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February 29, 2008

Tracking Construction Progress by Satellite

I drove down to Los Angeles last weekend and crossed the Benicia-Martinez Bridge. It carries Interstate 680 across the Carquinez Strait, northeast of San Francisco, and is the bridge you would cross if driving from (say) Sacramento to San Jose. I know, you are all thinking, "If you insisted on detouring towards the Bay Area, how come you didn't head just a bit further west to cross the Al Zampa Bridge?", all I can say is that I was in a bit of a hurry (a poor excuse, agreed).

The Benicia-Martinez Bridge is now two bridges, with southbound traffic on the old bridge and northbound traffic on the new bridge, which opened last August after being under construction for several years (there is also a railroad bridge which sits between the two road bridges). I was looking at satellite photos of the bridge, and noticed that different sites captured different phases of construction of the new bridge.

First you have the Google Maps view, where about half the piers haven't been started. On Yahoo Maps the piers are mostly above the waterline. In the Live Maps image the piers are done and parts of the roadway are in place. Mapquest has the roadway almost complete. And on TerraServer the bridge looks finished (if you want to look at different systems, start with the WikiMedia GeoHack page for that location).

I was actually expecting that they would all be sharing the same satellite imagery, or maybe a couple of different sets; the fact that all 5 were different is surprising. And if you knew the details of when the bridge was constructed, you could actually tell pretty closely when each picture was taken.

Posted by AdamBa at February 29, 2008 10:13 PM

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Comments

Posted by: RockHard at April 3, 2008 04:45 AM

Posted by: oztvpr at April 3, 2008 01:11 PM