How do they build tunnels underwater?

I was driving to Baltimore, through the Harbor Tunnel, when I wondered this: how in the world do they build tunnels, with electricity, underwater? So I did a little research.

It turns out tunnels beat out bridges for maintenance, security, weight capacity and distance capacity.

Many older tunnels were built by boring into the rock and earth underneath the water, but the Turkish Marmaray Tunnel, opened in 2013, was assembled underwater, piece by piece. It cost $3.3 billion to build. The engineers chose this method because it better suited the seismic activity in the region, but it’s an increasingly popular method for building underwater tunnels.

When engineers bore into the earth underneath the water to build tunnels, they have to worry about water breaking in to the tunnel they are building. They use a tunneling shield, which slowly moves forward as the people dig through the earth. Yes, people – as in, manual labor. There is a tool called a tunnel boring machine, but it’s immensely expensive and prone to breaking. The shield was inspired by a shipworm, which is in the saltwater clam species.

Tunneling shield, copyright

The tunneling shield was inspired by the shipworm, drawn above. Image copyright

But when building immersion tunnels like the Marmaray, engineers don’t have to bore into the rock at all. HowStuffWorks explains it so well that I’m just going to quote them here:

To make each tunnel segment, workers assemble 30,000 tons of steel and concrete — enough for a 10-story apartment building — in a massive mold, then allow the concrete to cure for nearly a month. The molds contain the tunnel’s floor, walls and ceiling, and are initially capped at the ends to keep them watertight as they are transported out to sea.Once over the pre-dug sea trench, each tunnel section is flooded enough to allow it to sink. A crane slowly lowers the section into position while divers guide it precisely to its GPS coordinates. As each new section connects to its predecessor, a massive rubber piece on its end squeezes and distends to establish a seal. Crews then remove the bulkhead seals and pump out the remaining water. Once the entire tunnel is built, it is buried under backfill and possibly covered with rock armor.

Still, I was curious exactly how the Baltimore Harbor Tunnel came to be, so I did a little more research. In the 1940s, a federal official reportedly called Baltimore the WORST city in the entire USA, as far as traffic was concerned (take that, Manhattan!). So the Tunnel’s opening in 1957 was a major event, because Baltimore was the only route to get from Philadelphia to destinations south. The Tunnel eliminated 51 traffic signals in downtown Baltimore, and reduced a 45-minute drive through the city to 20 minutes. The Baltimore Sun excitedly reported that locals could look forward to not longer getting abused by, “battalions of outlanders whose only acquaintance with the city has been in its capacity as a bottleneck.”

(Incidentally, did you ever imagine that a publication called Toll Road News, to disseminate “news from and about the world of surface transportation tolling” existed??).

It took over two years to build the Harbor Tunnel, and supposedly it cost $130 million to build, with a $14 million financing cost. It was built using the immersion method – they pre-dug a trench underwater and sunk each piece of the tunnel. Each of the 21 sections is 300 feet long! When it opened, the tolls cost 40 cents for cars and 80 cents for trucks. According to the Bureau of Labor Statistics, 40 cents in 1950 is the equivalent of $3.93 today, Since it costs about $4 for cars to go through the Tunnel, the cost hasn’t really risen in the past 65 years!

Another big issue the engineers faced in designing the Tunnel was how to keep the carbon monoxide from building up inside of it, and how to pump in fresh air. So they designed ventilation systems at each end where the Tunnel meets land, and the CO2 levels inside the Tunnel are monitored 24/7.

So there’s a bit of history and some random interesting facts.


June, 1837

I badly miss regularly writing on this blog – I started it as an outlet, to encourage myself to be intellectually creative, and now I find that I really miss having time to delve into a topic and logic out things for fun. So in the interest of re-connecting, despite something of a time crunch in my life lately, I’ve started digging up some history I have from various projects I did primary source research for. Bit by bit I will carve out more time to explore things in depth, but in the meantime I can amuse myself and others with primary sources and the occasional random science.

The below is an excerpt I found while developing curriculum materials several years back. I should probably save it for Valentine’s Day, but hey, the author didn’t wait for February to express these ideas. And surely we could all use a hopeless romantic sigh during this week of almost-Spring, non-stop rains.

June (no day given), 1837. Pg. 144 of James Bryce’s personal journal
(copied from Curator’s transcription)

“Two weeks ago last Thursday my wife left here on a visit to her parents in Ohio. the first time we have been parted for many days since I first called her my own. and though I was willing. and anxious. she should go from a principle of duty. and from love to her. and to them. still I miss her much. the time hangs so heavy on my hands. at work it is least irksome. for there is employment. and that always gives at least comparative peace. under any circumstances– but when idle I feel her absence most sensibly. then memory is busy and the longing desire to see her again. become almost a painful feeling.

