A temporary bus service from Olde Town Arvada to Union Station will start this Sunday.
The new 55S route looks like this:
And it's temporary because the G Line was supposed to be moving people between Arvada and Union Station by now. However, RTD pushed back the opening of the G Line until 2017 because of the same crossing gate problems that currently plague the A Line.
The 55S will depart every 60 minutes from both Union Station and the Olde Town Arvada Park-n-Ride. The 55L, which provides rush service between Olde Town and Union Station, remains unaffected and will continue to operate as usual.
Schedules and more information available here.