Chicagopcclcars- I agree with the Bombardier MITRAC propulsion being loud. I have had a chance to ride the CAF 5000 series trains with MITRAC propulsion and also the Alstom rebuilt 2000/3000 and new 6000 series trains with Alstom ONIX propulsion in Washington (all rebuilt or new trains from Alstom use identical motors.) Here's an interior ride comparison:
Bombardier MITRAC:
http://www.youtube.com/watch?v=_lpalny2 ... re=related
Alstom ONIX:
http://www.youtube.com/watch?v=wh5putr9 ... re=related
My own personal experience- the MITRAC equipped trains are definitely louder but not the loudest on the interior in that system. However in DC, both the MITRAC and ONIX equipped trains both are known for providing a very smooth ride on the rails and are comparable to each other.
In Bombardier's defense, their MITRAC propulsion is quieter than the AdTranz motors which they replaced (the 1507/1508 series that are used in San Francisco [Rohr A-car rehab], New York City [R142A/S, R143], Atlanta [all trains across the CQ310,311,312 series], and Boston [Breda Type 8 LRV trains] built in the late 90's/early 2000's.)
What does this mean for the Chicago? The MITRAC propulsion provides a very smooth ride and think that it will be an improvement over what is used currently. The big question on the interior of the trains is how much sound deadening material will be used to limit the amount of motor noise being heard? That remains to be seen.
Gotta love Alstom. Every year on opening day of hunting season, it is a paid holiday!