For the first half of June, the University of Colorado A line averaged three trains a day with delays exceeding 15 minutes. That is about two percent of the daily average total of 143 trains. News reports indicate this performance level does not satisfy either the RTD Board or its general manager, Dave Genova. June 15 experienced the highest number of delayed trains: 19. Eight of the first 15 days of the month experience no defined delays. However, overall on-time performance declined from about 90 percent the first week of operation in April to about 80 percent. The A Line runs on 15-minute headways during peak hours. Only one of the delays in early June was attributable to a lightning strike. Neither RTD nor its concessionaire, Denver Transit Partners, has provided an explanation for the delays other than lack of full operational status of its cutting-edge positive train control system (PTC). Flaggers remain on-site at 11 at-grade crossings pending resolution of the PTC issues and implementation of the quiet zone for the 23-mile corridor.