One specification that is causing some difficulty is the HSR train requirement for a floor height of above the rails. This is the international standard for high-speed rail trains, but Caltrain trains have a floor height of only . (Metrolink trains have a similar issue.) In October 2014, Caltrain and the Authority agreed to work together to try to implement "level-boarding" on the shared station platforms. The Authority resisted lowering their trainset floor height, but a solution was found with Caltrain's new Stadler KISS EMUs which will feature doors at two heights, with the higher doors compatible with the CHSR platforms.