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Law & Disorder / Civilization & Discontents

How Amsterdam was wired for open access fiber


Preventing fiber damage

As a thought exercise, a scenario had been developed for a catastrophe. Assume that the building where the APOP is located was completely destroyed by an airplane or bomb. What do you do?

As all fibers that terminate in a given APOP are getting close to that location, the number of fibers per meter increases. The main cause of damage to buried fibers is a (sub-) contractor hired for another type of work, for instance on water pipes, who starts to dig with a machine without the mandatory check of the cable plans. A small number of broken fibers can be repaired quite quickly, but it obviously gets difficult as the number increases. A number of precautions were taken to prevent that from happening.

First of all, the number of fibers in one bundle was limited; four bundles of ducts for entering an APOP is common. A separation of one meter between bundles and a cover net 20cm above the bundles reduces the risk of damage by machine digging to multiple bundles. In extreme cases, a shield of concrete was used above the bundles. The design of the network separates out bundles in different directions from the APOP as soon as possible to reduce the potential exposure.

Secondly, the high density fiber cables used did not go over 96 fibers per cable. If an HDPE duct with multiple high density fiber cables is broken, you can use multiple welding teams in parallel, one per cable, which is much faster than one team on a very high density cable.

The SLAs on repairs range from 4 hours for a few fibers to 24 hours for major disruptions with a large number of fibers. In practice this has worked quite well. Very few damages of fiber cables have been reported, and all were in minor branches of the network.


It turns out that given the availability of new electronic equipment, it is quite feasible to construct an emergency APOP and get everything connected again within 6 to 8 weeks. In the meantime, a wireless backup service could be made available using fiber connections from the surrounding FTTH areas. After all, the distances are relatively small.

Getting inside an apartment

The final stretch of the construction was to get the fibers inside a building, build the internal distribution network up to the individual apartment, blow the fiber, do the necessary welding inside the internal distribution box in the basement, mount the connectors and the FTU, and do the required quality control. In some buildings this is a relatively straightforward process, in some it isn’t. But even in the easy buildings, we quickly learned that the process should be improved.

Living in a big city is expensive, so in many cases both partners work. They do not like to have to take time off from work so the contractor can do his work. Therefore, the less time is needed for someone to be home, the better. The more flexible the timing is (early in the morning, lunch time, late afternoon, user selectable appointments), the better.

A distribution box in the basement where you weld the blown fiber from the apartment to the buried fibers is a design that requires a lot of time with someone “at home.” Construct the distribution network, place the minitube, blow the fiber, weld the fiber, test it, weld the connector on the fiber and mount the FTU. During a part of the process the construction workers are in the basement and not inside the apartment, which led to situations where the tenant left his apartment and closed the door.

An improved process uses miniature direct burial cables in the street which are distributed inside the building without any welding, directly to the apartment. This saves a lot of “open door” time. The Genexis CPE with prefabricated fibers and dummy-proof connectors is another example of a design optimized for time.

The really difficult buildings are the ones where you need everyone’s cooperation. If the design of the building leaves you no choice but to get inside each apartment to construct the internal distribution cabling it gets quite difficult. One example is if the utility cabinets are placed inside the apartments. Nicely stacked on top of each other, a piece of cake to drill a hole in the floor to the next cabinet and guide the cable. You only need someone to open the door, and the next one, and the next one.

This can be a showstopper if on the first floor of a 25 story apartment block someone is away on a world tour for six months. Or if someone refuses to open the door or answer calls for no apparent reason.

The original proposal of the general contractor responsible for the deployment seemed like a good idea. Bring all the fibers you will ever need inside an MDU building during the initial digging phase, then build the internal distribution network on-demand. It delays investments and you do not bother people who have yet to decide if they want to take up fiber. Given good preparation, a plan for how to build the internal network, and an agreement with the owner of the building, that should be doable.

Some experimentation showed, however, that the social engineering needed to get everybody’s attention and cooperation should not be diluted over time this way. The results are much better if, directly after the digging, buildings are targeted with the purpose of getting a fiber and an FTU in all apartments in one concentrated effort.

Lessons learned

Deploying FTTH in these kinds of cities with a lot of MDUs, where you have to bury cables and distribute fiber inside buildings, requires a different mindset and approach compared to suburban deployments.

The key to success is an extensive preparation, a detailed design, good organization, and social engineering when dealing with people who live in the MDUs; in fact, this is much more important than trenching and putting in fiber. Only 120,000 meters of trenching was needed for the first 40,000 connections, an average of three meters per connection. Roughly 80 percent of the costs were labor costs, while 10 percent were fiber.

The payoff for the effort is that fiber, once deployed, has proven to be very reliable. So it makes sense not to cut corners and deploy a network that can be used for as many decades as possible.

And yes: houseboats can get fiber-to-the-boat, using a military grade fiber connector.

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