ok, so who's building one of these for the layout?

I remember riding through Holland Tunnel as a kid but never saw that!  Then again the byline is before my time.

Not I, at this time.  

I never saw that either. It's effectiveness now would be moot. There is too much traffic 24/7 in all NYC tunnels now!

Between 1948 and 1959 we made around 8 round-trips though the Holland Tunnel each year. I may have seen one of these sitting empty, but certainly not manned and moving.

Great Job.  Breath the automobile and diesel exhaust all day.

The Port Authority used them into the 1950's until they figured out that the carbon monoxide was making the cops sick.

Wow! I remember seeing these when I was a kid, but never in operation. I recall thinking that they were cool.  Of course, anything on rails was cool to me then and still is now.

Proves there is a prototype for everything.

Chris S.