Are 10-car-long Rapid Transit trains possible?

A press release announcing the renovation of the CTA Red Line Clark & Divison subway station mentions extending the platform length to accommodate 10-car trains, as well as creating a new, accessible WEST entrance at LaSalle Street, which will be built first, before the East entrance at Clark Street is rebuilt.

That would seem to suggest that other some other CTA subway stations already have platforms that are long enough for 10-car trains.

I can see either the Brown, Blue or Red Line using 10-car trains at some point.

And I thought I remembered reading brochures c. 1940's and 1950's about the construction of the two subways which said the platforms, as originally built, could handle 10-car trains. But maybe they meant "with only inches to spare" as opposed to having extra "wiggle room".

Has the CTA EVER mentioned accommodating 10-car trains before?

P231: My Uncle was a CTA Motorman from 1958 retiring in 1986 and I recall that the thought to operate longer trains
was looked into by the CTA...

There are definitely stations-like in both Downtown subways-that can easily accommodate 10 car trains...

The Howard-Dan Ryan Red Line would be my first choice for 10 car trains...

This is a question that I believe Graham Garfield at http://www.chicago-l.org can answer in depth because of his
knowledge of the CTA system...

MACTRAXX

I believe 10 car trains on the CTA are very possible, A number of CTA stations on the blue line where built to extended lengths back in the day, which could easily hold 10 or even 12 car trains. However the question becomes does the blue line even need 10 car trains now a days? back in the 50,60s the demand was there however the west side of chicago is so depopulated I think 6 car trains would be acceptable for the west side runs ( 8 cars need for downtown to Ohare). I do believe the red line stations were built hold 9-10 cars ( for leeway of an 8 car train stopping distance ) but thats just barely, so red line stations would need to be extended. It's funny how time changes things, The red line during peek now needs 10 cars trains but the stations out side the downtown area currently don't support it, and the blue line stations can easily accept 10 cars however really don't need it on the west side.

One more issue that would need to be addressed is would there be a need to bring back separate conductors if 10 car trains were put into service, back in the 90s CTA got rid of them and said that 8 car CTA trains were just long enough that the engineer could perform the conductors roll from the front of the train. with a 10 car trains extra length would CTA still consider that safe for one man operation. Just more more thing to think about.