late shifts no doubt...

Not sure old oak common drivers would ever have been passed on voyagers would they.

 

[Bletchleyite]

I have been curious why the 92 is just 87 mph? Is that because it was intended for freight rather than passenger service?

It's 87mph because that's 140km/h, a more round number - this is a similar reason why lorries are limited to the seemingly odd 56mph (90km/h) and coaches to the similarly seemingly odd 62mph (100km/h). I suspect because of the intended use, yes.

 

[captainbigun]

The 90s are more than capable of 125mph. They would need disc brakes however. Tread brakes would be too expensive to maintain and a fire risk with regular 125mph use.

This is not true. 86/1, 87 and 90 all nominally run the same bogie and traction motor. 90 has low voltage field windings which support the SEPEX. The drive is designed for 110mph, that factors in maximum rotational speed of the traction motor on the smallest wheels. So to the analogy of where the red line is in your car, running over 110mph risks overspeeding the traction motors.

Then you look at the track forces exerted. The bogie and unsprung weight are not designed for >110mph running. Track forces would become problematic.

Yes, you could run one of the above over 110mph and on full size wheels it *might* be OK. But it's not designed to do so.

89 has tread brakes and is 125mph capable. Tread brakes are not an issue. What is missing is the ability to brake to a stand on the rheostatic brake with no overhead supply. A 90's field supply is from the overhead. It can electrically brake off of the overhead for a short time, say 5 seconds, by cross feeding motors, but it certainly cannot brake to a stand. This would require another set of batteries to provide the field supply and a completely different field converter arrangement.

Do not believe Wikipedia!

 

[Bletchleyite]

That rings a bell. I think it was fitted with an HST-style front end as part of the development work for the HST.

Wasn't that the one-off Class 89 which did look rather like an HST? (Though the rest of it looks more like a 90 or 91).

Class 89 in GNER livery

 

[Darandio]

Wasn't that the one-off Class 89 which did look rather like an HST? (Though the rest of it looks more like a 90 or 91).

Class 89 in GNER livery

That was long after development of the HST though.

 

[Darandio]

I'm guessing this is it? Image from: http://www.traintesting.com/high_speed_testing.htm

 

[Highlandspring]

Wasn't that the one-off Class 89 which did look rather like an HST? (Though the rest of it looks more like a 90 or 91).

Class 89 in GNER livery

No, it was E3173 in 1970 -

 

[JohnMcL7]

If you mean why 87 As opposed to 90, it's to do with conversion from km/h to mph. 87mph being 140km/h.

I wasn't meaning the 87mph value specifically, the class 90 and 87 had higher 110mph speeds and the 92 seems quite low in comparison given it's a powerful engine. I assume the trade off is it's much better for freight although I always think of 92's in passenger service as my only experience with them is on the sleeper.

On the subject of top speeds did the 67's ever run at 125mph? Assuming that figure on wikipedia is correct as it seems high when the 68 has a maximum speed of just 100mph.