Edwin_m

That might be quicker London to Sheffield and Birmingham to Leeds, but London to Leeds by that route would be slower than the ECML.

In Hertford, Bedford and Cambridgeshire, hurricanes hardly happen.

There was certainly some concern about trams falling off viaducts when I was involved in the hazard workshops for Metrolink Phase 3. I seem to recall Irk Valley Junction has a speed restriction for that very reason. Getting back a bit closer to topic, there is now a fairly authoritative fightback against the proposal to demolish a swathe of Bedford to widen the MML to six tracks for a mile or so: https://bedfordrail.wordpress.com/2021/05/22/east-west-rail-2021-consultation-wrap-up/

Not quite that bad now, the industry has got used to the need to do risk assessment and obtain derogation and it doesn't seem to be a problem on recent schemes. However a (safety) risk assessment is always itself a (project) risk, because if it doesn't give the answer you want or it isn't approved by the relevant people then you need to change your design and incur extra cost, quite possibly at a point where it delays completion of the whole scheme.

There was a collision on the junction where the lines from Bury and from Newton Heath converged above the Irk Valley (now the junction of the Metrolink Bury and Oldham lines), sending one of the trains off the viaduct.

Being a graduate trainee with BR Research and wanting to test some on-train equipment, I got a free ride on Lab 5 which was recording track geometry on the same route as part of the same investigation. I was subsequently a little involved with: the Track Circuit Assister (or Actuator), which was attached to the bogie and circulated a high frequency current through the wheels and rails which was found to reduce the resistance and give detection in normal conditions. the TCA Interference Detector, which could detect the signal from the TCA and short the track circuit, fitted to locations where contamination was too heavy for the TCA on its own. the One Shot Emergency Sander, a modified fire extinguisher which could dramatically improve adhesion if operated when the train needed to stop in very poor conditions, as illustrated on a memorable early morning run with the first ECS out of Salisbury one November. This was the forerunner of more sophisticated sanders now fitted to (I think) all multiple units.

Also the 158s on the Cambrian.

I think it was "Three Men in a Boat" that proposed the Victorian alternative of carrying a particularly pungent cheese in your luggage. Anyone else occupying the compartment tended to move out after 10 minutes or so .

From the HS2 thread: That is one possibility, and a shared model would reduce vehicle ownership and reduce problems associated with mass production of batteries, as well as making it more likely that people would consider alternatives for a particular journey. But it raises a whole lot of other questions about whether a shared vehicle is in a fit state to be used by the next person. Imagine what some of them would be like on a Saturday night! It depends on property values. If cars are self-driving then car parks will gravitate to less expensive areas, which still means extra mileage and congestion in the city centre, particularly if reduction in parking charge leads to more people using the self-driving car instead of public transport. Congestion may ration this effect, but any increase in city centre traffic isn't ideal for a whole range of reasons, even if the vehicles in question are electric.

Based on an analysis HS2 published on their website some years ago, almost certainly now removed, the journey time appears to be based on the use of regenerative braking only. Headways are based on using friction braking too, but headway calculations assume that the train in front will stop unexpectedly, which never happens if things are running smoothly. Some sort of train management system should help with this, for example by telling the train behind to hang back if the one in front is about to slow down for a junction. This is a purely financial analysis. However the socio-economic benefits of having Kent better connected to London, plus the socio-economic and environmental benefits of a convenient and low-emission transport link to the Continent, are highly likely to make it a net benefit if the full picture is considered. This does of course increase congestion and emissions, as all the self-driving cars return to their parking spaces after dropping people off in the morning and vice versa in the afternoon.

Even with yield management and some silly low fares, the number of air passengers between any UK city other than London and Paris or Brussels wouldn't fill one Eurostar per day. Air has the advantage of offering a choice of departure times each day, and (increasingly so the further it is beyond London) a shorter journey time, so it's highly improbable North of London would fill a Eurostar. It's possible that it could have been filled by a combination of domestic and international journeys, as is necessary for almost every other international service, but our rules requiring all passengers having to undergo border formalities and baggage screening effectively rules that model out.

The increased separation of trains at higher speeds affects how many trains the line can carry, not how many runs a train can do in a day. On most lines this is dictated by station stops, not by the capacity of the lines in between, and HS2 station track layouts are designed so the line as a whole can operate 18 trains per hour. There's absolutely no reason why faster trains would need longer station turnarounds. In fact if the journey is shorter (in time) the turnaround is probably also shorter, because passengers will have left less litter and there is likely to be less catering therefore less re-stocking. The trains and infrastructure may require more maintenance, though they are doing things like using slab track on the busiest sections to minimise this. But the route will be closed for several hours each night so train and infrastructure maintenance can be done then. As mentioned above, HS2 will replace the fastest trains on the WCML For example three trains per hour (pre-Covid) between London and Manchester on the WCML (with very few intermediate stops) will be replaced by three trains per hour on HS2. 11-car Pendolinos about 250m long will be replaced HS2 sets 200m long but coupled in pairs at the busiest times. This is a significant uplift in capacity, but it is planned to allow for growth in passenger numbers over many decades. By taking the fastest trains off the existing routes, more will be able to stop at intermediate stations that may not get a very good service today. Private capital is a mirage - unless the private sector can find some huge efficiency gains, it just pushes the cost onto future generations at higher rates of interest than the government can borrow money at. That would be the same even if HS2 fares income was going to pay back the capital, which it isn't. HS2 is likely to cover its operating cost but the projected benefit to the economy as a whole make it worth building despite this.

