World's Fastest Train
Copyright ©2010 by Paul Niquette. All rights reserved.
On April 3, 2007, headlines all over the world heralded the World's Fastest Train, the V150, a special consist built by a partnership between Alstom Réseau Ferré de France and Société Nationale des Chemins de fer Français. The V150 set a new world record of 574.8 kph (357.0 mph) on an isolated section of trackway between Strasbourg and Paris, as recorded in this video.  The photograph below shows the V150 exhibited aboard a barge on La Seine...

...with some nearby tower in the background. "V150" was the code name signifying its targeted speed of 150 m/s. That achievement was marked about two minutes into the video, and the train continued to accelerate, reaching a peak of 159.7 m/s (~175 yards per second).  Think of a couple of football fields passing your train window at your resting heart-rate..

The previous record was 515.3 kph (320.1 mph), set in 1990 by an Alstom Train à Grande Vitesse (TGV). The V150 presages the successor to the TGV, which will be called Automotrice à Grande Vitesse (AGV).  Whereas the TGV configuration is equipped with powered cars at the opposite ends of each consist and unpowered passenger cars in between, the AGV uses self-propelled vehicles, all producing tractive effort from the overhead lines delivered to axles throughout the train.  Passenger seating aboard the AGV will be on two levels (duplex), thereby doubling the AGV's capacity without lengthening the TGV's stations and platforms. 

The World's Fastest Train draws 19.6 megawatts of electrical power and develops a total of 26,300 horsepower.  Special attributes of the V150 include [1] synchronous, permanent-magnet traction motors; [2] actively controlled pantograph; [3] enlarged wheel diameter by 19% to limit the rotational speed of the powertrain (5,688 vs 8,533 rpm); and [4] aerodynamic improvements -- [a] air dam, [b] flush-mounted windshield, [c] rigid membranes filling the space between cars, [d] roof fairings over the forward pantograph opening -- all resulting in a 15% savings in drag.

Whereas pictures of high-speed trains invariably feature their streamlined designs from the front, it is the rear of a body moving through a fluid that determines aerodynamic drag more than the front, with the familiar tear-drop shape being most ideal.  Passenger trains must travel in either direction, so their shapes are necessarily symmetrical.  Those red lights in the picture on the right indicate that our view is from the rear of the V150, with 'clam-shells' closed over its unused coupler.  We also see the pantograph on the rear car, which captures the electric power for distribution to traction motors throughout the train.

The V150's record-setting runs were conducted on a customized test-track [a] 88 miles long at a location chosen for favorable vertical profile, [b] long-radius curves with [c] superelevation set higher than standard, [d] catenary voltages increased 24% to 31 kVac (over standard 25 kVac), and [e] messenger wire tension pulled tighter than normal by 60% for mechanical stability. 

Solvers of two other puzzles, Station Stop and Trip Time, have taken into consideration many parameters that limit the speed of a train between stations in a commuter rail environment.  For high-speed rail travel applying the World's Fastest Train, let us simplify and idealize the seven most pertinent parameters... 

  1. Maximum Train Velocity ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ vMAX  = 357 mph
  2. Maximum Propulsive Power ~~~~~~~~~~~~~~~~~~~ pMAX  = 26,300 horsepower
  3. Maximum Tractive Effort ~~~~~~~~~~~~~~~~~~~~~~ eMAX = 27,600 pounds-force
  4. Maximum Train Weight ~~~~~~~~~~~~~~~ wMAX= 100 tons = 200,000 pounds-force
  5. Maximum Acceleration ~~~~ aMAX = 0.1 g = 2.2 mph/sec (limited by passenger comfort)
  6. Maximum Braking Deceleration ~~~  - aMAX = - 0.1 g = - 2.2 mph/sec (service brake-rate)
  7. Station Dwell Time ~~~~~~~~~~~~~~~~~~~ tDWELL = 5 minutes (enroute railway station)
A typical distance between stations in high-speed train service can be as short as a few miles or more than 100 miles.  For example, the planned California High Speed Rail project has eight intermediate stations between Sacramento and Los Angeles along a route 412 miles in length.  The segments range from 13 miles to 113 miles, with the average being 412 / 9 =  46 miles.  At its record-setting speed of 357 mph, a V150-class train could theoretically complete the trip non-stop in about 1:09. 
What would be your estimated overall speed for the same trip, making stops as indicated in the table below?
 
Intermediate
Stations
{a}
mph
{b}
mph
{c}
mph
{d}
mph
0
357
357
357
357
1
333
310
321
 
2
312
275
292
 
3
293
246
268
 
4
277
223
247
 
5
262
204
229
 
6
249
188
214
 
7
237
174
201
 
8
227
162
189
 
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