From What The Wiki?!

The RailRoadDuct is conquered!

WTH happened here? A problem exposes itself on Saturday, dozens of people go brainstorming about a solution, some even go and investigate the site, and on Monday, the problem is solved altogether. There is currently rope in the duct, so that we can pull the fiber through when the time comes.

The whole story of Juerd, juerd's brother and Ernst including pictures on how they conquerered the RailRoadDuct (and almost all the others too!!) in a joint effort with the people on the #whatthehack IRC channel and the WTH Wiki can be found on the DuctConquerors page.

Approx. 30 cm. It may look very dirty, but that's because it is.

Tux can't stand up in it.

Velderseweg side. Can you see the light at the end of the tunnel? I for sure can't...

Other end, where I placed my flashlight.

This is why we're doing this. Note that there's a big dirt wall between the beginning of the duct and the first track too.

If you zoom in on this one, you can see the green dotted line that is the duct. On this picture you can clearly see it's a huge length to cross.

Crossing the RailRoad

For the Big Fibre, there is one big challenge in crossing the railroad. This is such a big and important issue that it needs to be resolved long before the FiberParty, July 16th.

There is a duct, that is meant for water (it's currently dried out) and possibly frogs and rats, but it's small (diameter approx. 30 cm) and the bottom 40% of it is filled with sand. Sound gets through, so it's not blocked, but the straight beam of a laser pointer can't reach the end. It has at least one curve but probably two (horizontally). The length of the thing is probably more than 30 meters, but this is a guess.

The curve and sand combined form a problem.

The camp side of the thing is at 5.34559 E, 51.55699 N, and the other side is at 5.34610 E, 51.55721 N. This combined lets us approximate the length of the narrow tunnel easily:

perl -MGeo::Distance -le'print Geo::Distance->new->distance(
    meter => (5.34559, 51.55699), (5.34610, 51.55721)
)'
42.9178612841988

To be on the safe side, let's assume it's 45 meters long.

Dangers

Before possibilities can be discussed, the dangers must be known. Plan Z is very expensive, and to be avoided because of that.

• Anything that can break, is not an option. Garbage in the duct cannot be dug out (there are four railroad tracks above, with a train passing every minute). This also rules out things like fireworks and most unprofessional air pressure solutions. Besides the problems for laying the fibre, residue rubbish is a danger to the environment, as after the event, this duct will retake its original purpose.

• Because of the curve and the sand, things pushed through will eventually have to deal with enormous force in two directions. Hollow pipes can snap and will then be rendered useless.

As you can understand, we don't have the luxury of trying all the cheap solutions first, because of the dangers described above. For example, yellow PVC piping can break and shatter, and will not hold under the pressure that will be applied to it, destroying the pipe and the entire possibility of using this duct.

It would be great if someone had a ferret, as these animals are small enough and just love walking through dark tunnels, but as it stands, we have no ferret at our disposal. Animal friendly we are, so buying one for this particular purpose is not an option we consider.

Possible solutions

Ask the local planning department

It is crucial to know your enemy. Try to find the official maps of how the tube is supposed to be.

What if the tube is not just that, but two branches of a central gutter or whatever.

They are connected. Sound pings prove this. They may indeed be connected to some central pipe parallel to the tracks.

The gemeente might have detailed maps of this, or prorail or whatever.

This sounds like you're volunteering to arrange the communication! :)

I did have a look and nothing is online. I'm afraid this has to be an inside job, and I'm not an insider.

What about surveying by attaching a pocketlight at right angles at the end of a flexible stick and bring it till the middle. If then you see the sidebeam from the other side, you know the complexity. i.e. only two curves. If not, start to worry a lot.

Radio controlled vehicle

This very probably requires a radio retransmitter/amplifier. Who has the skills and equipment to build one?

Of course, the car has a rope attached to it.

• If the car reaches the end, the rope is used later to pull the fiber through.
• If the car gets stuck, the rope is used to pull the car out.
• note, use a wire to control the car not extra transmitter, more reliable and need a wire anyway, easy todo just extend the antenna of the remote control and glue it to the car (so only 10cm of air to the receiver).

Ferret

Does anyone have a ferret?

Dvorak Contacted the 'frettenopvang loppersum' to ask whether this is feasable and whether they would be able to provide a ferret. Turns out the answer to both questions is yes, and the person in charge is available july the 16th, so this might be an option worth considering.

Professional cable ducts

There may be cabling ducts used by the railway company. But their assistance is hard to get at rates we can afford, so this requires the right connections. If you work for Prorail or RailInfra, or whatever maintains the railroads, or know someone who does, try and find a way to get access to their ducts. It's somewhere around kilometer-sign 43, in Liempde of course.

Professional sewage unclogging

(Expensive) Hire professionals to do this job by propelling something using water pressure (directed backwards, like in jet engines).

Garden hose

(Cheap) Using a garden hose to protect the fiber and to push it through the tunnel, maybe filled with water to get it pushed through, then, after drying, using the nylon string in it to pull the fiber through.

Leafblower

We could try a leaf-blower and very light wire... trying to feed this is on one end, putting on the leaf-blower to blow it throug the tunnel. Maybe attach a small peace of 'piepschuim' or other light foam to make it catch more wind without making it too big'n'heavy. An alternative to the foam would be a small parachute made out of a plastic bag or similar.

To know the feasability, use smoke to see at what spots it exits, probably more than one! The wire could be of kites.

Plan Z: through the tunnel, in the open

(Expensive and problematic)

If everything else fails, we can use the train tunnel that is meant for cyclists. This will require the cable to be put in very strong protective material over a great length, and is thus an expensive solution. We also have no way to secure it to walls or anything. An added problem is that during the event, very probably cars will be driving through this tunnel, and the sidewalk will then be used for evasive manouvres.

Things that won't work

The old Plan A: PVC pipes

This won't work, because there isn't enough space to lay out the pipe parts straight in front of the hole. There is approx. a meter and a half.

Well, yellow PVC turned out to be strong enough after all, with duct tape added to it. And the yellow kind was flexible enough to not need the space.

Gray PVC pipes, added together. This kind of PVC pipe does not shatter or break easily. We can fill the pipe with something (probably a thick power cable) to avoid that it snaps. An arrow head or tennis ball can help pushing the cable through the sand.

This solution either works, or we can retract the pipe and try another one.

Filling the entire duct with water, air or whatever

(Assuming water, but most are applicable to any substance)

Where does the water come from? How is the duct sealed off? How do you know it's water proof? How much water do you need? What will the water do with the sand? Where will you leave the water afterwards?

Flying things, like fireworks or cannonballs

It's not a straight line, so it'll hit a corner and fall down. Even if it were a straight line, the risk of the thing failing in the middle and blocking the duct would be too great. Tying a rope to flying objects doesn't work well either.

Inspecting the tunnel with a Webcam and Flashlights

I don't know how long USB-Cables can get, but what about stabilizing a cable with a webcam in front, bundled with a flashlight, to inspect the tunnel beforhand?

If we could get a USB cable across, the problem would also be solved, because we would then simply tie a rope to the USB cable. Unfortunately, USB extension works only for 5 meters, for some webcams 10 or 15. There's no way to use powered hubs ;)

And how would you move the camera? Perhaps it's better to add the suggestion of using a camera to the RC car idea.

Going *over* the railroad

We could in theory get the fiber over the wires of the railroad. But this will certainly not get the approval of the involved authorities, who will probably have the cable cut within an hour.

Digging just under the tracks

Traffic is high all day, and trains go at full speed here, which is somewhere around 140 km/h. It is very unlikely that we will succeed in digging, and if we would succeed, the dangers for the fiber are too great.