Timeline
Work on Phase 2 started in August 2019 and is expected to be complete in mid 2022.
The eastbound SH 151 to southbound Loop 410 flyover opened on September 15, 2021.
The northbound Loop 410 to westbound SH 151 flyover opened on October 9th, 2021.
Future projects to complete the remainder of the SH 151/Loop 410 interchange are currently unfunded and therefore have no timeline.

Description
Phase 1 of this $81.8 million project constructed the first two flyovers at the interchange at Loop 410 and SH 151, widened Loop 410 to eight lanes from Ingram to SH 151, and made various ramp improvements on Loop 410 and on SH 151.

Phase 2 will build the eastbound SH 151 to southbound Loop 410 and northbound Loop 410 to westbound SH 151 flyovers. This project will also widen Loop 410 to ten lanes from Ingram to SH 151 and to eight lanes from SH 151 to US 90.

How this project will help
The additional flyovers at the Loop 410/SH 151 interchange will improve operations and reduce congestion in the interchange and adjacent access roads. The additional lanes on Loop 410 should accommodate expected future traffic volumes.

FAQ

• Why is construction starting again less than a year after the first phase was completed and before the work south of SH 151 is done?
  This is because TxDOT's funding was increased significantly a few years ago, so backlogged projects are getting funded much sooner than expected. Phase 2 of this project is one of those backlogged projects that has been expedited due to the new funding; it was originally expected there would be five or more years between phases.
  
  
• Why did work stop for so long on the flyovers in Phase 1?
  After work had started, an engineering error was discovered in the plans for the long steel beams which delayed their fabrication. In the meantime, in order to prevent the overall project from being delayed, the contractor worked on other areas of the project out-of-sequence, i.e. work that was scheduled to be done after the flyovers were completed was expedited. Therefore, while this issue did delay the opening of the flyovers, it did not cause any delay in the overall completion date of the project.
  

Schematic
Click on the image below to open the detailed schematic for this project (Phase 2) from TxDOT with my own annotations added to help clarify and explain the various elements. The schematic will open in a new window that you can scroll and zoom. 

DETAILED PROJECT SCHEMATIC

TxDOT - I-410SW from SH 16 to Ingram Road https://www.txdot.gov/inside-txdot/get-involved/about/hearings-meetings/san-antonio/030519.html