I am a tunnel boring machine operator—the person who operates the actual tunneling machine. I've worked in the tunneling industry for 32 years and built 20+ tunnels around the world. Ask me anything about tunneling and boring machines. Anything about how the machines work, what we do underground, aspects of our job.

(* I am his son Zach. I will be writing my dad's answers for him from my account.)

PROOF: https://imgur.com/a/VGfpK7m

Comments: 230 • Responses: 39  • Date: 

amikingtutorwhat61 karma

That's rad! What's the speed of a tunnel borer and how.much does it weigh?

zachboth89 karma

The machine in Connecticut can tunnel roughly 130 feet in 24 hours on a good day with three shifts working a day. The type of ground affects this speed a lot. It weighs approx 300+ tons.

AndEllie43 karma

What's a typical income for this position?

zachboth74 karma

My wife has always been happy with my paycheck.

AndEllie29 karma

Cool! So to continue asking you anything: About how much is a typical pay scale for this position?

zachboth64 karma

A TBM operator starts at low six figures. But so do many construction jobs that require experience.

SaltySnowman833 karma

Where do you poop when you cant hold it?

zachboth122 karma

We have "shitters" (a technical term) inside the tunnel boring machine. In the old days, we use to put a toilet seat above the conveyer belt that took the rock out of the tunnel haha.

plotplottingplotters33 karma

Have you ever found any interesting fossils underground?

zachboth85 karma

Coolest thing I've found has been whale teeth and a flake of gold. You find cool crystals regularly though.

Slow-Down_Turbo28 karma

Hello! Nocam Menses here, are underwater tunnels more of a marvel than convenience?. Are they safer than above water tunnels?

zachboth53 karma

Depending on the quality of construction, above ground tunnel and underwater tunnels are equally safe. I built a tunnel under Lake Michigan that was 30ft below the lake bottom and went a mile and 3/4 out. It was a 27ft water intake tunnel for the power plant.

dangerous_dude26 karma

Thanks for doing this AMA! I used to work for some of the big underground contractors an engineer. I've helped bid jobs for TBM's but have never gotten to see one in action. What is the worst thing you've had happen on a job as a TBM operator?

zachboth43 karma

The worst thing is always when someone is seriously injured on the job.

dangerous_dude19 karma

Thank you for the response! Outside of injuries, what else has gone terribly wrong? Have you had extended downtime on the TBM due to a major issue? Have the wrong tunnel segments been put in place? Any experience with the tunnel flooding?

Do you have any preference between Herrenknecht or Robbins TBMs?

zachboth24 karma

Yes, yes and yes. Sink holes are a bad day for sure.

They both have their strengths. I still miss Lovat machines though.

ismisedaithi26 karma

Does it ever get a bit boring boring?

Jokes aside, besides location is it the same thing on a daily basis?

zachboth28 karma

There's always some excitement going on with the mining process, so its never boring. The process is pretty similar day to day but you never really know what is in front of you that can throw you some curve balls... especially in soft ground.

bateschas26 karma

I’m a mining engineer and I am curious how many tons per hour of rock did the TBM generate building that tunnel?

zachboth52 karma

With this diameter (21 feet), the machine generated roughly 30 tons and hour of red rock.

soaring-arrow20 karma

Did you abandon the machine in a side tunnel or dismantle and remove it?

What was the depth and length of the tunnel? Were there any trades behind you that were required to support the tunnel or it self supporting?

--- secondary question, what was the worst soil you've had to bore thru?

--- another secondary question, have you ever had to worry about the bends?

How many months on this particular job?

How did you handle groundwater?

I'm assuming you're a union employee?

zachboth50 karma

On this project we will dismantle the machine entirely, but on other projects we strip the machine of its main components and abandon it underground on the side or mine further ahead and poured in with concrete. On some hard rock tunnels, is backed out of the tunnel if there is not a retrieval shaft.

On this tunnel it was 200ft deep and total length was a little over 4 miles. 36 month project. There are various trades such as laborers, operating engineers, electricians that support that ongoing tunneling operation.

The worst soil I've had to bore through was liver sand in Seattle.

No bends (I think you're talking about "bends" like scuba diving), but we have had to do pressurized interventions to change the cutting tools that does have pressure like in the ocean.

