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Electrical Multiple units (Train sets) for higher train speeds on IR

By on December 28, 2014

An energy efficient, cost effective, modern technological solution for increasing average train speeds and throughput of Rajdhani, Shatabdi and other Mail/Express Trains

The biggest criticism Indian Railways face today is that despite developments in Traction Technology and high speed trains running at 350 kmph plus, a reality today, average speed of even the fastest Rajdhani, Shatabdi trains continues to be as low as 90 kmph. Although the maximum permissible speed of these trains have gone up to 150 kmph.

Main reason for lower average speeds of IR passenger trains are:

  • Heavy congestion on major trunk routes
  • Large number of permanent and temporary speed restrictions on trunk routes. On date there are as many as 135 speed restrictions on NDLS- HWH section.
  • Differential speeds of trains. Freight trains, commuter trains and passenger trains run on the same track.
  • Longer trains being driven by single loco. These Important trains having 21 to 24 coaches are being hauled by single loco.
  • Absence of Electrical brakes

Indian Railways is fast losing its competitive edge vis-à-vis Airlines due to its inability to run trains faster and reduce the run time. Various options being considered by IR to systematically increase the train speeds are:

  • Dedicated high speed corridors for running trains at speeds above 250 kmph on certain selected routes under PPP.
  • Gradually up grading the speed of the existing track infrastructure to run semi high speed trains at 160 kmph to 200 kmph.
  • Dedicated Freight Corridor (DFC) for segregating freight traffic and reducing congestion on trunk routes.

These options are time consuming and highly capital intensive as they are dependent on new infrastructure or massive up gradation of existing infrastructure. The need today is to optimally utilize the existing infrastructure and increase the average speed of the trains and carry more passengers by utilizing the modern traction technology.

Most of the Railways in advanced countries in the world, have progressively switched over their intercity passenger services from locomotive hauled trains to distributed powered EMU Train sets. Most of the intercity passenger trainswith operating speeds ranging from 130 to 160 kmph in various countries in Europe, Japan and Asia are Electrical train sets. Chinese Railway is also running train sets for its overnight services with sleeper coaches. These train sets are highly energy efficient, faster, provide better comfort and generate line capacity. IR also need to adopt the latest technology (Distributed Powering) to cut down the running time for important prestigious Inter city trains for following reasons:

Improvement in Acceleration.

Acceleration plays a major role in achieving higher average speeds. This becomes very relevant when there are large number of speed restrictions and unscheduled halts and slowing of trains due to heavy congestion on the routes and differential speeds of the trains. Typical speed vs distance and speed vs time curves of loco hauled trains is given below

Technical_Paper_on_Train_sets_image1

Technical_Paper_on_Train_sets_image2

Deceleration of Loco hauled Trains

Loco hauled trains are provided with friction brakes which operate on lowering of air pressure in the brake pipe, which is a very slow process. It takes almost 25 to 30 seconds for the application of brakes in the last vehicle vis-a-vis first vehicle, due to which brakes have to be applied very gradually to avoid jerks to passengers. Brake release also similarly takes some time due to which train acceleration further slows down. Train deceleration is also around 0.2 m/s2:

Sl.No. Speed Restriction in kmph Time Loss in acceleration (Seconds) Time Loss in braking (Seconds) Time loss in acceleration and deceleration in seconds
1 Halt 72 144 216
2 15 63 126 189
3 30 54 108 162
4 50 42 84 126
5 60 39 72 111
6 80 27 48 75
7 100 15 24 39
8 120 3 6 9

 How Train set can help?

