CTA Tattler

Lately a lot of people have been suggesting that the C.T.A. use solar or wind energy to power the system.Would it be enough,especially during unfavorable weather conditions?And wouldn't junior curmudgeons protest even the best designs on aesthetic grounds?For me the best hope would be geo thermal energy.

Converting the C.T.A. to geo thermal energy would be tailor made for the Obama stimulus program.

I'd be curious how much could be saved and how feasible it would be to do so. I know they are doing some of this at their bus barns and offices, which is very cool. They can never switch completely probably, but even 50% would be nice.

I've never understood why the CTA uses rheostatic dynamic braking instead of regenerative dynamic braking on the L trains.
Feed the power back into the trolley rail for the other trains to use instead of burning it off as heat under the cars.

UCC -

I suppose that it is done that way because that is the way the current system is designed. It is my understanding that the new rail cars are supposed to be able to be easily converted to a/c power and allow for regenerative braking. Right now, the third rail is 600 volts d/c and Chicago is the only major city in the world that uses such a system.

"Right now, the third rail is 600 volts d/c and Chicago is the only major city in the world that uses such a system"

Uhh...except for Boston, New York, Baltimore, Washington, Philadelphia, Pittsburgh, ......

The third rail is DC, and always will be, as it is in other cities. What is changing with the new batch of cars is that they will convert that to AC on board and use AC propulsion.

As to why regenerative braking isn't used, not sure. Perhaps it wasn't viable/extant back in the early 90s when the last batch of cars were purchased.

Class 1 railroads were using regenerative braking decades ago.
The CTA has so many trains braking at the same time it has other accelerating, it's just wasteful to burn the power generated by the brakes off into resistors under the cars, creating heat that has to be blown out with fans, using more power & creating a greater need for A/C in the summer.

Perhaps "viable" is the key word then. Class 1 railroads might have been able to afford locomotives with regenerative braking because they have a lot fewer of them than the CTA has railcars, which each have their own propulsion systems.

CTA trains probably don't use regenerative breaking because they have no capacity to store the energy within the trains limited on-board energy storage, and no capacity within the system to handle any backfed DC from the trains to the rails.

It would be interesting to design a train that could use regenerative breaking to capture part of the power currently wasted in breaking.

I would love to see the building of a solar power station on CTA grounds to assist in powering the train lines. Use solar as available, and utility to supplement, much as I do with an off the shelf inverter in my home now. Feed the power in at the same points it is currently so that the capacity to shut the power off remains unchanged. It could be a big marketing plus for the CTA as well.

If they were to do it, it would be a big project, heck, I would donate the funds for the first couple of panels, and I would bet they could get a lot of other people to help out as well.