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San Antonio Area Freeway System
Interchange Flyover Heights

This page last updated February 1, 2024
US 281/Loop 1604 interchange

US 281/Loop 1604 interchange
(Photo source: Google Maps)

One question I get with some regularity regards the height of local interchange flyovers. Texas is notable in that the state builds spectacularly tall interchange flyovers, and their height is often a topic of curiosity. San Antonio was a bit of a latecomer to the high-flying interchange party, with the first modern "Texas-style" stack interchanges starting to rise from the ground here in the first decade of this century. Prior to that, the tallest interchanges here topped out at about 65 feet. But there are now five interchanges that have at least one flyover that's 80 feet tall or higher, and two more under construction will have flyovers at least 120 feet tall, which will be the tallest in the area and among the tallest in the state.

Given that, I thought it was time to compile a list of the tallest interchange flyovers in San Antonio.



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Methodology

Determining the height of a particular flyover is not as easy as it may seem. Both the structure itself, as well as the ground below it, are not level, with elevations varying continuously across the length. On curves, banking will cause a significant variation in elevation laterally across the bridge deck. And on the ground, besides the varying terrain, one big question arises: should the extra height that a depressed roadway adds be included in the calculation?

So for my calculations, I used the following rules:


Tallest interchange flyovers in San Antonio

The following table lists all flyovers in San Antonio over 80 feet tall, with the height at the highest point on the flyover shown. The table is sorted to keep all the flyovers in each interchange together with the interchanges ranked by their tallest flyover.

As mentioned above, if a flyover crosses over a depressed section of roadway, one height will be shown for the highest point over the depressed road, and one for the highest point over normal ground level along an adjacent roadway. Locations over a depressed roadway are marked with an asterisk (*).

INTERCHANGE CONNECTOR HEIGHT
  EB 1604 to WB 10
Near center of interchange
to lower level access roads
(Under construction)
125'
WB 1604 to EB 10
Near center of interchange
to lower level access roads
(Under construction)
125'
 
East
WB to SB
Over EB 10 mainlanes
(Under construction)
120'
  WB to SB
Over NB 281 mainlanes*
Over eastern turnaround

109'
87'
EB to NB
Over SB 281 mainlanes*
Over SB access road

100'
84'
  EB to NB
Over SB access road*
Over SB 410 mainlanes

93'
87'
  EB to NB
Over WB access road
88'
EB to SB
North of Halm Blvd.
85'
WB to SB
Over EB 410 mainlanes.
81'
  SB to WB
Over NW cloverleaf
88'
 
Northwest
EB 10 to EB 410
Over WB 410 mainlanes and access road
85'
WB 410 to EB 10
Over EB access road
82'
* Location over depressed roadway

Here are a few other interchanges that may be of interest:

The I‑35 NEX project will also have some tall flyovers; however, as a design-build project, the plans were not available, so I don't have height information on them yet.