Singha wrote:>>conducting feasibility study on Chennai-Bang HSR corrdor.
the chinese at their own cost conducted a feasibility study of the mysore-blr-jolarpettai-chennai line for HSR and rightly declared it unfit even for semi HSR. too many sharp turns , too steep slopes etc .....
so any blr chennai HSR will need to be new route parallel to the proposed expressway via chittor route....
I do not know what were the conclusions of the Chinese study. Ruled gradients on TGV's are 1:28, far steeper than 1:37 that you find on both Bhor and Thull Ghats out of Mumbai towards Pune and towards Bhusawal. The Bhor and Thull ghats are the steepest gradients on Broad gauge on IR. Nilgiri railways has 1:12.28 for example as ruling gradient.
That is on the Bhor and Thull ghats for every 37m you travel on track you climb or descend 1m, so Sin theta =1/37, where theta is the slope angle, NOT the calculus Tan \theta though for small angles like for the railroad track on Thull and Bhor ghat they are very close by a famous limiting theorem !! My source for ruling gradient on Thull Ghat is 1:37 is wikipedia:https://en.wikipedia.org/wiki/Thal_Ghat
The terminology ruled or ruling gradient simply means that the maximum slope on the line is x:y, so 1:37 is the maximum slope on the Thull ghat, at other places on the Thull ghat section it could be less 1:50 say. x:y dominates or rules.
Here is a list of gradients on other lines, including the Frankfurt-Cologne high speed line and the French LGV Sud-Est all steeper than Thull Ghat:https://en.wikipedia.org/wiki/List_of_s ... n_railways
Look at the last item in this list above: LGV Sud-Est line has a ruled gradient of 1:28, steeper than Bhor and Thull Ghat. In the Satpuras, between Nagpur and Itarsi the ruled gradient is 1:70. Both sections (Thull, Bhor ghats, and Dharakoh-Ghoradongri, and Chichonda-Teegaon in Satpuras, Chennai-Delhi) need bankers because standard IR coaches are heavy. Chennai-Bangalore is nowhere near as steep as these gradients. For freight these steep slopes are taboo and DFC is aiming for a ruled gradient of no more than 1:200. Thus the southern alignment towards Chennai of DFC will involve new routes to negotiate the 1:70 ruled gradients
and maintain the 1:200 ruling.
I had shown once by a simple calculation (see my old posts where the details of the calculation are given, it is a trivial, dumb and cheap calculation!!) that with 1.5km train lengths on DFC rakes, a gradient of more than 1:150 would put tremendous force on the couplings and also speeds would be curtailed if average speeds which are in the 80kmph are to be maintained.
Between Delhi and Chandigarh, before talking of HSR, let dumb Northern Railway double the tracks. It has taken over a decade and a half and they have missed the deadline 7 times, not once, not twice but 7 times. So finally this March 22, CRS will conduct the inspection of the "finally" doubled Chandigarh to Delhi track. The last section is between Dhappar-Chandigarh, 23 km and all this tamasha was for Ambala to Chandigarh doubling a grand total of 46km. If 46 km doubling takes 15 years https://timesofindia.indiatimes.com/cit ... 029045.cmshttps://timesofindia.indiatimes.com/cit ... 925952.cmshttps://dailypost.in/news/chandigarh/ra ... ble-track/
I am always amused seeing all this HSR talk when one cannot even complete simple projects in a time bound manner. As far as I recall SNCF pointed out that removing 12 curves between Chandigarh and Delhi and eliminating some level crossings would allow IR to run trains at 160-200 kmph with off course improved signalling. That is the French input apart from developing some railway stations. But curve elimination resulted in LA issues. Now they plan to run Gatimaan type trains after doubling is inspected by CRS.