# Well, the "Big Dig" was good value for money. **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [July 11, 2006, 4:56pm UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053 "2006-07-11T16:56:20Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Mithril](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mithril/32/3517_2.png) [@Mithril](https://boards.straightdope.com/u/Mithril)\ **Post date:** [July 12, 2006, 1:15pm UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/21 "2006-07-12T13:15:01Z")
[QUOTE=duffer] As a layman looking at even just the coastline in the bay, instinct tells me the earthen foundation is unlikely to support the weight of what the tunnel can support. Even with reinforcement. Even with modern engineering. Unless I’m way off base, it doesn’t seem the foundation of the area could be reasonably expected to safely sustain the Dig. [/QUOTE] As an intern, I worked for a company that did geotechnical analysis for one section of the Big Dig. I wasn’t privy to it, but the two hours I ever billed to the project were for picking up x-rays of soil cores at MIT. Since then, I have never heard of x-rays being done on cores for any other project, so they took information gathering seriously. There’s just no way that the plans would have been stamped by a Professional Engineer if the foundation couldn’t be expected to sustain the Big Dig. The liability costs are enormous, and I knew at least one of the engineers that would have stamped them. This was not a guy to do it lightly. I’ll poke around and see if I can find information about the foundations and clarify things a little. ---
**Author:** ![Mithril](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mithril/32/3517_2.png) [@Mithril](https://boards.straightdope.com/u/Mithril)\ **Post date:** [July 12, 2006, 1:25pm UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/22 "2006-07-12T13:25:39Z")
Here are a couple of interesting articles. The second one has a photo of what appears to be the installation of a segment like the one that fell. [One](http://www.agiweb.org/geotimes/oct02/feature_bigdig.html) [Two](http://www.tfhrc.gov/pubrds/julaug01/bigdig.htm) ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [July 12, 2006, 1:35pm UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/23 "2006-07-12T13:35:43Z")
For some parts of the dig, at least, the problem isn’t keeping it from sinking, it’s keeping it from floating. The tunnels are hollow and watertight (in theory); put them in soil below the water table and they’ll act like the hull of a ship. In some places, like the approach to the Ted Williams tunnel, the concrete under the road is ten feet thick so there will be enough weight to offset the buoyancy. And from what I understand, Romney has been trying to fire the head of the Turnpike Authority for a long time. Maybe he (the Governor) knew the guy was incompetent and this incident brought it to light, but the story could also play that he’s taking advantage of the tragedy to oust a political rival. ---
**Author:** ![Ponder\_Stibbons](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ponder_stibbons/32/343_2.png) [@Ponder\_Stibbons](https://boards.straightdope.com/u/Ponder_Stibbons)\ **Post date:** [July 12, 2006, 3:14pm UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/24 "2006-07-12T15:14:30Z")
[QUOTE=CynicalGabe] You forgot “Modern Marvels”. [/QUOTE] Not to mention National Geographic’s “Seconds From Disaster”. ---
**Author:** ![ralph124c](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ralph124c](https://boards.straightdope.com/u/ralph124c)\ **Post date:** [July 12, 2006, 3:19pm UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/25 "2006-07-12T15:19:49Z")
The word is that the concrete ceiling panels (3 tons each) were held up by threaed bolts epoxied into the poured concrete tunnel roof. Supposedly, the bolts were tooo short to support the loads. Will lawyers be able to “prove” negigence? not liely-the Governer can’t even get access to the MTA’s files ---
**Author:** ![tremorviolet](https://avatars.discourse-cdn.com/v4/letter/t/e47774/32.png) [@tremorviolet](https://boards.straightdope.com/u/tremorviolet)\ **Post date:** [July 12, 2006, 3:48pm UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/26 "2006-07-12T15:48:19Z")
[QUOTE=ralph124c] The word is that the concrete ceiling panels (3 tons each) were held up by threaed bolts epoxied into the poured concrete tunnel roof. Supposedly, the bolts were tooo short to support the loads. Will lawyers be able to “prove” negigence? not liely-the Governer can’t even get access to the MTA’s files [/QUOTE] I’ll be interested to see if the conclusion is faulty installation (there have already been problems with substandard concrete being supplied) or faulty design. Engineering design always has multiple factors of safety and redundancy built in and most structural engineers take their responsibility for public safety very, very seriously. I’m much more inclined to believe a contractor cut corners somewhere and somehow the inspectors didn’t catch it. ---