Operational Parameters of Train set vis-à-vis Loco hauled trains

Operational Characteristics Loco Hauled 21 coach Rajdhani Train Rajdhani run with EMU Train set
Acceleration (Starting) 0.22 m/s2 1.0 m/s2
Deceleration 0.20 m/s2 1.0 m/s2
Time to achieve 130 kmph 279 seconds 50.3 seconds
Distance required to travel to attain a speed of 130 kmph 6489 meters 1089.7 meters
Additional time required for acceleration and deceleration for a halt with maximum speed of 130 kmph 216 seconds 41 seconds

Technical_Paper_on_Train_sets_image3

 

Technical_Paper_on_Train_sets_image4

 

Reduction in run time between New Delhi and Howrah with Train sets

Speed Restrictions kmph Time Loss in Acceleration and deceleration Time saved by Train sets vis-a-vis Loco hauled train (Sec) No of speed restrictions Total time Saving with train sets(in sec)
  By Loco hauled trains (Seconds) By Train sets with acceleration and deceleration @ 1 m/s2 (Sec)
Halts 216 41 175 6 1050
10 198 36 162 6 972
20 180 30 150 13 1950
30 162 24 138 31 4278
40 144 20 124 6 744
50 126 16 110 6 660
60 111 13 98 4 392
70 93 10 83 19 1577
80 75 7 68 4 272
90 57 5 52 4 208
100 39 3 36 17 612
110 27 2 25 5 125
120 9 1 8 14 112
Total Time savings 135 12952

Savings in run time 216 minutes or 3 hours and 36 minutes

Simulated run of 21 coach Rajdhani Train with WAP7 Loco for 8 hours with Permanent Speed restrictions only

Run with Loco hauled conventional train

Run with Loco hauled conventional train

Simulated run with Desiro train sets with 1.0 m/s2 acceleration and 1.1 m/s2 deceleration with permanent speed restrictions alone

Run With Train set

Run With Train set

Due to large number of speed restrictions trains hardly achieve the maximum permissible speed of 130 kmph as can be seen from the simulated speed time curve of Howrah- New Delhi Rajdhani. Actual total time between HWH-New Delhi for 1440 km is 17 hours and 5 minutes, which can easily be done in 14 hours with Train sets, even with maximum permissible speed of 130 kmph i.e. without any expenditure on track and signaling infrastructure. A net savings of 3 hours in run time despite 135 speed restrictions.

Energy Efficiency

Train sets are highly energy efficient because of following reasons:

  • Propulsion equipment is mounted on the coaches, hence locomotives and Power cars in conventional loco hauled trains get eliminated. Weight of one Loco and two Power car is almost one third of the train weight, resulting in proportionate savings in energy consumption.
  • Improved aerodynamics compared with older trains (leads to about 25% less energy consumption).
  • Regenerative braking leads to substantial energy savings especially in Indian conditions with large number of speed restrictions requiring frequent braking (17 to 25% energy is recovered).
  • Savings in diesel fuel in power car.
  • Improved energy efficiency in power supply, partly due to more advanced technologies of the trains (3-7%).

Total energy savings with Train sets is more than 50%. As per UIC report even with increase in speeds, energy consumption per passenger comes down with train sets vis-à-vis Loco hauled trains. Rajdhani train consumes 34 thousand units of Electricity and 2000 litres of fuel for a run between New Delhi and Howrah. Savings in money terms per trip @ Rs 5 per unit for electricity and Diesel @ Rs 50 per litre works out to Rs 1.85 lakh per day or Rs 6.75 crore per annum.

Enhanced Safety

  • Regenerative and electro-pneumatic braking leads to higher deceleration and reduced emergency braking distance leading to enhanced safety
  • Reduced jerk rate and smoother braking and acceleration due to electro pneumatic braking vis-à-vis friction brakes in conventional trains
  • Train sets have automatic door closing leading to improved passenger safety
  • Micro processor based diagnostic and monitoring system further ensures safety vis-à-vis alarm chain based system, which has a slow response time
  • Modern Train sets are provided with Automatic train protection systems

Reduced maintenance of assets

  • Reduces wear and tear of the track due to elimination of locos and power cars with lighter coaches and distributed powering and tractive forces.
  • Train sets are equipped with the modern three-phase IGBT technology with fully suspended motors, which require very less maintenance.
  • Regenerative braking leads to reduced wear of brake blocks and tyres
  • Need for Maintenance facility for passenger locos is eliminated.

