Not the CAT per se, but its over a couple exit ramps. One to the callahan tunnel and one that empties out to ground level on the next greenway parcel. You can follow the curve on maps.
Exit to ground level.
Then if you look at the right trench and imagine how youd exit right of the CAT and under this parcel then curve and line up to the tunnel you can see that too.
- - Edit, I just checked on maps and its actually shown on there too.

The yellow parts are uncovered roads. The tunnel on the left is in an open air trench and the top is the exit ramp. The green upside down triangle on the right is parcel 9.