**Author:** ![wolf\_meister](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolf_meister/32/15202_2.png) [@wolf\_meister](https://boards.straightdope.com/u/wolf_meister)\ **Post date:** [July 12, 2006, 8:55pm UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/27 "2006-07-12T20:55:24Z")
Here’s a **diagram** of the method used to secure the panel: [http://i5.photobucket.com/albums/y151/wolf\_meister/tunnel.gif](http://i5.photobucket.com/albums/y151/wolf_meister/tunnel.gif) If that has already shown up in one of the links then I apologize for the repetition. **tremorviolet** I too would take the side of the engineers on this one. There has already been talk of sub-standard materials having been used elsewhere in the “Big Dig”. From **mhendo** ’s link: > [@](#): > > In May, six men who supplied concrete to the “Big Dig” were arrested and accused of delivering sub-standard materials to the project. Incidentally, I’m wondering about the credentials of **Matthew Amorello** - the “Turnpike Authority guy” as he’s been called here. During Governor Ed King’s administration (late 1970’s), Mass Port Authority appointments requiring Masters Engineering Degrees were being filled with people who had no more than a high school education. Since that resulted in no one’s death, I guess the Massachusetts citizens (including me) accepted this as the typical corruption, patronage, etc that is so rampant here in the Bay State. Perhaps Tuesday’s fatality will cause some serious scrutiny of our elected officials and state employees. ---
**Author:** ![Sal\_Ammoniac](https://avatars.discourse-cdn.com/v4/letter/s/8dc957/32.png) [@Sal\_Ammoniac](https://boards.straightdope.com/u/Sal_Ammoniac)\ **Post date:** [July 12, 2006, 9:32pm UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/28 "2006-07-12T21:32:35Z")
[QUOTE=tremorviolet] I’ll be interested to see if the conclusion is faulty installation (there have already been problems with substandard concrete being supplied) or faulty design. Engineering design always has multiple factors of safety and redundancy built in and most structural engineers take their responsibility for public safety very, very seriously. I’m much more inclined to believe a contractor cut corners somewhere and somehow the inspectors didn’t catch it. [/QUOTE] I don’t know. Without being an engineer, this ceiling system doesn’t, on the face of it, seem like a terrific idea. You’re relying entirely on the bond between the epoxy and the concrete keeping its integrity over time. There’s no mechanical strength to the joint at all. Plus, why are the ceiling panels concrete? Each one apparently weighs several tons. Why not a lighter material? ---
**Author:** ![Sal\_Ammoniac](https://avatars.discourse-cdn.com/v4/letter/s/8dc957/32.png) [@Sal\_Ammoniac](https://boards.straightdope.com/u/Sal_Ammoniac)\ **Post date:** [July 12, 2006, 10:04pm UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/29 "2006-07-12T22:04:57Z")
Oh, and as to the whole Big Dig, I also thought it was a huge boondoggle. That said, it has improved traffic flows in the city in certain important ways. There’s now a connection between Interstates 90 and 93, access to the airport has improved, and some of the connections around Leverett Circle are not as nightmarish as they once were. And certainly tearing down the elevated highway means you can reknit halves of the city that were torn apart by the Central Artery. (The unfortunate corollary is that where you used to get a beautiful view of the city as you passed through on the elevated highway, now you get a view of dreary tunnel walls.) So yeah, in a general sense, I would say the Big Dig has improved Boston. But was it worth it at the price? That’s the $20 billion question. ---
**Author:** ![EddyTeddyFreddy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eddyteddyfreddy/32/18796_2.png) [@EddyTeddyFreddy](https://boards.straightdope.com/u/EddyTeddyFreddy)\ **Post date:** [July 12, 2006, 10:13pm UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/30 "2006-07-12T22:13:26Z")
One of the news broadcasts I watched last night said that the panels were so thick because they were part of the air plenum system for the tunnel and had to be strong enough to handle the force of the air flow. At least that’s how I recall that part of the report. Checking the _Boston Globe’s_ [website](http://www.boston.com), I find [stuff like this:](http://www.boston.com/news/globe/city_region/breaking_news/2006/07/reilly_anchor_b.html) > [@](#): > > Attorney General Thomas F. Reilly said at an afternoon press conference that anchor bolts similar to those involved in the partial collapse of the Interstate 90 connector tunnel failed field studies as far back as 1999. > > [snip] > > “The