...I'd also rather it had a slightly reduced top speed (cutting it to 202mph would save a lot more electricity than it would extend journey time, and it's capacity that's needed more than speed, might be able to avoid any important wildlife habitats slightly more easily too)
Well, it is of course true that energy consumption increases signficantly with speed, however we can't look at the energy used by the trains in isolation from the other modes that people might use instead. Lower speed means longer journey times and that has a large impact on HSR's competitiveness with air and road. So while a reduced speed high speed train will use less energy, it is likely to carry fewer passengers and take fewer from air and road. There is therefore a compromise between the energy used by the train and the ability to attract passengers, however deciding where the optimal speed lies requires complex modelling, taking account of alternative modes, you can't simply assert that an arbitrarily chosen lower speed (precisely 202mph???) will be better.
I'm afraid I cannot remember the source, but seem to remember a graph which showed a fast enough HighSpeed train on the
UK▸ 's electricity mix could have a negliable, perhaps even non-existant, reduction in emmisions over car transport. Therefore, I felt that for me to support
HS2▸ it would have to be a compromise between being fast enough to tackle domestic aviation but slow enough that obtaining modal shift from road to HSR would result in a drop in emmisions.
I fear your "adjustments" would involve vastly more tunnelling and hence increases in cost.
Vastly more tunneling, or small increases in tunneling with some track built on a deck above motorways (still expensive might be cheaper than the all tunnel option), would be needed yes. However, it would allow all trains to go beyond Birmingham. A new 140mph line could beat road travel on journey time easily and there's no aviation to compete with on the London-Birmingham leg, therefore no need to push up electricity useage to go faster unless you can go beyond Birmingham after calling there. That's also much better use of capacity, if you want to give Birmingham and Manchester 3 trains per hour each on the government's planned route, you use six paths over the line into Euston. However, route the Manchester services via a central Birmingham through station and you could give both cities 4 trains per while only using that number of paths into Euston.
I guess it really depends on just how massive the increase in cost would be and whether the advantages of Birmingham being a through station would warrant that cost.
I believe the phrase you are looking for is 'number plucked out of mid-air', which naturally leads to the expression 'silly plucker'.
(precisely 202mph???)
I believe the phrase you are looking for is 'number plucked out of mid-air', which naturally leads to the expression 'silly plucker'.
There are 160944 mm in one mile ... so 202 mph is 325 kph. I'm suspecting a piece of work done in a metric country that showed that a speed between 320 and 330 kph is optimum for something.
Sources, please, Rhydgaled Nothing saying it is 'optimum' per see, but you've realised the 202mph figure is based off it being roughly equal to 325kph. If you take 325kph as 202mph and 360kph as 224mph I think the time difference is only around 1.75 seconds per mile, or 1.4586 mins over 50 miles.
I used a graph on page 15 of this document:
http://www.hs2.org.uk/assets/x/56774 to try and estimate kWh per seat kilometre figures which came out at 0.054 for 360kph, 0.048 for 330kph and 0.047 for 320kph.
Using the carbon intensity figure of 455 grams of CO2 per kWh from
http://www.rssb.co.uk/SiteCollectionDocuments/pdf/reports/research/T618_traction-energy-metrics_final.pdf, I estimate emmisions (gramms of CO2 per seat km) of 24.57 for 360kph, 21.84 for 330kph and 21.385 for 320kph.
I chose the presice 202mph figure for publicity reasons. Firstly, since it is just above 200mph you can say you have 200mph trains, or that you have trains that can exceed 200mph. Now, since we use miles in this country, 200mph would make sense. The only reason I didn't use that figure is by going to 202mph you could call the trains Intercity 325s. If you don't think that particular trick would be good marketing then ok, 200mph would be a better figure to use.
So now you know, I didn't just pluck a number out of the air at random.
It is rather worrying that both the quoted studies, although being produced for British use, are using kilometres rather than miles. Since we didn't adopt metric measurments for distances back when we adopted them for weights and have speed limits signs displaying miles per hour all over the country I think we should stick with miles.