The Big Dig Ceiling Collapse: An Epoxy that took down a Tunnel Ceiling

On the 10 of July 2006 the ceiling of the big dig tunnel collapses. This was 9 years after the fort point channel opened to traffic. So what was the cause of this collapse of the ceiling of the tunnel on the I90 in Boston?

I will cover the history around the constitution of the big dig tunnel and what the NTSB uncovered in their investigation into this tragedy. You will find out the causes behind why the ceiling of the fort point tunnel collapsed, what decision led up to the tragedy, and was there warning signs prior to the collapse of the ceiling on the big dig tunnel.

It is important that all engineering understand both the structural mechanics behind the failure, but also understand the decision the led up to the tragedy and how human physiology can play a role in an engineering disaster.

The true cause of the big dig ceiling collapse in epoxy with the same name that had two versions, a fast set and a standard set. These epoxies produced by Power Fasteners had performed similar in a short term loading situation but had drastically different properties under a sustained load. One of these epoxies suffers from an issue known as Epoxy Creep, which means over time under a sustained load the epoxy will stretch and weaken to an eventual point of failure.

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My name is Brendan and I am a structural engineer with over 15 years of experience based in Australia. I have a wide variety of projects from very small to some of the biggest in the southern hemisphere. I have a passion for good structural design and teaching/mentoring.

This channel is to share my passion for engineering and provide entertaining short clips on:
- tips for young engineers on progressing their careers
- anyone needing a refresher on any design element
- design approaches
- Review past engineering failures to improve structural knowledge
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Disclaimer: Some of the below links are affiliate links as an Amazon Associate and other affiliate programs I'll earn a small commission from qualifying purchases at no additional cost to you.
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Chapter
00:00 Intro
00:50 Main Structural Elements in a Tunnel
01:43 Type of Post fixed anchors
03:24 Structural issues during construction
05:39 The Investigation
07:05 The Remaining Ceiling
07:27 Was installation at fault
08:27 What is Epoxy Creep
10:17 What did Power Fasteners Know
11:10 NTSB's Conclusions
11:27 Additional findings

[DeepakKrishna]

Amazing Brenden, this case alone shows us the importance and impact of decision making.

[zachnuketown]

I was 6 when this happened and my father always brought us to New Hampshire to go camping every summer. I clearly remember not long after this accident, entering the tunnel on our way up to Nh and all of us being pretty uneasy. And the big cheers when we finally got through to the other side.

[martinmukisakuzegera]

Thanks Brendan for your content...always exciting...am not following any series now other than this page

[christhorney]

im not sure how hammering a dynabolt into a hole is harder than putting 2 part epoxy, then screwing a rod in, then waiting for it to set before applying load and the rest of the drawbacks from epoxy, how is it cheaper and easier to install? either way your drilling a hole thats the hard bit done, hammer a dynabolt in VS mixing, then applying epoxy, dealing with the mess it makes, and the environmental impact.. i could go on, it blows my mind lol. Also when you said "the national beuro of transport safety, or the NTSB" i cracked up. thanks for another great informative film

[henrimauritz]

I like you videos about structural failures. What I find helpfull is to analyse the safety of a design by means of the four safety principals: robustness, redundancy, progressive collapse and plasticity. They can be applied to a new design or to analyse the issues with failed designs (collapses). Robustness: the ability of a structure to resists a totally unexpected situation. Redundancy: the ability of a structure to carry loads by an alternative load path. Progressive collapse: occurs when a structure is damaged to a large extent as a result of an initial (small) local failure. Plasticity: the ability of a structure to anticipate to a sitution, for instance by adapting another structural scheme. At uni, we got the assignment to choose a collapse and apply these principals to find out what went good/wrong. Very interesting.

[sambopu]

Thanks for the video, informative and easily digestible.

[MsDJ]

Amazing video Brendan, keep up the good work!

[Karimclean]

This was a good video, can you make more videos similar to this? Structural disasters. I’d love that series!

[yadoud]

You deserve so much more subs and views!!!! Keep up the good work!

[mukasaelton]

These are deep knowledge issues that require critical thinking of someone very well informed to find value in them. You have given engineers and the world at large more than you know. In my experience (am from a 3rd world country so this might be different for most people) structural failures are normally a result of economical aspects of the project. Usually the contractor wants to save more money by going the cheaper way or the client wants to pay for the cheaper options in disregard of the structural engineering implications. From this i suspect a collusion between the epoxy company and the contractor though the epoxy supplier has more to explain.

[dracula-dead]

Truly enjoy your knowledge. Thanks and pass this on to like minded people. Peace.

[digger]

Unfortunately, you don't have all the information. I worked with the guy who was the crew boss who installed the bolts. The contractor found it was too expensive to use the correct drill bits, which left a swirl groove in the hole. They also used a third epoxy product that was not mentioned, a version of the epoxy that was way cheaper, but was designed for down anchors, not overhead. The true cause was covered up and Powers fastener took the blame. All their products were than banned for use in all Ma highway projects for a couple of years. The true culprit went un punished because of political connections. The guy( the installer) testified in court these facts and his reports about concerns of using the wrong drills and the wrong epoxy product were sealed and buried in the records. NTSB is a political creature like most government agencies.

[dramatyst]

I remember when this happened, I had just got my license and drove through that tunnel frequently

[FreeOnGoal]

What type of anchor did they use in the repair?

[AllFallBeforeMe]

Piss poor design. Bolts could be thicker with wider and deeper threads and/or could be installed at 45 degree angles so the bolts can't just slide straight down.

[srpeabs]

The tragedy you refer to is a person! Maria Devale of Jamaca Plain died as she and her husband were headed to Logan. MARIA should be remembered. I'd like to see a plaque. I think of and often speak her name when I pass that spot. I'm an Uber driver so that happens several times per day.

[repairdrive]

If those panels weren't doing anything other than creating a false ceiling why make them out of heavy concrete ?!?!

[billfarmer]

if they cast the anchors into the top of the tunnel they wouldn't have been a way for them to fail

[martinvannostrand]

Your audio sounds incredibly distorted

[colclumper]

Good old creep, the reason not to accelerate the set times