problem with the anchor bolts was identified in the fall of 1999,” said Reilly, whose office has launched a negligent manslaughter investigation. “It was not only identified, but there was a plan to address that problem.” > > Five of the anchor bolts gave way in the 1999 study, Reilly said, referencing documents unearthed during the probe by his office. Investigators are trying to determine what was done with the plan formulated to fix the problem. > > [snip] > > Investigators have determined that the contractor and Bechtel/Parsons Brinckerhoff, the main company behind the Big Dig, knew about the issue, Reilly said. > > “I have no information at this point that this information was brought to the attention of the Turnpike Authority,” Reilly said. > > The bolts that failed Monday had been anchored in the concrete ceiling with epoxy, but not affixed to a metal support rail, as was done with ceiling panels in other tunnels in Boston. The tiles facilitate airflow. ---
**Author:** ![EddyTeddyFreddy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eddyteddyfreddy/32/18796_2.png) [@EddyTeddyFreddy](https://boards.straightdope.com/u/EddyTeddyFreddy)\ **Post date:** [July 12, 2006, 10:19pm UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/31 "2006-07-12T22:19:30Z")
More from the _Boston Globe_ website as the [ramifications explode](http://www.boston.com/news/globe/city_region/breaking_news/2006/07/tunnel_closed_i.html). Happy commuting, and abandon hope, all ye who enter Boston: > [@](#): > > Massachusetts Turnpike Authority chairman Matthew J. Amorello stood with engineers at a press conference today and said that the Interstate 90 connector tunnel that partially collapsed Monday would remain closed indefinitely while investigators try to determine what went wrong. > > “I can’t give you a timeline,” said Amorello, adding that crews are in the process of removing all of the three-ton ceiling panels from the 200-foot tunnel where 38-year-old Milena Del Valle died. > > [snip] > > Transportation crews plan to inspect all highway infrastructure in metropolitan Boston inside Route 128, Amorello said. That includes the Sumner, Callahan, and Ted Williams tunnels, the Zakim Bridge, and the tunnels on the Massachusetts Turnpike and the Southeast Expressway. > > **Inspectors have already found 60 more problem areas in the eastbound lanes of the connector,** which links the Massachusetts Turnpike with the Ted Williams Tunnel. Crews are still checking the westbound lanes. > > [snip] > > The other tunnels in the Turnpike Authority system used a different method of securing the ceiling tiles, anchoring the slabs to a metal rail. ---
**Author:** ![tremorviolet](https://avatars.discourse-cdn.com/v4/letter/t/e47774/32.png) [@tremorviolet](https://boards.straightdope.com/u/tremorviolet)\ **Post date:** [July 12, 2006, 10:39pm UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/32 "2006-07-12T22:39:01Z")
[QUOTE=Sal Ammoniac] I don’t know. Without being an engineer, this ceiling system doesn’t, on the face of it, seem like a terrific idea. You’re relying entirely on the bond between the epoxy and the concrete keeping its integrity over time. There’s no mechanical strength to the joint at all. Plus, why are the ceiling panels concrete? Each one apparently weighs several tons. Why not a lighter material? [/QUOTE] The epoxy/bolt systems are not unusual in engineering design and have a good, extensive track record (provided they’re installed properly). When you need to bolt something to a concrete or rock face, you don’t have many other economical options. This [page](http://www.williamsform.com/Concrete_Anchors/Epoxy_Concrete_Anchors/epoxy_concrete_anchors.html) has some information about anchoring systems. Look at the lowest rated bar in the charts at the bottom of the page (top row, third chart). It has a stated working load (with a factor of safety of four which means they established what it actually could hold and then divided by four) of 4.5 kips. A kip is 1000 pounds or half a ton. The panels weighed only 3 tons or 6 kips which sounds heavy but are actually pretty light. They must be only around half an inch thick. Anyway, you can see from the illustration **wolf\_meister** linked, each panel has multiple anchors holding it up. The number of anchors was probably driven more by the geometry of the panel supports thanthe minimum number of anchors needed. Things like anchors are pretty cheap and most engineers would throw extra in “just to be safe”. In the illustration, I see six anchors for one end and I would think the other end would have the same configuration (I would actually bet there’s more in the middle of the panel since the panel is so thin). So assume twelve anchors holding up a half of two different panels. 12 anchors x 4.5k = 54 kips or 27 tons \>\> 3 tons So, on the surface, it’s really overly designed. I really think it’s going to be a case of improper installation or bad materials. ---