Improved reliability

  • Modern 3 phase technology is highly reliable
  • Distributed powering has lot of in built redundancy (50% to 60% axles are powered), which leads to very high reliability
  • On board diagnostic system reduces dependence on the skills of Pilots, further improving the reliability

Reduction in Pollution

  • Reduced noise pollution due to elimination of power cars and locomotive. It is very important as presently noise norms are being violated on these trains. Average noise levels exceed the maximum permissible 75 dBA level. Likely to cause hearing loss as per UN norms. Especially affected persons are power car staff and persons travelling in adjacent coaches.
  • Reduced carbon emissions and air pollution especially on the station platforms.

Improved Passenger comfort

Modern Train set cars are provided with ergonomic coach design and improved passenger comforts, with infotainment systems and air craft type mini pantry. Aerodynamic design of the nose, distributed powering and electrical braking helps in comfortable jerk free ride.

Improved throughput

  • Further with cabs at both ends, turn round time required at terminal stations is less than 15 minutes, leading to improved utilization. A train set running between New Delhi and Howrah can start From Kolkata at 7:00 pm and reach New Delhi at 9:00 AM and run an extra trip between New Delhi and Kalka and back between 9:00 AM and 7:00 PM.
  • Presently 21 car Rajdhani train has only 17 passenger coaches. With train sets Power cars and locomotive and even pantry car can get replaced by passenger coaches thereby increasing the throughput per train. Number of coaches can also be further increased to 24 passenger coaches thus helping in increased revenue and meeting the growing passenger demand.

Improvement in Line capacity

  • Faster acceleration and deceleration leads to reduction in time required to clear the critical section thus improving the line capacity on congested routes.
  • Higher carrying capacity of the trains will reduced the number of trains required for same through put.

Financial Returns

Capital Cost

Capital cost per car for trains sets running at maximum permissible speed of 140 kmph is around Rs 8 crore per car(Cost of Cars running on airport express having similar acceleration/deceleration characteristics) and a 21 car modern train set would cost Rs 175 crore, (which can be substantially reduced if manufactured indigenously or at RCF) vis-à-vis Rs 75 crore for a loco hauled 21 coach Rajdhani which has only 17 passenger coaches.

Operation and Maintenance Cost

Savings in O&M cost of Train sets vis-à-vis conventional Rajdhani trains will be Rs 5 crore per annum, mainly on account of savings in energy cost.

Passenger Revenue

Additional passenger revenue from train sets will be around Rs 20 crore per annum due to additional throughput due to replacement of power cars and loco by passenger earning coaches and additional trips due to reduction in run time.

IRR

From above it is seen that there will be additional net savings of Rs 25 crore per annum with an additional investment of only Rs 100 crore on one 21 car train set giving an IRR of more than 25%.

Way Forward for IR

There are following options available with IR for increasing the speed of trains running on existing tracks:

  1. Manufacture Train sets at RCF: Existing LHB coaches are fit to run at speeds up to 180 kmph. Three phase propulsion equipment can be mounted under slung on these coaches to convert them to distributed powered train sets. In this case, interiors of the trains will remain the same and IR can continue with existing Class of coaches (3AC, 2AC and FAC). The leading coach will be converted to driving car with suitable changes in the nose profile. This is the least cost option. Capital cost will only go up marginally with very high IRR.
  2. Import few Train sets through global tendering of modern design with comfortable interiors, air craft type pantry so that pantry car can be dispensed with and replaced by passenger coaches. The cost of imported train sets is around Rs 8 to 10 crore per car i.e. Rs 175 crore for a 21 car train set vis-à-vis Rs 75 crore for a conventional loco hauled 21 coach Rajdhani train with only 17 revenue earning passenger coaches. With reduction in run time, savings in fuel and energy cost, increase in passenger revenue, reduced maintenance costs and extra trips, it will be possible to achieve a very high IRR on Rajdhani, Shatabdi routes.
  3. Enter into an MOU with some government, for introduction of modern train set technology from that country for trials. Swedish Government and French government has shown keen ness for such an arrangement.
  4. Permit Private operators to operate Train sets on PPP basis who will be attracted by the high IRR

