In addition, during periods of heavy ridership such as San Diego Comic-Con, Green Line trolley service between Gillespie Field and Santee was replaced with a shuttle.

The trolley also adds to congestion in the Santee area as the three-car trains (necessary on other sections of the line) operate with few passengers and stop traffic as they slowly traverse Cuyamaca Street.

[2][11] To address these issues, starting in the early 2020s, the MTS began planning to add a third track and extending a platform at the El Cajon Transit Center, to allow shuttle trains to terminate there.

[2][11] Although the promised June 20 public hearing was held, the MTS Board of Directors was prevented from approving the Copper Line because under federal law, a service equity analysis needed to be redone.

[16][14][17] In preparation for the opening of the Copper Line, the MTS made safety approvements to the El Cajon Transit Center, including the addition of new personnel, support staff, and signs.