Sensors Mag

Big Dig, Big Bummer

May 10, 2006 By: Stephanie vL Henkel, Sensors

E-mail Stephanie vL Henkel

I hope you've heard of The Big Dig in Boston, Massachusetts, because I don't have anywhere near enough space to fill you in on the particulars here. Dan McNichol, who wrote a book about it, called it "the largest urban construction project in the history of the modern world." He's not blowing smoke. But something really nasty's blowing now.

A Few Hints of How Hard It Was

What the Big Dig basically entailed was cutting through the city and making an underground highway out of 42 miles of a central traffic artery built in the 1950s. There was a tunnel, too, and a bridge (the widest cable-stayed in the world) to be constructed. Gas and sewer lines, electrical cables to be relocated. Work to be periodically stopped so artifacts and bits of structures from early times could be salvaged. Boston's been around for a long time. Oh yes, and the city's water table is 15 feet below the surface. The environmental impact studies began in 1983. This underground highway, with its Ted Williams Tunnel, opened last year. The result is a marvel of engineering. Were there cost overruns? What world do youlive in? They might get a little higher, because I suspect that dig's going to need a bunch of sensors—right away.

Drip, Drip. Drip

Apparently some contractors' pockets weren't sufficiently lined. The story's now begun to come out that early leaks in the tunnel and roadway roof were only an advance notice of Big Trouble on the way. First dripping water. Next little chunks of concrete. Then larger ones. Right now, the word on the streets and in the press is that some 5000 loads of concrete brought to the site were old product diluted with water to freshen it up and pass it off as newly made. And in it went. Six arrests so far, and indignation to spare.

Not Rocket Science

I have worked with concrete and with mortar and can tell you it's not that mysterious. Concrete is very forgiving. It can take various formulations depending on where and how it's going to be used. What these mixtures have in common is this: They all have to be poured or otherwise put into place within 90 minutes of mixing or the stuff won't cure properly. Heck, the early Romans built concrete municipal structures and aqueducts that are still standing, and they weren't the first to exploit its admirable properties.

Why I'm Angry

If a concrete contractor or vendor delivered substandard product to be laid as sidewalks here in Peterborough, New Hampshire, I'd be pretty annoyed. But to undermine the brilliant planning and design work of so many environmental, civil, structural, materials, and other engineers just burns me up. What a particularly egregious example of sleaze. But when bucks and brilliance square off, which side usually wins?

The Sensors

The only sensors I'm aware of in that now-underground artery are 30-foot height detectors. There could very well be more. I suggest that if these aren't, they should be added: shock and vibration (with all that traffic trying to tear through before a square yard of roof falls in); seismic (the 1811-1812 New Madrid, Missouri, earthquake rang Boston's church bells); acoustic (to monitor for more pieces as they crack and dislodge); subsidence (obviously); moisture and humidity (again, no explanation needed); and, of course, gas sensors. The time to install these devices was during construction, but retrofits can be done too. Have I left any out? Feel free to nominate them.

Now for an Update and Some News

The New Hampshire Senate wussed out of passing that House bill barring the state from participating in the Real ID Act, the one that will require RFID chips to be embedded in driver's licenses. Instead, that legislative body sent the bill to a study commission, where it could either be talked to death or wither of old age. Meanwhile, there's been a new howl over constant busy signals at the Department of Motor Vehicles. Hard to understand, with two people answering some 22,000 phone calls a week. The situation should get a lot more interesting if the Real ID plan goes through, and DMV employees have to work the phones verifying all those birth certificates, flatlander (i.e., out-of-state) licenses, and other documents that will have to be presented for permission to conduct a vehicle up here.

Yet it's still "Live Free or Die" in the Granite State, visible to the outside world once every four years (think presidential primaries). The Senate, to its credit, voted unanimously to keep pharmaceutical companies from getting hold of our prescription information. This is a national first.

The drugmakers are peeved. The rest of us are feeling a little freer.

Add Comment


Re: Big Dig, Big Bummer
by: sensor1
February 18, 2015 - 2:05am


Thanks for your comment.





Twitter Feed

Find It Fix It Forum

Sensors invites you to join the Findit-Fixit Forum, where you can get answers to your sensing questions—concerning technologies, products, methods, applications, and services--and also offer help to your fellow engineers. The Forum covers all kinds of topics, from the basics to the extraordinary.

Join the discussion!

© Copyright 2016 Questex, LLC. All Rights Reserved. Sensorsmag. Privacy Policy | Terms of Use

If you are having technical difficulties or considerations, please contact the webmaster.