Here's the story that I got from Brian who actually works on those lights (and sent me some parts, along with one of the old Seattle Marbelite traffic signals. I think you might recognize the signal from Western and Madison.)
Old Town / Pioneer Square is supposed to have original light standards. Naturally the guts have been upgraded. There was a big hullabaloo a few months back when a truck took down one of the standards and they wanted to make sure that it remained serviceable.
The pergola was knocked down (or at least one end of it was) by a truck years back and rather truck proof replacement parts were cast - resembling the original poles but like 4 times as thick. Ironically the ballard at 1st and Yessler that looks as if it was there to protect the pergola is simply lag bolted to the concrete.
I would have loved to have seen the old Form 109s when they were in service on the taller poles.