Interesting that all the folks from out of the North East just can't fathom how it is in and around NYC. Things are different all over the country, even though you would like to think that the US is just one homogeneous entity.
When you drive large vehicles in the NJ/NYC area, you need to be aware of what you are doing. Not only are there many low clearances, those heights that are marked are not measured from the roadway to the obstruction. A 13' 6" semi will fit under a bridge signed 12' 10".
If that isn't confusing enough, the cash toll for the George Washington bridge can be over $100 and they don't want to accept $50s?
Now on the flip side of that, here in ND, you can legally drive farm equipment on the interstate. It may not fit under the bridges as the overpasses may only clear 13' 6", but all the non federal highways in this state have a statutory height of 15'.
