This is very unusual and interesting. I-35E has been widened so much that the former SB frontage road is now (at least temporarily) the northbound frontage road. When you get up to the lake bridge, the frontage road continues in a temporary configuration by entering the former southbound lanes on a former exit ramp, and crosses the lake bridge in the former left southbound lane.
Also of note, between Eagle Point Rd and Copperas Branch Park, the entire former highway (both north and southbound) is closed for now, which looks cool
Northbound on the former southbound frontage road, entering the freeway on the former exit ramp:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi1209.photobucket.com%2Falbums%2Fcc395%2FBrian5561%2F9.21.2016%2520002_zpseh9hvrix.jpg&hash=b8609d7eb3a8325d4867af3fe2fa19b6d22aae28) (http://s1209.photobucket.com/user/Brian5561/media/9.21.2016%20002_zpseh9hvrix.jpg.html)
Approaching the lake bridge in the former southbound left lane:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fi1209.photobucket.com%2Falbums%2Fcc395%2FBrian5561%2F9.21.2016%2520003_zpsmsqwd4lm.jpg&hash=503f358c4f50bc295f6843b8f99c4488157fb000) (http://s1209.photobucket.com/user/Brian5561/media/9.21.2016%20003_zpsmsqwd4lm.jpg.html)