You probe ahead of the tunnel and if you hit substantial water, you grout it with liquid cement to try and stop the water.

Yes, I am a union employee since the beginning. 10 years as a laborer and the rest as an operating engineer.

soaring-arrow16 karma

This is so cool! I toured the east side access a few years ago and loved it :) Thanks for the response.

Yes, I meant the bends like suba. I've heard that theres that issue with some bridge footing installs, which is why I asked

What is liver sand?

zachboth33 karma

Liver sand is very fine sand that flows like water. And when it is under pressure it can create a lot of problems on a tunneling project.

TexansforJesus16 karma

Fantastic pic! I recall the mess with Bertha on Alaskan Way. Any fun times like that here?

Also, I presume there is a concrete tunnel liner. How far did you have to pump to get the liner done?

zachboth18 karma

The closest "Bertha" on the East Coast will be Hampton Road, Virginia which will be 46 ft in diameter. I hope it goes better for them than Bertha.

This particular tunnel was lined with a six piece segment ring that was 5 feet long.

dumb_commenter15 karma

Do you ever find it to be spooky down there? Does it take much getting used to for newcomers? Do you get to see much daylight between work and sleep?

zachboth31 karma

When the power goes out and its dark, it always feels like there are ghosts around.

As far as newcomers, some people just can't handle confined spaces no matter how big the tunnel is. There's only one way in and one way out.

On certain shifts and times of year, it can be dark when I go into the tunnel and be dark when I get out.

goobly_goo15 karma

What is the tunnel for?

zachboth33 karma

Its to help with flooding issues in the area during storms. The tunnel will be able to store 42 million gallons of overflow sanitary and storm waste instead of it just being pumped into the Connecticut River.

That_Guy38114 karma

What do you do with all the rock that’s been mined out? Does it have any use?

zachboth28 karma

In Milwaukee, they used the rock to protect their lakefront. In Chicago, they made a ski hill out of the rock. Other projects use it for various fill in construction projects. And no, most companies aren't making bricks ;)

That_Guy3817 karma

Really! What ski hill in Chicago, if you know

zachboth4 karma

I don't remember, sorry.

CH1CK3NW1N9513 karma

When you're operating your machine, what's the absolute worst-case "oh please fuck don't let this happen" scenario?

What's the largest safety fucky wucky that's ever personally happened to you?

zachboth31 karma

Tunnel collapse would be the absolute worse case scenario. Luckily, I've never experienced a tunnel collapse (knock on wood). Almost did though. A gas explosion would be bad too.

Worst case though: the porta potty is full.

rudogandthedweebs12 karma

How did you get into this job? What is the best thing about the job? What is the worst thing? How deep underground have you gone? Where around the county/world has your job taken you?

zachboth36 karma

Started in Milwaukee, Wisconsin on a deep tunnel project as a laborer/miner.

Best thing about the job is I build things that are genuinely useful for society... and the money is not bad ;)

Worst thing is working away from my family.

Deepest tunnel has been 1800ft in a salt mine in Cleveland, Ohio.

My projects have taken me to Germany, Israel, Milwaukee, Chicago, Seattle, Los Angeles, Columbus, Akron, Providence, and Hartford.

SeanInMyTree23 karma

And Albuquerque, but we know you can’t talk about one

zachboth26 karma

There's secret tunnels everywhere ;)

rob_allshouse11 karma

Since you’ve commented about not knowing what you may encounter, how do they know there won’t be permanent damage to sky scrapers above tunnels like this?

zachboth34 karma

Proper engineering and planning avoids problems above.

Doc_Irocz11 karma

Drilling engineer question without a lot of mining experience: how’s the machine work? It looks like rolling cutters but does it have any percussion function? Does the entire face of your bit turn?

zachboth13 karma

No percussion. It just rotates cutting the rock and soft ground as you advance the machine.

PeekaB00_10 karma

How do you deal with the chemicals/lack of oxygen down there?

zachboth14 karma

Any chemicals we use are environmentally friendly and we have constant ventilation that is pumped into the heading of the TBM.