**Author:** ![wolf\_meister](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolf_meister/32/15202_2.png) [@wolf\_meister](https://boards.straightdope.com/u/wolf_meister)\ **Post date:** [July 13, 2006, 4:32am UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/33 "2006-07-13T04:32:51Z")
Here’s a better graphic: [concrete panel](http://www.geocities.com/internet_web_surfer_dude/tunnel.gif) (Actually it’s the same exact graphic but the detail is _much_ better. The first one I uploaded to Photobucket which limits a file’s size. The new link goes to a free geocities website.) ---
**Author:** ![KGS](https://avatars.discourse-cdn.com/v4/letter/k/90ced4/32.png) [@KGS](https://boards.straightdope.com/u/KGS)\ **Post date:** [July 13, 2006, 4:42am UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/34 "2006-07-13T04:42:02Z")
> [@Boston Globe](#): > > Massachusetts Turnpike Authority chairman Matthew J. Amorello stood with engineers at a press conference today and said that the Interstate 90 connector tunnel that partially collapsed Monday would remain closed indefinitely while investigators try to determine what went wrong. Oh dear. Do you Bostonites still have that above-ground freeway to fall back on, or are you all fucked?? ---
**Author:** ![wolf\_meister](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolf_meister/32/15202_2.png) [@wolf\_meister](https://boards.straightdope.com/u/wolf_meister)\ **Post date:** [July 13, 2006, 5:59am UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/35 "2006-07-13T05:59:34Z")
As for me, I take public transportation which is … well it’s better than walking. I don’t have a car because (as you may know), the insurance rates in this state are ridiculous. Yeah, this might be an indication for me to leave the state. ---
**Author:** ![Hippy\_Hollow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hippy_hollow/32/4841_2.png) [@Hippy\_Hollow](https://boards.straightdope.com/u/Hippy_Hollow)\ **Post date:** [July 13, 2006, 6:10am UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/36 "2006-07-13T06:10:42Z")
[QUOTE=KGS] Oh dear. Do you Bostonites still have that above-ground freeway to fall back on, or are you all fucked?? [/QUOTE] One can go through Chelsea to get to Logan (cue Elvis Costello’s _"(I Don’t Want To Go To) Chelsea_) but it takes forever. Otherwise you can go via the Callahan/Sumner tunnels. You can drive on the surface roads in Government Center, but most likely you would come through the tunnel from I-93 North or South, or Storrow Drive. The concrete ceilings in the I-93 tunnel are apparently different from the ones that were in the I-90 tunnel, but there’s been falling debris and flooding in the I-93 tunnel as well. They dismantled the “other Green Monster” - the elevated Fitzgerald Expressway - starting before the Democratic Convention in 2004 (which looked totally weird) and it’s now completely gone. But I’m glad. If you were sitting in traffic on the Fitzgerald you could feel the roadway shake - quite a bit - more than I’m comfortable experiencing. Good riddance to bad rubbish, I say. But I don’t recall it ever falling and killing anyone. ---
**Author:** ![Sal\_Ammoniac](https://avatars.discourse-cdn.com/v4/letter/s/8dc957/32.png) [@Sal\_Ammoniac](https://boards.straightdope.com/u/Sal_Ammoniac)\ **Post date:** [July 13, 2006, 12:25pm UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/37 "2006-07-13T12:25:15Z")
[QUOTE=tremorviolet] The epoxy/bolt systems are not unusual in engineering design and have a good, extensive track record (provided they’re installed properly). When you need to bolt something to a concrete or rock face, you don’t have many other economical options. … So, on the surface, it’s really overly designed. I really think it’s going to be a case of improper installation or bad materials. [/QUOTE] Maybe so, but shouldn’t the engineer at least allow for the possibility that the installation will be substandard? This type of installation is hardly foolproof. Moreover, there’s no guarantee that the particular square inch of concrete into which you’re boring the hole for the bolt has all the integrity of the concrete sample in the lab. In fact, there’s a record of failure with this type of installation going back to the late '90s, as today’s paper reveals. This ceiling was like a sword of Damocles, and even if the installers were to blame, I don’t think the engineering is all that defensible. Off the top of my head, I could come up with a half dozen safer solutions. Sure, they’re probably more expensive, but in the context of the whole job, the cost would probably be negligible. ---
