1. Graeme Phillips IET Young Members Best Paper Competition 2011

2.  Relative advantages of electric multiple units and locomotives  Metro rolling stock  Suburban/commuter/ regional rolling stock  Intercity rolling stock  High-speed rolling stock  Conclusions

3.  System flexibility for short-term arrangements, e.g. Dutch Fyra service  Intermediate carriages can have reduced axle loads: - AGV duplex variant not yet feasible  Easy to change broken-down locomotives  Traction noise and vibrations attenuated before reaching carriages  Fewer motors to maintain

4.  Usable space in place of powercars  Higher accelerations possible  Potentially less total motor noise  Energy recovery from regenerative braking  Potentially less track damage, as weight is spread out more evenly  Noisy 373, 18 carriages and 2 locomotives, 395 6 motored carriages

5.  Space for other equipment: - savings if need to source unusually small parts avoided  Reduced rotational inertia inefficiencies (can be equivalent to about 13% of train’s weight)  Increased efficiency if characteristics can be achieved with fewer motors  Fewer motors to maintain  Reduced weight

6.  Can use lower-rated motors: - 09TS is 75% with 75kW motors, S Stock has 100% 65kW  Distributed tractive effort means better acceleration within adhesion limit possible  100% avoids need for additional designs  Increased regeneration  Increased redundancy

7.  Frequent stops → high acceleration needed  Fewer stops → lower acceleration feasible  Useful also with frequent speed limit changes  Variable even with similar train types: - influences optimal configuration

8.  300km/h operating speed  391km long  4 stations

9.  300km/h operating speed  301km long  21 stations

10.  EMUs with LUL in 1930s, rising since then  Variable even within family, e.g. Bombardier’s Movia: - 09TS has 75% and S Stock 100%  Can be seen with RATP: - MF 67 had M-T-M and M-T-M-T-M, but MF 2000 has 100%  Most above 50% today

11.  Most use EMUs at present, though some use locomotive arrangements, e.g. Graz S-Bahn  Spain’s Cercanías services 50% or above  SE, D, A and CH tending towards EMUs, e.g. FLIRT, Talent and Regina

12.  Also tending towards EMUs, e.g. Germany’s ICx ( ~ 50%) and UK’s IEP programmes  ÖBB chose Viaggio Comfort coaches for its Taurus locomotives for RailJet services  NS HiSpeed uses TRAXX locomotives as a temporary arrangement for its FYRA service

13.  Shinkansen & CRH trains all EMUs  Last of the four train types to shift to EMU  Talgo and Alstom still produce powercars  SNCF and ONCF recently ordered TGVs  50% common, e.g. Velaros, Zefiros etc

14.  Unusual bogie configurations can affect number of bogies per carriage and carriage length, so comparison is difficult  Talgo uses articulated monoaxle bogies  Copenhagen S-Tog uses single-axle system  Semi-articulation becoming common  Jacobs bogie most common

15.  Jacobs bogies traditionally unmotored  AGVs (100%) and FLIRTs use motored ones  Typical high-speed 200m 8-car EMU might have 16 motored and 16 trailer bogies  11-car AGV is 200m long and has 12 bogies  Fewer axles necessitate higher proportions

16.  Two independent monoaxles on each side  Used in trams, but rarely trains: - forced steering needed; no longitudinal creep forces  200m S-102 locomotive-driven with 17 bogies: - 4 dual-axle motored, 13 motored  200m AVRIL to have 17 bogies: - 6 dual-axle motored and 11 trailer monoaxle  Always unmotored  Short carriages

17.  10 single-axle bogies on 84m 8-car Litra SA  Semi-articulated and with 8 motored axles  Design chosen to reduce train weight  Carriages very wide (3.6m) and short  Number of axles lower than 100m 4-car train (16 axles/100m vs. 12)  Fewer axles means more motored ones needed

18.  Difficult to make conclusions  Fewer bogies means more need to be motored to get similar tractive effort  Fewer bogies may result in shorter carriages  Exceptions can have effects across system  Wider carriages possible

19.  Most modern metro trains use 2/3 or more motored axles on account of frequent stops  Easier to gain characteristics without 100%  Higher acceleration not always desirable: - LU’s allowable maximum is 1.5m/s ²

20.  100% not always desirable: - higher maintenance and weight (lowering efficiency)  Commonality of carriage types brings savings: - 1/8 motored undesirable, but 2/8 ok  High optimum figure if good recovery: - poor for DC, but can use inverting transformers or AC (Delhi uses 25kV 50Hz)

21.  Depends on service requirements  May be no need for high acceleration if few stops and padded timetables and so locomotives may easily fulfil needs  Congested routes with frequent stops and less padding will require greater acceleration

22.  Last train category to drift away from locomotives  50% very common for current and future designs (e.g. Velaro, Oaris, Zefiro etc)  More used if frequent stops required, e.g. BR 395s (2/3) & Shinkansen (50-100%)

23.  No single answer: - optimum combination depends on many different factors, e.g. gearing ratio, adhesion, stops etc  Depends on system trains run on  2/3 normal minimum for many modern metros; other train types can cope with less