Monday, November 20, 2006

High Tech and Next Generation Passenger Rail

We have previously blogged the subject of Next Generation Passenger Rail and how high-tech control for locomotives and trains could be implimented.

The December issue of Trains carries an article about the recent federal mandate to convert to ECP braking. (Electronically Controlled Pneumatic braking)

On US trains on what is termed the "steam" railroads, the latest variation of the original Westinghouse air brake design from the late 19th Century is used. (Steam railroads are "heavy." They are not street railways, in general, and not light rail or rapid transit systems. However, many commuter railroads are steam railroads by this definition. Many rapid transit and street railroad systems also use regenerative braking, some use vacuum brakes and air brakes that are different from the Westinghouse system, and some use hydraulic brakes.)

With the US system, the brake pipe and air reservoirs on all cars are charged with compressed air produced by a compressor on the locomotive. Without going into exactly how this happens, we can say that a reduction in the pressure in the brake pipe going from car to car causes an application of the brakes. As this pressure reduction starts at the locomotive, it takes time to get to the last car of a long train.

ECP would add a control cable and control box to each car. A presumably digital signal would apply the brakes in all cars according to the brake application chosen by the engineer. Application for the whole train would be almost instantaneous and greatly assist in both control and stopping distance.

We think that anyone with an interest in railroading can see that this would take us one step closer to remote control of trains, with accompanying cost and safety improvements. (Some rapid transit trains are currently remote controlled. It is precisely because they use braking and power systems that offer better train control.)

ECP is an incremental change. ECP does not follow the policy of this blog, Revamp Nothing. ECP can be applied to existing systems without changing the entire system, and the cost can be spread out over the many owners of railroad rolling stock.

Following the informal guidelines of Revamp Nothing, a non-incremental change to a better form of ECP would allow for the following improvements: Either switch to vacuum brakes or allow for individual cars to charge their own reservoirs. Eliminate the cable and use digital (through the tracks). Let the train driver/engineer make one uniform application or apply brakes differently on different cars depending on conditions. Add regenerative (dynamic) braking on cars as it now exists on locomotives and on catenary systems.

Although Westinghouse had a good idea, pneumatic braking depends on not losing your air. The system has to be recharged. In vacuum braking, once you pull a vacuum, atmosphere does the work. And we think anyone who has ever operated a train or run a realistic simulator can see the advantages of being able to control where in the train you apply the brakes.

Comments anyone? We'd like to hear from the engineers.

© 2006 - C. A. Turek -
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