**Author:** ![Mithril](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mithril/32/3517_2.png) [@Mithril](https://boards.straightdope.com/u/Mithril)\ **Post date:** [July 13, 2006, 12:39pm UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/38 "2006-07-13T12:39:31Z")
[QUOTE=Sal Ammoniac] Maybe so, but shouldn’t the engineer at least allow for the possibility that the installation will be substandard? [/QUOTE] **tremorviolet** ’s back-of-the-envelope calculations give a factor of safety of 36 (nine was applied to the system by the engineer, four by the manufacturer). That’s a pretty good accounting for the chance of substandard installation, don’t you think? By way of comparison, factors of safety for, let’s say, a dam, will typically range between 1.4 and 3.5 depending on the analysis. My brother, a mechanical engineer, tells me that the overall factor of safety for an airplane is about 1.01 (but that’s word of mouth, so don’t quote me on that, please) That said, a photo of the anchors was sent around my office, and the general ‘gut feeling’ was that any of us would have put in bigger anchors. If we had looked at the specs for the anchors, though, that might have changed. ---
**Author:** ![BobLibDem](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/boblibdem/32/3149_2.png) [@BobLibDem](https://boards.straightdope.com/u/BobLibDem)\ **Post date:** [July 13, 2006, 1:03pm UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/39 "2006-07-13T13:03:45Z")
Epoxy anchors are pretty standard stuff in bridge rehabilitation. When installed correctly, they’re quite reliable. I’ve never heard of one failing in my state. Exactly what is the function of the ceiling? Is it just aesthetics or something to do with air flow? ---
**Author:** ![EddyTeddyFreddy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eddyteddyfreddy/32/18796_2.png) [@EddyTeddyFreddy](https://boards.straightdope.com/u/EddyTeddyFreddy)\ **Post date:** [July 13, 2006, 2:56pm UTC](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053/40 "2006-07-13T14:56:23Z")
[QUOTE=BobLibDem] Epoxy anchors are pretty standard stuff in bridge rehabilitation. When installed correctly, they’re quite reliable. I’ve never heard of one failing in my state. Exactly what is the function of the ceiling? Is it just aesthetics or something to do with air flow? [/QUOTE] [From today’s Boston.com - Boston Globe - headline story:](http://www.boston.com/news/traffic/bigdig/articles/2006/07/13/need_for_heavy_panels_was_debated/) > [@](#): > > The engineer who oversaw completion of the Interstate 90 connector said in an interview with the Globe yesterday that he questioned the need for heavy concrete panels in the tunnel’s drop ceiling when he came on the job, but that he didn’t press the issue with senior Big Dig officials, because the ceiling work was already well underway and he was persuaded it was being done safely. > > [snip] > > Officials of the Massachusetts Turnpike Authority said yesterday that the concrete panels were part of the tunnel’s ventilation system and needed to be heavy to remain still when powerful fans operated at full power. > > But some have questioned whether the slabs were needed at all, since their main purpose was to improve air circulation and fresh air was already entering at the entrance to the tunnel 200 feet away. > > James Bruno, who served as project manager for Modern Continental on the $91 million contract to complete the connector tunnel, said that he and other construction managers suggested in meetings with Big Dig officials using lighter material for the ceiling, pointing out that the side walls of the tunnel are made of thin metal. > > ``You’re just controlling air here; you don’t need heavy concrete slabs," said Bruno, now a senior project manager at Beacon Consulting Group. > > But he said senior Big Dig officials were not interested in using a lighter material, because doing so would have required many more supports to prevent the ceiling from vibrating. A lighter material is generally less sturdy and more likely to shift in the face of wind or vibration from traffic. > > [snip snip snip] > > The drop ceiling in the nearby Ted Williams Tunnel is affixed to the actual ceiling in a similar fashion, but Turnpike Authority officials said yesterday that panels in the connector tunnel ceiling were at least six times heavier than ones used in the Ted Williams Tunnel, which were a thin composite of metal and concrete that weighed about 800 pounds each. > > But Michael P. Lewis, the state’s Big Dig project manager, said during a press conference yesterday that the panels in the I-90 connector needed to be heavy for stability in the face of ``hurricane force winds" generated by fans near the roof of the tunnel. In an emergency, such as a tunnel fire, Lewis said, the fans would be turned up to maximum velocity to bring in fresh air, requiring a heavy drop ceiling that would not vibrate. [Previous page](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053.md?page=1) [Next page](https://boards.straightdope.com/t/well-the-big-dig-was-good-value-for-money/364053.md?page=3)