As power generation shifts increasingly to renewable sources, electricity consumption becomes much less of an issue. Electric cars are relatively efficient today, but there will always be losses in putting the power in and out of a battery compared to feeding it directly to the traction equipment. The battery itself has significant environmental challenges, and far more concrete and earthworks is needed to carry the same number of people on a motorway than on a railway. High speed rail is competitive with air travel up to a much greater distance, up to around 500 miles, once the time taken travelling to and within the airport is taken into account, so has greater scope to attract passengers out of a much less environmentally friendly form of travel.

That ignores the fact, well-known by specialists in the field, that roadbuilding generally increases traffic, reduces the number using public transport and transfers the congestion from the bottleneck just addressed to the next most serious one along the route.

Spending on further HS2 extensions is a long way in the future, so shouldn't really be impacted by shorter-term issues. A relatively small spend now on design work, consultation, legal powers etc helps to get the schemes shovel-ready in a few years time, and the decision can be made then on whether to proceed with the big spend on construction. As to roads, there is also the incompatibility of spending £27bn (in a much shorter timeframe than HS2) with the government's decarbonisation agenda, which most experts agree won't be achieved by simply replacing all vehicles with electrics and otherwise continuing with business as usual. They may see that as a more eco-friendly way of reducing spending.

That was the original concept, although it was always intended to run through to Liverpool, Preston, Scotland and Newcastle. With the Higgins review and more recently NPR and the latest rail review, it's got rather more integrated with more off-route destinations (Stafford, Stoke, Macclesfield and Sheffield in current plans and possibly others to come), and particularly NPR services that plan to use bits of HS2 where there is spare capacity. So adding Derby and Nottingham would be in line with this, though it still creates the problem I mentioned above.

The people who benefit are generally older and wanting to downsize or pass the money on to their families. Other people may feel good because they are on paper richer, but if they sell their houses they will have to buy another one or rent, both at prices inflated by property values. These groups of people are more likely to vote than the ones who lose out.

The snag there is that faster trains from London to Nottingham would use up paths on HS2 out of Euston that are currently planned for Leeds and NE services. If HS2 was later extended northwards then there would be a choice between an outcry from Nottingham if these are withdrawn, and not running as many trains further north as originally intended and promised. Derby has the same problem to some extent, but could be partly solved there by routeing the Sheffield trains that way.

The HS2 eastern leg as currently proposed misses Leicester, runs midway between Derby and Nottingham (no through service to any of them), misses Sheffield (although with a through service) and finally throws a branch into Leeds. By the time it gets to York it's so roundabout that it's less than 30min quicker from London than the existing route. It still has benefits, not least speeding up the very slow axis between Birmingham and Yorkshire or beyond, and relieving ECML capacity (though that's much less critical than WCML). But it's not difficult to see that simple geography makes it less attractive than the western leg, which can serve Manchester directly and provide a much better service to the other centres of the North West that aren't directly on the route.

That really takes the biscuit.

It's possible, but I think if they were attaching to the main beams they would have put those in first and done the attaching, then the remaining beams could have gone in at leisure. If they've installed temporary supports then they will have to get the crane back to lift in the missing beams in a future possession. And if it's all within one long possession then there'd be no need for temporary supports, just tie the wires back to something to keep them out of the way.

Just visible further back, and more so on other forums, the apparent "gaps" in the beams are where the main OLE supports are, which appear to need extra height so are on some sort of shallower structure. There are also intermediate OLE supports, which are fixed to the full-depth beams but are simpler assemblies just locating the catenary wire horizontally.

I read the associated article on the BBC website (which has now dropped off the home page and the useless search function doesn't find it). I took it as saying they would locate the convertor in the exchange or the cabinets so the final link to the home remained analogue, unless someone paid to have fibre to their property. That would save the massive cost of changing the connection to millions of homes, including the need to enter the properties in question.

I think the Marches line was one of those that got SP differentials in Regional Railways days. Are they being, or have they been, changed for MU ones?

It's a bit lost in the mists of time, but as I understand it SP was related specifically to low track forces, and those for Sprinters would be much lower than for HSTs. It allowed speeds to be increased for 158s in particular without doing much work to the track, and I believe SP speeds above 75mph were also based on braking distances with disc brakes, since the tread-braked Sprinters are limited to that speed. I believe the policy is to replace SP by MU differentials where possible.