These are on I-35W south of Fort Worth. Some people refer to them as Burlesson, but I understand they are in Alvarado City Limits. My friend lives about a mile away and send me this video.
According to supercharge.info there are no superchargers under construction in Texas and six SC locations that are currently permitted. The SC map on Tesla's site shows an additional 17 SC sites to be opened by end of 2018 (if I counted correctly).
Which site do you expect to actually begin...