I know the 158 is classed as a HST and that has a top speed of 90mph. Just asking as on Fife circle, the 170 uses the HST speed limits
Is 160Kph considered high speed in the UK? (It is the maximum operating speed of that train). But also from the not exactly aerodynamic-friendly shape of the front and from the (abnormal) front glass one would say that it does not wink at high speed. For me (and I think also for Europe) the Javelin is the entry level of high speed.
In reality wouldn't a class 170 driver be on a similar pay grade to drivers on local trains as opposed to intercity units i.e Voyagers and IET's?
More info on the HST speed boards can be found on RSSB website, but you need a login if you don’t have one. There’s also this thread but it isn’t straight from the horses mouth: https://www.railforums.co.uk/threads/what-are-hst-speeds-applicable-to.213936/ It might even say it in the above thread, but my understanding is it is to do with the better braking characteristics, as (obviously) braking distance for signals is a limiting factor for speed. This does not mean that the 170 or 158 or any other train on that list is a HST, it is just that the speed board was introduced for the HST (class 43 like you say) but since then other trains have qualified to be permitted at that speed due to their braking.
As the link to the railway forum says, the HST refers to the 'disk braked' trains, rather than brake shoes. HST has no reference to the 43
From what I know, the Class 43 (HighSpeedTrain aka HST) has the same operating speed as the 395 Javelin or the even more recent 800 Azuma. All of these trains can operate at a maximum of 125 mph. Which for me, who have always been used to what is seen as the high speed standard in the world, is the minimum, the entry point for high speed. The Railjet, which has the structure, construction and technical characteristics of a modern Intercity/Eurocity in Europe, is seen more as a fast train than a high-speed train (and forgive the pun). Do you remember the 70s-80s and the European TEE Trans Europ Express? Those were trains that about 40 years ago ran across half of Europe at 200 kph. 40 years later, the Railjet raised that standard by 30kmh. So today Intercities and Eurocities have as a reference the maximum speed between 200 and 230 kph. The real high-speed trains here in Europe (and I believe also in other places on the planet such as South Korea, Taiwan, Japan and China just to name a few, are the TGV, the ICE (the EUROSTAR) and similar such as the Zefiro (Frecciarossa1000 in Italy, Iryo in Spain and various other names based on country and company), those that mostly run on lines dedicated exclusively to high speed (those lines in video games defined by some - many, myself excluded - as boring, because to run at 300 kph and above and maintain a high average speed, you have to cut through the mountains, not circumvent them) which as you will have noticed are structurally very different from the fast ones that the Railjets mostly travel on. Of course, it is not a firm rule and there are exceptions, but generally they also have fewer stops than a real high speed train. I don't know much about the UK, but I know for a fact that the HS1 which connects St. Pancras to Folkstone and the Channel Tunnel is a real high speed line, designed and built for trains faster than 125 mph . The route we have in TSW4 between Duncaster and Petersborough (I probably got this name wrong) seems to me like a fast line, for Railjet or Trans Europ Express and not a real high speed line like HS1 is. That's all.
The 43/HST has a top speed record of 148mph but is limited to 125mph for service. The javelin has top speed of 140mph in service and the 800 has a top speed of 125 in service.
I'm not a fan of top speeds and even less of records simply because they aren't of much use except to engineers and those who have to develop new solutions. In operational composition and original configuration, TGV (I'm not talking about that Ibido which touched 574.7 kph), ICE and Zefiro V300 touch or slightly exceed 400 kph (about 250mph). And the Shinkansen on rails (no MagLev) probably also reach the same speeds. The old Class 43 HST is a beast for a Diesel. Slow on acceleration but then it flies.
As far as I remember, IETs (with the exception of the Class 810) do have a top speed of 140mph but do not achieve it in service, a similar case to the Class 390 and 91. The ECML is being upgraded however to allow for 140mph operation with the installation of ETCS, and I believe that the GWML is also being considered but I can't tell if that's just me remembering stuff incorrectly. As far as the ECML is concerned, Network Rail is footing the bill for (at least some) trains to be upgraded for ETCS. Whether that includes the Class 379s which are going to be transferred to Great Northern. And one more thing - in the early days of Chiltern, the Class 168s were supposedly meant to be regeared to 110mph but this didn't happen.
High Speed train is more of a marketing term. For example when line speed on the WCML was raised to 110 MPH for loco hauled trains, they were not suddenly rebranded “high speed”. What you will find however are differential speeds for trains formed of lightweight passenger stock such as DMU's, HST's etc. versus heavier loco hauled formations. And ironically when the Class 175's first started working on the Marches Line due to the weight were not permitted to operate at Sprinter line speeds where there was a differential, but the lower loco hauled speed.
