There was a bridge, one lane was closed, the other lane was open.   There were barrels with flashing orange light in the closed lane.  They were redoing the bridge, one lane at a time.   Those barrels were sitting on rebar.  The bridge wasn't wide enough for them to put a concrete barrier between the good lane and the construction lane;  just a lot of 10mph signs (or whatever the speed was), etc.    It was dusk, I was on my 10-speed.  And there was just enough room next to those barrels in the missing lane for a bike rider staying to the right side of the lane.
Funny thing about rebar - the way it's criss-crossed, it easily stops the wheels of a 10-speed from passing through.  But, those holes are big enough for feet to go through.