Retrotechtacular: New York City’s Secret Computer

Over 750,000 people pass through New York City’s Grand Central Terminal each day. Located in the heart of the city, it’s one of the largest train stations in the world. Its historic significance dates back to 1913, when it opened its doors to the public. At the time, few were aware of the secret computer that sat deep in a sub basement below the hustle and bustle of the city’s busy travelers. Its existence was kept secret all the way into the 1980’s.

Westinghouse had designed a system that would allow authorities to locate a stuck train in a tunnel. There were cords stretched the length of the tunnels. If a train stalled, the operator could reach out and yank on the cord. This would set off an alarm that would alert everyone of the stuck train. The problem being that even though they knew a train was down, they did not know exactly where. And that’s where the computer come in. Westinghouse designed it to calculate where the train was, and write its location on some ticker tape.

So this is the part of the post where we tell you how the computer established where exactly the train breakdown occurred. Although the storyteller in the video is admirably enthusiastic about telling the story, our depth of detail on the engineering that went into this seems nowhere to be found. Let us know in the comments below if you have a source of more information. Or just post your own conjecture on how you would have done it with the early 20th century tech.

The invention of the two way radio made the whole thing obsolete not long after is was built. Never-the-less, it remains intact to this day.

Thanks to [Greg] for the tip!

LEDs Strips Tell You the Trains Aren’t Running

[James] is a frequent user of the London Underground, a subway system that is not immune to breakdowns and delays. He wanted a way to easily tell if any of the trains were being disrupted, and thanks to some LEDs, he now has that information available at a glance without having to check a webpage first.

Inspired by the Blinky Tape project at FT Engineering, [James] thought he could use the same strip of addressable LEDs to display information about the tube. A Raspberry Pi B+ gathers data from the London Underground’s TfL API and does a few calculations on the data. If there is a delay, the LEDs in the corresponding section of the strip will pulse, alerting the user to a problem with just a passing glance.

The project is one of many that displays data about the conditions you’ll find when you step outside the house, without having to look at a computer or smartphone. We recently featured an artistic lamp which displays weather forecasts for 12 hours into the future, and there was an umbrella stand which did the same thing. A lot is possible with LEDs and a good API!

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LEDs Turn This Paper Map into a Tram Tracker

Public transit can be a wonderful thing. It can also be annoying if the trains are running behind schedule. These days, many public transit systems are connected to the Internet. This means you can check if your train will be on time at any moment using a computer or smart phone. [Christoph] wanted to take this concept one step further for the Devlol hackerspace is Linz, Austria, so he built himself an electronic tracking system (Google translate).

[Christoph] started with a printed paper map of the train system. This was placed inside what began as an ordinary picture frame. Then, [Christoph] strung together a series of BulletPixel2 LEDs in parallel. The BulletPixel2 LEDs are 8mm tri-color LEDs that also contain a small controller chip. This allows them to be controlled serially using just one wire. It’s similar to having an RGB LED strip, minus the actual strip. [Christoph] used 50 LEDs when all was said and done. The LEDs were mounted into the photo frame along the three main train lines; red, green, and blue. The color of the LED obviously corresponds to the color of the train line.

The train location data is pulled from the Internet using a Raspberry Pi. The information must be pulled constantly in order to keep the map accurate and up to date. The Raspberry Pi then communicates with an Arduino Uno, which is used to actually control the string of LEDs. The electronics can all be hidden behind the photo frame, out of sight. The final product is a slick “radar” for the local train system.

Retrotechtacular: Building BART


Sometimes it’s fun to take a step back from the normal electronics themes and feature a marvelous engineering project. This week’s Retrotechtacular looks at a pair of videos reporting on the progress of the Bay Area Rapid Transit system. Anyone who’s visited San Francisco will be familiar with the BART system of trains that serve the region. Let’s take a look at what went into building the system almost half a century ago.

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Barometer tells you to take your bike or the train


Before beginning his day, [Richard] needs to decide whether he should ride his bike to work or take the London tube. All the information to make that decision is available on the Internet – the current weather report, and the status of the subway lines and stations he’d be taking. The problem, though, is all these pieces of information are spread out in multiple places. [Richard]’s solution to this was to make a bicycle barometer that pulls data from these places and makes the decision to ride a bike or the tube for him.

[Richard]’s barometer is built around a nanode and an old clock he found at a flea market. The nanode queries the UK’s weather bureau and the London underground’s line and station status. All the variables under consideration are weighted; if it’s snowing, the output is much more likely to decide on the tube than if there was a slight drizzle.

It’s a really cool build that certainly makes a great use of the publicly accessible APIs made available by the London underground. You can check out a video of the barometer after the break.

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Radio built from the London Underground map

We love it when PCB artwork is actually artwork. Here’s one example of a radio whose layout mimics the map of London’s subway system.

The build is for an exhibit at the London Design Museum. They have an artist in residence program which allowed Yuri Suzuki time and resources to undertake the project. He speaks briefly about the concepts behind it in the video after the break.

The top layer of copper, and silk screen was positioned to mirror the subway lines and stops on a traditional transportation map. Major components represent various transfer hubs. In this way he hopes the functioning of the circuit can be followed by a layman in the same way one would plan a trip across town.

This may be a bit more abstract than you’re willing to go with your own projects. But there are certainly other options to spicing you track layout.

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Your mobile phone, now with 100% more RFID

More and more today, it is becoming harder to avoid having some sort of RFID tag in your wallet. [bunnie], of bunnie:studios decided to ease the clutter (and wireless interference) in his wallet by transplanting the RFID chip from one of his subway cards into his mobile phone. Rather than the tedious and possibly impossible task of yanking out the whole antenna, he instead pulled the antenna of a much more accessible wristband with an RFID chip of similar frequency instead. Nothing too technical in this hack, just a great idea and some steady handiwork. We recommend you try this out on a card you haven’t filled yet, just in case.