recap

[kirkcudbright]

So here I am in California again. Recall that I have some issues with the place.

I'm in Redwood City for the annual all-hands meeting. The last time I did this, my horse was put down while I was en route. New year, new horse...

Wednesday, I took my horse to the beach, and she was fabulous. I was a spaz, and left my helmet at the barn, so I resolved not to fall on my head. There also aren't any overhanging branches at the beach, which is what the helmet usually saves me from. In any case, Gemini was wonderful, ears up, looking around, lots of energy, but always under control. The hand gallop never turned into an out-of-hand gallop. The only trouble was getting her back on the trailer to go home, I think because it's black inside, and it was just about sunset. Oh yeah, and there was some head-tossing when she got excited (spit flying in my face), but if that's her worst fault, I can live with it.

Thursday, Kylie and I took advantage of the freakishly warm weather to visit the Newburyport parks. We'd been heading for Maudley State Park, but wound up at the trailhead for Mosley Woods instead. I didn't mind, because it gave me an opportunity to get pictures of the Chain Bridge, the only suspension bridge in Massachusetts. (I see it every time I cross the I-95 bridge, but that's not really a good place to stop and take a picture.) Unfortunately, those pics are at home, so you're going to have to wait for them.

Friday, I had my first shift as an MSPCA Volunteer Mentor. I practised on lyonesse and pywaket a couple weeks ago, but this time it was total strangers. I think it went well, and they seemed well served by it.

Saturday, it snowed and all that, and you know the rest.

Comments

[totient]

Technically there are three suspension bridges in MA. The Chain Bridge is the oldest and most legitimate. But the Zakim is of course partly a suspension bridge (not 100%, because the geometry doesn't work, but partly). And there's a suspension footbridge in the Public Gardens, though that one gets almost none of its support from the stays.

Nope, only two.

[c1.livejournal.com]

Quoth the Comm. of MA:

Significance of Bridge

The only known suspension bridge in the MassHighway database, and one of only two known suspension bridges remaining in the state (the other being the 1866 eyebar chain suspension bridge in Boston's Public Garden, which no longer functions structurally as a suspension bridge, as a result of an early 20th century remodeling). Little altered and visually arresting. It is located on the site of two earlier bridges which were of national significance.

Within the development of the suspension bridge structural type, this is an essentially "modern" design in that it uses steel wire cables (rather than link or eyebar chains), has a nearly horizontal deck, center-hinged stiffening trusses, and no stay cables.

The Zakim is actually not at all a suspension bridge, but a cable-stayed bridge.

Essentially, in a suspension bridge, a large "cable" (built of a multitude of thin cable strands) is built up, where each end is anchored into the ground at either end of the bridge. Support for the bridge deck is provided by thin cables anchored to the bridge deck on one end, the large cable at the top end. The strength of the bridge is a product of the anchors at each end of the large cable.
In a cable stayed bridge, thin cables are connected to the bridge deck at one end, and to towers along the bridge at the other. The towers are the source of strength.
Source: Wikipedia (http://en.wikipedia.org/wiki/Cable-stayed_bridge)

In Boston, there's no way the crummy excuse for solid ground that supports Boston could withstand the force generated by a true suspension bridge.

Wikipedia and authority

[totient]

Beware of citing Wikipedia, for it contradicts itself. this wikipedia page currently states that "A suspension bridge is any type of bridge that makes significant use of tension rather than or in addition to compression". And the state page you cite dates to before the completion of the Zakim.

Re: Wikipedia and authority

[c1.livejournal.com]

Sure!
At the time the Zakim was being built, I was working on an art project in the immediate vicinity, and spoke with several of the bridge engineers. (A factoid I learned from those engineers is that the Zakim can lose about 20 of its cables before it's in deep water.)
Whatever the wikipedia page shows, it's still a cable stayed bridge, and it doesn't bury any of its cables in the earth-- something suspension bridges do.

Compare the Tampa Bay Sunshine Skyway (http://bridgepros.com/projects/Sunshineskyway/Sunshineskyway.htm) and the Golden Gate, for example-- two well-known examples of each bridge type.

A PBS NOVA page on cable-stayed bridges:
http://www.pbs.org/wgbh/nova/bridge/meetcable.html