Auckland Harbour Bridge Barrier Movers

We didn't take the photo (Wikipedia) but saw this amazing machine in action sliding the cement barriers from one lane to another as we drove over the bridge.

What a way to adjust the number of lanes in each direction for the morning and evening rush hours!

Look up "barrier transfer machines" or "zipper machines." We learned to our surprise that they are also in use in Montreal, New York, Philadelphia, and San Francisco, among other world cities.