Mysterious (tie??) that gives being and blessedness to married life. a few short years ago. we were nothing to each other. then gradually more and more interested in. and knit to each other by trusting love. until now after more than a year of the most intimate acquaintance with each others characters. I can realize the force of the truth of the Divine ordinance that twain shall become one flesh…other relations of life are near and dear.. but in this. the fountains of hope and happiness of life itself are intermingled. the very being. the views and feelings. the hopes and prospects. the whole character in short. are blended and merged in one–and so must be to enjoy happiness for there is no greater mistake. than to suppose the mere ceremonial of marriage sufficient. or even tolerable. without the union of the heart.”

Percolating Thoughts

Some various thoughts that flow from one to the next:

  1. A PhD candidate in ecology once told me that he didn’t understand how people gained weight from calories. “Isn’t it just energy?” It was a rather startling reminder of just how stratified different fields of science are. I explained that extra energy is stored as fat in the body.
  2. I was listening to a Star Talk Radio episode during my run yesterday and they talked about how you have to have an energy source to make a starship start flying (that is, to overcome the pull of gravity). So I started trying to work out the science of exercise in my head.
  3. I’ve been slowly trying to understand eating for fitness. It’s pretty sad that I’m most comfortable with eating for weight loss, not for supporting physical fitness (though there are definite huge overlaps, since I don’t believe in unsustainable diets).
  4. I had one of those, “Oh wow, evolution is beautiful” moments this morning. Here’s what hit me: Our body is designed to quickly and easily provide that energy we need to overcome inertia/gravity/etc whenever we decide to move. We barely have to think about doing it. This is incredibly basic science, but it was never explained that way in high school. No one ever took our Biology class and our Physics class and said, “Here is a real-life, everyday example that matters for you: do you realize HOW CRAZY IT IS that you can just start walking right now if you want to?” (I could rant for hours about how little of our high school curriculum was made applicable to everyday life, and therefore accessible/relevant enough to really engage us in the subject matter.)
  5. I did a quick Google search and found this website that basically breaks down the whole calories become energy and fat thing and very briefly touches on the Physics of it (the potential energy/kinetic energy that our body uses).
  6. I wonder what the reaction would be if, like in the website above, schools actually taught students how to calculate their calorie needs based on their activity levels. I think it would be tremendously useful and could be done in a healthy way. There is so much misinformation out there, and high school is the perfect age to address it (here’s a really fabulous article about it). We have the information, but it’s getting buried under layers and layers of misinformation and media agendas. And if this isn’t “Biology” and “Physics” and “Chemistry,” then something is wrong with our curriculum.

A PostScript on Epsom Salts

Hypothetically, based on how Epsom salt baths are supposed to work, you should be able to use them preemptively (your body will just store the extra minerals).

So I took an Epsom salts bath last night. Today was CrossFit. I guess we will see if it helps! My muscles were definitely in a much better place than last week, but it’s hard to say whether that’s just me being stronger, a cumulative effect of the foam rolling, or what. When I told someone what we did in class today they said I’m going to be seriously sore for days, so …. we’ll see.

PS – I’m still really bothered that the ONLY research studies to support Epsom salts use are either non-published (which implies it didn’t pass peer review), or too small a group of subjects (only nine!) to really be a valid research population. Why hasn’t someone done a simple blind study where half the people take regular hot baths and half take Epsom salts baths? It wouldn’t bother me as much if Epsom salt usage was something humans have used for thousands of years and discovered through basic experimentation, like many herbs, but this started as a health fad in the 1600s! /rant

PPS – I got all excited telling my friend about all this research I did on Epsom salts, and only realized after that she thought I meant Epsom salts as a laxative! She must have thought I was very unhealthy when I told her that I bought Epsom salts to help me with CrossFit….

Couch Makeover

This was my other big Snow Day project. My past roomie was given this couch by a friend who moved across the country, and it’s super-comfy. She left it when she moved to another state. The cushions got torn up over the last couple months, so I decided to give the couch a makeover. It was a fabulously cheap project – less than $20. I bought remnant fabric – “leftover” fabric that the store sells at reduced prices. The thread and the fabric were on sale, and I had a coupon. I love that kind of shopping!

Because the couch is a pull-out and everything is attached to everything else, it took many hours of hand-sewing, but it’s well worth it!









