I-680 Contra Costa Express Lanes Now Open

Last spring we asked about the impending I-680 express lanes running from Alamo to Dublin and it’s now open and in-effect from 5am – 8pm on weekdays. It’s free for carpools and qualifying clean-air vehicles but a new FasTrak Flex toll tag is required for high occupancy vehicles in which the number of passengers can be set. For solo drivers it will be possible to pay a toll which changes based on traffic conditions. Check out the I-680 express lanes information sheet here. Has anyone had a chance to use the new system? Does it help with traffic? Or does it feel like an additional tax ?