Talk:Four Level Interchange

Project Engineer?
A marker for Sam Helwer on the Redwood Highway in Northern California states:

"By the 1940's he was Project Engineer for the world's first four-level freeway interchange in Los Angeles; and became nationally recognized as State expert on freeway interchange design."

Reference http://www.hmdb.org/marker.asp?marker=1558

While this could refer to a different interchange, "world's first" should be unique. Can this be verified?

Charles Keith (talk) 18:59, 14 June 2011 (UTC)