text: https://wiki.openstreetmap.org/wiki/Key:tunnel says "In general, if the lower way is long and surrounded by earth it is almost certainly a tunnel; and if the lower way is short and the upper way is supported on concrete, brick on metal pillars / beams then that is almost certainly a bridge." So I would argue that this qualifies as a tunnel since University Ave is lower than the surrounding area. Also the crossings for Alma, Caltrain, and the bus loop are all connected and at the same level, so they're certainly not separate bridges.