http://dallashorseshoe.com/photos/
Isn't the I-35 northbound bridge that veers left after crossing the "lake" and over I-30 relatively new? They are building its replacement right next to it, but I thought the original bridge was just redone. As a matter of fact, wasn't that long ago they added a HOV lane to it.
Yes, that northbound structure north of the river is quite new. I have photos of the area from October 2007 and the old structure is still there, with no construction underway. I remember the construction as being recent, and I'm thinking that the new northbound structure is less than five years old.
I never saw any news reports about why that structure was replaced. I speculated that maybe the old bridge had structural issues. Or since they needed to build a new structure for the HOV lane, it was affordable and made sense to go ahead and also replace the main lane bridge. Whatever the reason, I assume they did not anticipate that the Horseshoe project would begin in 2013.
The NB I-35E mainline bridge over I-30 was built in 2001ish, based on historical imagery in Google Earth. With only 2 mainlines+1 (reversible) HOV, it's pretty underpowered for the traffic volume through there. I believe the new bridge adds an extra lane. Most likely the old one is going away due to space/clearance issues, as a lot of new lanes are being built in a fairly tight space.
Looked at the latest pics of the construction site, I did not know the original I-35 southbound bridge across the lake was demolished. I know the northbound lane original bridge was demolished about a month ago.