Quincyguy48 karma

What do you think of the Elon musk project ?

zachboth62 karma

Currently, they are not doing anything that has not been done before. The machines he's using are the same machines we all have been using for decades. Maybe that will change in the future, but I hope he also changes his stance on labor unions.

Zkenny137 karma

What would burrowing through clay be like? Would it be possible? Would you guys just look for another spot?

zachboth11 karma

Boring through clay is common on soft ground tunneling projects but there are additives to alleviate the stickiness of the clay.

nahnprophet7 karma

Is anybody gay for Moleman?

zachboth20 karma


*This response is from his son. My dad does not get the reference lol

89Hopper6 karma

I'm a mining engineer and have also worked as a Jumbo Operator but never worked on a civil project or with a TBM. Have you always been on projects that use TBMs or did you start your career using things like Jumbos and road headers and work your way up.

Also, what is the method of installing ground support? I'd guess you use concrete forms but does the TBM have a method of bolting them in or do you use a seperate machine to place and bolt?

zachboth8 karma

I started out as a laborer doing shaft exploration drilling and grouting. I've drilled with jumbos and used road headers but my main expertise are TBMs.

The segment erector is an integral part of the TBM. It lifts and places the concrete segments that are one foot thick into place. Six pieces are erected and bolted together.

doggrimoire6 karma

Do the tunnels echo like crazy or are sounds more muffled?

zachboth9 karma

When they're drilling and shooting with explosives there can be quite a bit of echo. But in the normal TBM tunneling environment its just normal construction noise.

Vernonandon5 karma

Are you and your crew looking for a new project now this one is completed?

zachboth10 karma

I go from tunnel project to project as an individual employee. A lot of the crew is local to the area.

SmackEh5 karma

It snowed here yesterday, and I built a pretty sweet tunnel. I'm told snow tunnels aren't safe. Any advice?

zachboth20 karma

Don't go in your snow tunnel above 32 degrees Fahrenheit. Sounds cool though.

RainbowRoadMushroom5 karma

How do you decide which projects to be involved in? Location? Geology? Managing company/unions? (P.S. I applied to be part of the pre-tunneling characterization work for the SHCST project, which I think is the one you are on, but was not hired).

zachboth12 karma

I ask my wife lol. But seriously, I've been with the same company for the last 20 years. They've always taken care of me and have had interesting projects to be part of.

Arrowtica4 karma

So your job is literally boring?

zachboth4 karma

SO much boring.

Grumar4 karma

What's the most wicked yet horrifying death you've witnessed on the job?

zachboth37 karma

We had an amazing safety record on this Connecticut job and no one has died on this project. Years ago, when tunneling companies were bidding projects they would estimate 1 death per mile of tunnel. That is not acceptable in today's tunneling business.

chgopanth3 karma

Ever get caisson disease?

zachboth5 karma

Nope. The technology for going under pressure has advance to the point that people getting caisson is very rare in today's business.

wolterjwb3 karma

Are all tunnels dug basically the same size? I ask as it doesn’t seem like the tunnel boring machine is something you get in small, medium, large. More of “this is the size you get so plan accordingly”

zachboth11 karma

Tunnel boring machines come in all different sizes depending on the project, from micro tunnels that are 3 feet in diameter to the largest machine that was 50 feet in diameter.

sonofabutch3 karma

Best use of a borer machine in a movie and why is it Total Recall?

zachboth14 karma

I think Oceans 13 has it beat.

kidneybean153 karma

203 or 860?

zachboth10 karma

Operating Engineer Local 139 out of Wisconsin. I think that's what you're asking

shoe-veneer7 karma

I believe they were asking which side of CT you are from (which the answer appears to be neither). 203 is the area code for the west half of the the state and 860 is the East.

zachboth3 karma

I work across the country and move to different cities for each different project, so I have only lived temporarily in Hartford for this tunnel. Once it is finished, I will return to my home and family in Ohio.


You mentioned explosives, it it similar to Wireline in the oilfield? If not, how do you utilize explosives? (My wife is a Petroleum Engineer and wanted me to ask)

zachboth7 karma

We use dynamite sometimes for side or access tunnels. In the photos in the imgur link you can see photos of a side tunnel on our current project that was made this way. Its the darker photos with rough siding compared to the smooth tunnels that are made with a TBM and concrete segments.