 With the proposal for the brand new Interstate 99 following U.S. Route 15 's alignment , construction was upgraded once again , and a new alignment for U.S. Route 15 was started in 2005 . The alignment was constructed for the final 5 miles ( 8 @.@ 0 km ) from Tioga to the state line . With the alignment 's completion , Route 15 was realigned onto the newly opened freeway on October 1 , 2008 . The entire project cost $ 102 million ( 2008 USD ) , including one new interchange and the completion of the Route 287 interchange in Tioga . 