In view of numerous advantages of train sets, Indian Railways must introduce EMU Trains on select Shatabdi/Rajdhani routes as a trial measure for reducing the journey time without any up gradation in track and signaling system. An effort in this direction will herald a new era in operation of Rajdhani and Shatabdi trains. Further for achieving higher speeds, a train set is the only option. As and when the track is upgraded to 160 kmph, same train sets can be used by adding additional motor coaches.

With Modern Train sets, it will be possible to make journey between New Delhi and Howrah, a very comfortable overnight journey and provide the competitive edge to IR vis-à-vis Airlines.

Author: Rajeev K Bhatnagar

Rajeev Kishore Bhatnagar graduated in Electrical Engineering from IIT Delhi and joined Indian Railway Service of Electrical Engineers in 1978. He has very wide experience in diverse fields such as Research and Development in Electronics and Telecommunication, Software Development, Operation and Maintenance of Mumbai Suburban Services, Electric Locos, Train lighting and Air conditioning Services on Indian Railways. He has also worked as General Consultant to Delhi Metro for Phase-I and as Head of Strategic Business Unit at RITES, offering Project Management Consultancy to Electrical Construction Projects. He is presently working as Adviser Electrical(G), Railway Board in the Ministry of Railways, Government of India, responsible for major policy decisions regarding planning, procurement, maintenance and operations of Metro services, Suburban services, Rajdhani, Shatabdi, Mail/Express and Mainline EMU and passenger trains running over Indian Railway Network. He is also responsible for Technical planning and Safety of Rolling Stock for all Metros in India.

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There Are 5 Comments

  1. Shayak says:

    Sir

    Thank you very much for posting this informative article on the Forum. I was having a couple of queries regarding details of the braking strategy and the power requirements of the proposed trainset.

    In your simulations you have taken the deceleration of ordinary trains as 0.2 m/s^2 which is equivalent to 0.7 km/hr.s. However on several occasions on board WAP4 hauled Rajdhani Express I have observed the following procedure being employed by the LP for braking : when a caution for 30 is given at some mast, the LP cuts throttles 3 km before that mast and engages the brakes though without applying any braking power. 2 km before the caution, when the train is at 115-120 km/hr, the brakes are applied with great force to ensure a near-uniform deceleration to 30 km at the target mast. Using these figures, I am getting a time of 29 s to cover the first km and 48 s to cover the remaining two, thus amounting to a total of 77 s for the brake run. For acceleration, I am using the figures from my work on driving algorithms for WAP4; the time from 30 km/hr to 130 km/hr comes as 275 s and distance required is 7.3 km. Thus if the train decelerates from MPS to 30 km/hr and immediately accelerates again to MPS, a total of 275+77=352 s is required to cover 10.3 km. In the absence of the caution, this would have taken 287 s and thus I am getting an ER requirement of 65 s for the caution. Assuming this to be an underestimate I can increase to 90 s or even 100 s but the figure is still lower than the 162 s used in the simulations. And these figures are for WAP4 hauled train; I have never been on a WAP7 hauled train but the braking there is even steeper. As examples, in a recently documented run between CNB and MGS, the stretch from BEP to MNF took 17 min 40 s as against 13 min of WTT. There was a caution in the middle from mast 786/20 to 786/14 with 20 km/hr being the prescribed speed. Hence about 2.5 min were used in cautious crawl while 2 additional minutes were used in acceleration and deceleration. On the same run, stretch from GAE to PRE took 24 min 45 s as against 21 min of WTT. There was a caution in the middle from mast 749/26 to 748/26 with 30 km/hr being the prescribed speed. Once again, 2.5 min were used in cautious crawl and only 1.25 additional minute was used in acceleration and deceleration. These examples seem to indicate that aggressive braking might cause lower ER requirements than the ones used in the simulation.