Spartan Scale

I’m obsessed with the Spartan Races and I’m not ashamed of it.

I’m pretty sure that lifting this cover, with all the snow on top, to put in our recycling qualified as a Spartan-worthy “everyday workout activity” (or maybe just warm-up):


Anyway, when I was gathering the recycling, this saran wrap box caught my eye. You know the little metal tear-off piece? I kept thinking that it would be good for a miniature obstacle course. I let the idea go, but then the saran wrap box fell out while I was picking everything up – so I took it for a sign. After all, the whole goal behind this blog was to encourage my random creative urges – regardless of how silly they are.

I did three obstacles before I ran out of steam: a climbing rope wall, tires, and those ropes you have to go under. The ropes are at the bottom of a hill, but then you do the tires uphill to the climbing wall (it’s hard to see at the angle I photographed it).





It’s pretty silly, but I had fun coming up with ways to recreate the obstacles in miniature with things I had around the house. I used my craft blade to make small slits to fit the climbing wall in, and supported it at the back (though I had fun thinking about participants trying to scale a tilted wall….). I did something similar for the metal pieces (from the saran wrap box) that are holding the ropes.

My only regret is that I don’t have Lego people to put on the course! (Though I’d have to make it much smaller-scale if I did.) The last miniature I remember doing is the sukkah, and I had a lot of fun with that too.

So that’s my silly snow day project before I get down to cleaning.

Recipe: Cornmeal Pancakes

One morning a few years ago, I was craving pancakes but didn’t have any spelt flour. I don’t really like white flour pancakes for whatever reason. But I had been on a cornmeal kick, so I decided to try making pancakes using cornmeal. It turned out to be really easy to come up with a good recipe!


This is really filling – I often make half the recipe. It’s also naturally sweet.


  • 1/2 cup cornmeal
  • pinch of whole wheat flour
  • 1 tsp baking powder
  • 1/2 tsp cinnamon
  • 1/2 mashed banana
  • 1/3 cup almond milk
  • 1/4 – 1/3 cup fruit – diced apple, blueberries, whatever you like


  1. Mix all the dry ingredients together.
  2. Add in the mashed banana and almond milk, and stir well. Gently stir in the fruit.
  3. Let the pancake batter sit for several minutes while you heat your skillet. You know the skillet is hot enough when, if you dash some cold water on it, the water droplets “dance.”
  4. If you are using a non-stick skillet, margarine is optional. If using a regular skillet, melt margarine for frying your pancakes in.
  5. Pour the batter onto your skillet (a full recipe makes two regular-size pancakes). Cook until you see bubbles appear, then flip over and cook on second side.
  6. Serve and enjoy!


I often eat it with a nutbutter sauce, which is super-easy to make.


  • 1 Tbs your favorite nutbutter sauce
  • 1 Tbs almond milk

Beat together with a fork. At first you’re going to think this is crazy, but keep going – you’ll eventually get a creamy sauce.



Approximate Nutrition Info

Pancakes (assuming no margarine) : 324 calories; 3.7g fat; 69g carbs; 6.4g protein

The nutrition info for the nutbutter sauce will vary based on your choice of nutbutter.

Happy Purim

Purim is on March 16, 2014.

I made this video a few years ago in a fit of creative insanity (which is pretty much what Purim is all about). It’s my explanation of the Purim story.

Please note that this video was made in the spirit of Purim – meaning, very tongue in cheek. But it’s pretty true to the text.

Epsom Salts

I started CrossFit training this week. It’s amazing and fun and I had difficulty walking for a few days afterwards! So I walked – slowly – to CVS mid-week to buy Epsom salts. My friend asked me if they really work, which made me curious to research how they work. I suspected the salt was just a carrier for some other chemical that gets dissolved in the bathwater.

I thought this would be a quick project, but I got really into the history research! Here’s what I learned.

For those of you inclined to scroll, here’s the layout of this post:

  • What are Epsom salts?
  • How are Epsom salts made?
  • A Brief-ish History of Epsom Salts
  • The Research on Epsom Salts
  • My Conclusions

What are Epsom salts?

Epsom salt is a compound of two naturally occurring chemicals – magnesium and sulfate. Magnesium and sulfate are both chemicals that help your body run smoothly – especially your bones and joints. The idea is that you absorb the magnesium and sulfate through your skin during an Epsom salts bath.

How are Epsom salts made?

