Route 103 travels on Fredericksburg Road and Zarzamora Street from Crossroads Park & Ride to the Madla Transit Center.

Discounted fares are available to students, children 5–11, seniors, active-duty military, and people with disabilities.

The route begins at the Ellis Alley Park & Ride on the eastern fringe of downtown San Antonio.

Route 100 has six stations along Fredericksburg Road, including a stop at Wonderland of the Americas in Balcones Heights.

[8] Route 103 runs along Zarzamora Street from the Crossroads Park & Ride, near Wonderland of the Americas, to the Madla Transit Center, near Interstate 35.

[13] The planning process for bus rapid transit service in San Antonio began in September 2002.

[14] While Primo was originally set to include dedicated lanes for buses, VIA settled on mixed traffic operation before submitting the required environmental studies.

[16] VIA staged a free preview of Primo on December 15, 2012, and launched regular service two days later.

[19] In September 2015, VIA announced plans to expand Primo service to the Military Drive and Zarzamora Street corridors.

[21] On April 6, VIA shifted weekday service to Saturday schedules, reducing frequency on all Primo routes to 15-minute headways.

[24] Primo launched with 16 60-foot (18 m) articulated buses fueled using compressed natural gas (CNG).

[7] These buses come with free WiFi, two wheelchair positions, and space for three bicycles in the rear of the vehicle.