    Secondly, your speed-time plots of the hypothetical EMU trainset indicate an acceleration from 120 to 130 km/hr in just 7 s. Assuming the train weight to be the same as that of a 21 coach LHB (which is 1020 tonnes), this requires a TE of about 370 kN. Moreover, using the LHB drag formula Frr=0.699+0.0215v+0.000345v^2, the drag on the train at 130 km/hr evaluates to 95 kN. Thus, achieving that acceleration at 130 km/hr requires a total TE of 465 kN, which amounts to a total power output exceeding 21000 HP. I am not very sure whether this is feasible or not. This would require installation of an enormous powerplant which would only be used at full capability for a very brief period (tail end of the acceleration run). By contrast, locos such as WAP4 and WAP7 operate at full power for a large part of the acceleration run (typically above 60 km/hr).

    Perhaps a more down to earth solution of reducing the journey time in NDLS-HWH section is to increase carrying capacity with construction of additional tracks and to reduce/remove permanent speed restrictions on the route. For example, CNB-MGS section carries extremely high traffic density (>300 passenger trains and >250 goods trains every day). Nevertheless this section is double track only, resulting in enormous congestion and consequent massive delays of Mail/Express/Superfast trains (as is apparent from tracking NTES on any given day at any time of the year). On the other hand, GZB-ALJN, MGS-DOS and SKG-DKAE are triple track while STN-SKG is quadruple track section. Construction of additional track in CNB-MGS will significantly improve speed and punctuality. Also, presence of goods trains at ALD and MGS causes huge detention at BMU, SFG and ALD home and again at ARW, JEP, BH K and MGS home. Construction of goods bypass as at CNB will aid the situation. It is because of this that even Rajdhani Express is allotted 42 min slack time in this section – the fastest Rajdhani (22812/24) goes CNB to MGS in 4 h 03 min while the WTT minimum running time is 3 h 21 min. Another problem, especially in DHN-HWH section is repeated permanent speed restrictions. Numerous cautions between DHN and ASN and subsequent cautions at ASN, RNG, UDL, BWN and SKG cause high run time of 3 h 10 min for Rajdhani in 259 km multiple-track section. The stations can be re-designed so as to keep a straight alignment of Through Line so that non-stopping trains may skip at MPS, as they do in DGR or KQR. I think that such changes in permanent way will be the easiest solution to improve speed and punctuality in NDLS-HWH section.

    I would be happy to receive your feedbacks on these suggestions; in case you want to reply privately you can contact me at [email protected] and [email protected] email addresses.

    • Mahesh Kumar Jain says:

      Thanks and I have advised the author to go through your comments

    • Shayak says:

      Corrigendum : I regret to announce an error in the original ER calculation for brake run. A factor of 2 had been missed out. The actual duration of brake run is 125 s and the ER requirement is 113 s. The error is regretted.

      Shayak

  2. Shayak says:

    Sir,

    I am having a further query here regarding the simulation graphs shown in the last two figures of this Article. From these graphs it appears that Rajdhani is reaching ALD at 8h 20m with a conventional loco and 7h 50m with the trainset. This amounts to a time gain of 30 minutes over more than half of the journey, and this gain cannot increase to 3 hours over the remaining distance. In fact the gain in ALD-NDLS will be rather small as sections ALD-CNB-TDL are almost free of permanent speed restrictions. Hence the graphs indicate a full-journey gain of less than 1 hour with the trainset, while the table says 3 hours. Maybe I have understood something wrongly and I would be very grateful if you could clarify this doubt.

    Sincerely,
    Shayak

  3. A. K. Mandal says:

    Superb platform for latest info & up-graded knowledge of IREE friends.

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