I-25 is the major north/south interstate system.  Within the project area, I-25 is a rural, divided interstate with two 12-ft lanes in the northbound and southbound directions with 10-ft outside shoulders and 4-ft inside shoulders. US 380 consists of two 12-ft travel lanes with 8-ft wide shoulders as it approaches the nearby community of San Antonio to the east. 

The land surrounding the San Antonio interchange is primarily undeveloped and rural with little to no development directly adjacent to the interstate.  Businesses and homes can be found half a mile to the east in the community of San Antonio. The San Antonio Fire District is located directly east of the interchange on the south side of US 380. Cattle grazing and agriculture are the primary land uses in the vicinity of the study area.

Based on the study findings (see the Phase 1-A/B Report below), Alternative No. 3 was recommended to be advanced for further development. The interchange layout is modified to a tight diamond configuration with an adjustment of the US 380 alignment to the south to provide additional distance between the US 380 and Walnut Creek crossings. The improvements would correct the I-25 horizontal geometry, incorporate exit and entrance ramps that meet current design standards, replace the bridges at I-25/US 380 and I-25/Walnut Creek, and add drainage features to decrease erosion and scour.

This alternative would upgrade the interchange configuration to a more modern layout (diamond interchange) that meets user expectations, reduces temporary closures of US 380 during construction, and fulfills the purpose and need of the study by improving safety. A minimal amount of new right-of-way will be needed to accommodate the proposed improvements.