added in September 2007. In September 2008, an additional train was added to the line, bringing the total number to four round trips in the peak direction. On May 31, 2008, service to Mukilteo station began. There are currently three stops along the N Line: Edmonds, Mukilteo, and Everett. Additionally, Sound Transit partners with Amtrak Cascades to allow Sounder riders to use the two trains per day that Amtrak Cascades operates to Bellingham, WA and Vancouver, BC through the RailPlus program. This allows commuters to use the Sounder fare structure between Everett and Seattle. The program is available only to riders who use monthly passes. The Amtrak Cascades trains do not stop at Mukilteo nor does Amtrak's Empire Builder from Chicago, Illinois. Weekday ridership on the N Line was roughly 1,100 in 2010 and was about 1,561 in the first quarter of 2016. Trains on the N Line have been prone to frequent cancellation due to mudslides throughout its history, though WSDOT has begun construction to remedy the problem. Future expansion Sound Transit plans to add additional S Line stations at Tillicum and DuPont. The track has already been constructed by Sound Transit with funding from WSDOT as part of the Point Defiance Bypass project. Funding for constructing the two stations was approved in the 2016 Sound Transit 3 ballot measure and is expected to cost $300 million. It was originally scheduled to open in 2036, but was delayed to 2045 due to a systemwide funding gap caused by increased planning costs. The Tillicum station is planned to be located near the intersection of Interstate 5 and Berkeley Street Southwest, adjacent to Joint Base Lewis–McChord. The terminus at DuPont station is planned to be located adjacent to an existing park and ride lot at Interstate 5 and Center Drive. In addition, Sound Transit plans to extend station platform lengths on the S Line to accommodate trains up to ten cars in length, up from the current seven, and increase service. Both programs were included in the Sound Transit 3 ballot measure and were originally scheduled to be fully completed by 2036, but were also delayed by the systemwide funding gap and subsequent realignment of projects. Platform extensions are scheduled to be complete by 2036, while additional trips on the S Line are scheduled to be implemented by 2046. Fares As with Link light rail, Sounder operates using a proof-of-payment fare