Interesting how many times the lights were changed out. I think most of the old RIDOT poles left here origionally had 400 MV remote ballast clamshells (mostly Form 109 and OV-20) and teardrops, then around the 60's 400W MV cobraheads (M-400 and OV-25), and now 250W HPS M-250R2. Now the old poles are being replaced by tall davits with 400W HPS M-400 FCO on the freeway and shorter davits (same height as the old poles) with 250W HPS M-400 FCO.
Also interesting that the bottom of the bridge is concrete as well. Here you can see the metal "framework" underneath usually painted green and sometimes light blue.

Yeah, I forgot to mention that the 401 originally used 400w MV clamshells in the 1950s above too...the mercury trusses only came when the express-collector system was put in during the 60s.

As for the bridge, yeah most of ours are concrete bottomed but I've noticed some older ones have grey or green painted steel I beams and girders underneath. Something interesting about bridges here is that our bridge decks are always surfaced with asphalt, even if the freeway is concrete.

Different construction methods. Steel girder construction is quick and fast to erect, but has a limited life and needs regular maintenance. They are repainted every 5 years and will need replacing and major overhaul at around the 50 year mark. Cast concrete will last easily 2 centuries with minimal maintenance, but is more expensive initially, and needs either a casting yard at one end for cantilever launched units or the ability to have the underside scaffolded for months for cast in situ units. Mostly the steel bridges were either over railways or had rail on them, while concrete is the norm for motor traffic only bridges.

Here the freeways are asphalt but the new bridge decks are cement though older bridges have an asphalt deck.

I found a MTO document recently about the 401's lighting system and it turns out the truss poles originally had Powerlite B2215s with 400w clear mercs over the express lanes and B2213s with 700w clear mercs over the collector lanes. The ramps were 400w B2215s though.

Interesting. Here i believe 400W MV cobraheads were used on both the actual freeway as well as on the ramps. When the HPS take-over happened, 250W HPS M-250R2s were used on both the freeways and ramps. With new upgrades, it seems 250 watts isn't enough for RIDOT lol. It's now 400W on the freeway and 250W on the ramps. I guess now the NGrid is back to Cooper, the new FCO M-400s on davit poles will not be installed anymore. It'll be Cooper OVFs on the tall davit poles like it was back when RIDOT first began upgrading its lights.

The funny thing is, where OVFs were used, nearly half of them were replaced by M-400 FCOs over the past 7-ish years. I'll never understand why NGrid "second-in-line" is Cooper from GE. Ironically NGrid turns to Cooper when GE goes through quality issues. AEL would make a much better second bet but i here's how i see it:

GE has the most expensive fixtures becuase they gives outrageous deals to bigger utilitis like Forida Power and National Grid.
Cooper has the second highest priced cobrhaead becuase they too give large discounts to companies (which is probably why NGrid turns to them in a "GE crisis".)
AEL has the lowest cost cobrahead because they (as far as i know) don't offer discounts to larger utility companies. That's probably why smaller people like contracters and such use AEL a lot which would explain why GE is used sometimes under MTO (large group) while AEL is generally used on streets by contractors (small group).

Just a guess i suppose but it seems to be the way most things these days work from big company to big company. The little guy gets screwed with a higher price. That's why i really like AEL. Good customer service, not all those corrupt deals with big utilities, and not high prices either.

There used to be 400 watt mercury vapor street lights on the Pennsylvania Turnpike until the 1980's when they were all replaced with 200 watt high pressure sodium streetlights and high mast lighting.

I see both concrete bottom and steel truss bridges...I like them both. Steel trusses look awesome with those huge "I" beams and I like the concrere too..I've always liked concrete and steel and preferred it over wood...

Nice pic !