The information I found online was really vague, but here is what I was able to figure out/find:

Magnesium and sulfate can both occur in water. The original “epsom spring” is/was in Epsom, England (more on this below). Originally, people used the waters as is; later, they dissolved the spring water to obtain epsom crystals.

According to the EPA, sulfate occurs naturally in our drinking water, but at small doses (high levels of sulfate can be associated with diarrhea. About 3% of US drinking water has the max recommended level of sulfate [the level at which it affects the taste and smell of the water], but sulfate levels are not regulated by the US government).

Magnesium also naturally occurs in drinking water, but at low levels. In fact, there is concern that many or most Americans may be deficient in magnesium, and there’s some push for magnesium to be added in to our drinking water.

So unless you have a naturally occurring spring with high levels of magnesium sulfate, I would venture to guess that most manufacturers today are producing magnesium sulfate in the laboratory and then infusing salts with it. I saw a few references to using Dolomite crystals, which are made up of magnesium and calcium.

If you’re interested in crystal-growing, the easiest thing is to buy some Epsom salts to start with. Dissolve the salt in the hot water and pour it over a rock in a bowl (that’s the surface for your crystals to grow on). As the water evaporates, the salt will re-crystallize. (source)  Alternatively, you can buy a Dolomite rock for crystal growing.

Dolomite crystals. Image courtesy of

Dolomite crystals. Image courtesy of

A Brief History of Epsom Salts

“… medicine sent from Heaven.”
– Nehemiah Grew, “On the Bitter Cathertic Salt in the Epsom Water” (1695)

The original “epsom spring” was in Epsom, England. In the early 1600s, the story goes, some cows refused to drink from the spring. The local people decided that the waters must be medicinal and began using it for open sores, and in 1645 Lord Dudley North published a book promoting the benefits of Epsom waters for open sores, skin conditions and “melancholy”.

Epsom, England is now known for women cheering at the local Derby. Image courtesy of Zimbio.

Epsom, England is now known for women cheering at the local Derby. Image courtesy of Zimbio.

Epsom quickly became a major tourist draw as hundreds – or even thousands, by some accounts – traveled to use the medicinal waters. In 1695, Nehemiah Grew, a physician and member of the Royal Society, published a treatise on Epsom salts. Dr. Grew may have been the first to extract Epsom salts from the water, and he recommended it for a wide array of maladies, including heartburn, poor appetite, colic, diabetes, jaundice, vertigo and many other conditions. He would flavor it with mace, which is still used today as an anesthetic.

By the early 1700s, the external use of epsom salts and waters was established in the “regular” medical profession. (“Regular medicine” was the term for what we now think of as “Western medicine”.) Retailers would boil Epsom water to get the salt crystals. Physicians would prescribe the salts along with instructions for how much water to dissolve them in. Gauze would be soaked in this solution of dissolved Epsom salts and would be applied for twenty-four hours to the affected skin, or patients would drink the solution. Around 1715, subcutaneous – meaning injected under the skin – application of Epsom salts was slowly came into popularity. Applied subcutaneously, Epsom salts were meant to be an anesthetic, relieving pain.

Still in the early 1700s, a Dr. Hoy figured out how to use sea salt to manufacture Epsom salt crystals, driving down prices and raising accusations of bogus imitation medicine.

The Epsom spring remained popular until the mid-1700s, when sea bathing became the newest health fad. Obviously, Epsom salts survived the ages despite the incoming trends.

Sources: Colonel R. D. Rudolf, “The Use of Epsom Salts, Historically Considered” Canadian Medical Association Journal (1917); A. C. Wootton, Chronicles of pharmacy, Volume 1 (1910).

The Research: Do Epsom Salts Really Work?

At first, this question seemed to lead to a lot of dead ends. I couldn’t find any published studies – I found one study that has never been published where the researchers did find increased blood and urine levels of magnesium and sulfate in subjects who took Epsom baths. But I couldn’t find any research on whether absorbing magnesium sulfate is beneficial, or if it needs to be ingested for our bodies to use it.

Since I’ve been seeing a lot in the blogosphere recently about our bodies absorbing chemicals through skin (ie, from using deodorant), I was really bothered by this. Someone had to have looked into it! So I kept looking, and I found a study published in the European Journal for Neutraceutical Research that looked at cellular increases of magnesium using some “magnesium products” (not Epsom salts, but still based on skin absorption). Not only did this study find increased levels of magnesium, but the researchers claim that skin absorpotion might be better than digesting a supplement because the digestion process destroys some of the supplement. The study looked at a really, really small group of people, so it’s hard to say whether the results are really valid. I also can’t be sure that the results apply to Epsom salts.

