Tobin Bridge "target" signs

[Alps]

I have a couple of examples of these "targets" on my website - www.alpsroads.net/roads/ma/us_1/0.html, 5th and 6th photos down. The question has been posed to me, what do these targets signify? My first guess is that these are related to which piers support the bridge and which are just columns tying the upper and lower levels together. If anyone has a better idea, I'd love to know.

[shadyjay]

Perhaps they mark locations of hydrant hookups for fire trucks?  Some bridges in Connecticut have them, especially on I-95 at an overpass, so that a fire truck can park on the overpass, hook up, and a pipe takes it down to another hookup on the interstate (or something like that, never seen it in action). 

[Sykotyk]

It's got to be fire hydrants. Only other thing it could be is maybe that's the access point to a catwalk/access under the bridge deck accessed from over the railing.

[roadman]

"Perhaps they mark locations of hydrant hookups for fire trucks?  Some bridges in Connecticut have them, especially on I-95 at an overpass, so that a fire truck can park on the overpass, hook up, and a pipe takes it down to another hookup on the interstate (or something like that, never seen it in action). "

That is correct.  The markers, which were originally installed in the late 1960s, indicate standpipe locations.  It's a dry standpipe system (i.e. no water is normally contained in the pipes), so a fire truck connects to a master connection located at ground level (IIRC there are two ground connections to the Tobin system, one in Chelsea and one in Charlestown), and pumps water up to the bridge level.

The connection ramps to and from the Leverett Connector, as well as the upper/lower decks of I-93, have a similar standpipe system.  Except for portions of the original (1968) I-93 elevated roadway (which have target markers as well), the outlets at roadway level are marked with smaller signs instead of "target" markers.

[SteveG1988]

Or perhaps they are part of a Sponsorship deal.

Target: Just 5 miles from the bridge.


Just a joke.......except that NY has pepsi signs at their toll booths on the bear mountain bridge