My Conclusions: Do Epsom Salts Really Work?

The answer is, unfortunately, that I really don’t know. Obviously I’m not a doctor and you shouldn’t take my advice anyway!

It’s honestly hard to say whether we can go on “historical precedent” or anecdotal evidence here. Yes, a lot of people have used Epsom salts for a long time. Hypothetically, if they did nothing for us, we’d have dropped it completely long ago. But human history doesn’t seem to go that way. It’s not so much that we’re good at tricking ourselves as that our bodies do respond to what we expect to feel.

Do Epsom salt baths hurt you? No (unless you use way too much Epsom salts in your bath – follow the package instructions!).

Has it been scientifically proven that they help you? Not really.

So – my conclusion? We need more research. And I would make the argument that it’s worthwhile research. Anything that people are using as a medical therapy should be seriously researched and understood, and it seems that we would additionally benefit from better understanding the ways that our bodies absorb chemicals and nutrients.

Six Things That Are Absorbed by Osmosis when you’re Jewish

With two Jewish holidays coming (blog posts pending!) I’m thinking generally about the ways that growing up as a Modern Orthodox Jew have shaped my thinking. Every culture teaches you certain implied beliefs about how the world works. Here are ones I identified about Judaism. To different extents, I embrace, reject, or struggle with them.

  1. Wasting food is a moral sin. They don’t tell you about the Eleventh Commandment, but I assure you that when Moses walked down Mount Sinai with those tablets in hand, God’s mother was running after him with a ladle of matza ball soup, upon which was engraved in burning letters: EAT ALL YOUR FOOD, LEST YOU PERISH IN AGONY. I once brought a boy home for dinner and my mother never forgave him for not having seconds.


    Image copyright Avi Katz:

  2. Alcoholism and Overeating are appropriate in context. And that context is mandated by tradition. There is a tradition on Purim to drink until you can no longer remember which guy was the “good guy” and which was the “bad guy” in the Purim story. You have to drink four glasses of wine on Passover – four full glasses. And God help you if you don’t have enough appetite for a proper Jewish meal (see #1).
  3. Gratitude is always appropriate. This isn’t just because you most likely have a Jewish Mother guilting you for every moment of your existence (I love you, Mum, and I promise this is NOT a statement about my childhood!). It’s because we have a blessing – for everything. For going to the bathroom; for eating bread; for washing our hands before eating bread; for new clothes; for waking up in the morning; for going to bed at night; etc, etc, etc.
  4. It’s us against them. Nearly every Jewish holiday has as its premise: They tried to kill us, we won, let’s eat. There’s been an ongoing push-and-shove in the Jewish community since the Civil Rights Movement over how much we should redefine “us” and “them,” and it’s somewhat connected to the struggle to redefine and retain a Jewish identity in a world that is more and more fueled by ideals about equality and working-together-to-save-the-world.
  5. It’s Complicated. Because Jewish law is based in applying written tenets to individual situations, every law was argued over – in depth, extensively, and with numerous case examples. There are loopholes, and loopholes to loopholes, and then periodically the Rabbis would throw out the baby with the bathwater by inserting a story about how God wants humanity to make its own choices and interpretations even if they are wrong. In modern application, what this means is this: we know how to ask a Rabbi a question such that we’re not bound to follow their ruling if we disagree with it. We know how to find Rabbis who will give us the ruling we want to follow. Obviously this doesn’t apply to every situation – we aren’t going to find an Orthodox Rabbi who says, “Sure, go eat pork!” But it applies in quite a lot of other situations. We’ve learned how the Rabbis themselves, in setting down the laws, manipulated and pushed the questions around, and so we know how to do that with their answers too.
  6. We believe in happy endings. One way or another, we’re convinced that we’re heroes of a long, unfolding story. Either the world is going to get so terrible that God gets fed up, destroys everyone, and saves those who are worthy – or humanity as a whole somehow becomes so worthy that the Messianic era begins. Some say that this will be heralded by trumpets and Godly acts; others believe that feminism and the Civil Rights Movement and other examples of the growing equality in society are the beginning of the Messianic era, slowly evolving.

In summary, a Jewish world perspective can be summed up like this:

  1. Aren’t you going to eat that?
  2. I’m pretty sure you should eat that.
  3. Thank god you’re going to eat that.
  4. If you don’t eat that, someone else is going to walk over here and take it from you just like the last time.
  5. I’m pretty sure your doctor would approve of you eating that just this once – it’s a weekday!
  6. You might as well eat it and be happy.