How complicated is a Belgian address? Not that complicated, until you dig deeper and discover the nightmare of inconsistencies.

We often think that to locate a building (in Belgium, but our neighbors experience a very similar situation) we need an address consisting of a street name (which in Dutch ends with “…straat”, “…laan”, “…steenweg”), or which in French begins with “Rue…”, “Avenue…”, “Chaussée…” or a similar prefix/suffix. Then comes a number, even on one side of the street, odd on the other. If we place a building between “10” and “12”, it gets the number “10A”, and if number 10 is a building with several apartments, we differentiate them by “10 Bus 1”, “10 Bus 2” etc. (or 10/1, 10/2, etc.). We also need to specify a municipality along with its four-digit postal code (5 in France). This should allow the postman to find your mailbox without any problem.

Although this is indeed the case for most addresses, unfortunately the reality is often much more complicated. We have mentioned several times that databases can contain information that does not correspond to reality, which can make geocoding difficult. In this article we show that reality is often at odds with common sense! And when a reality is not coherent, it clearly makes data management more difficult.

There are “Guidelines and recommendations for setting up and assigning an address (…)” (Guide – Guide). The problem is that these are not always followed. In addition, most streets and numbers were already assigned before these guidelines were drawn up.

Street names

In French-speaking Belgium, the 10 most important prefixes (in order of appearance: Rue, Chemin, Avenue, Place, Clos, Route, Allée, Chaussée, Ruelle, Impasse) cover only 85% of the (62,000) street names. In the remaining 15%, we see some great classics (Drève: 0.4%, Boulevard: 0.3%, Square: 0.2%), but also countless street names that we would have difficulty distinguishing from a place name. Just over 2000 (3%) street names consist of a single word (e.g. “Dries” in Watermaal-Bosvoorde; not to be confused with “Driesstraat” in Sint-Lambrechts-Woluwe); 1000 begin with a qualifier (e.g. ‘La Chapelle’ and not one of the 160 ‘Rue’ or ‘Avenue de la Chapelle’ or ‘La Chavée’ instead of one of the 35 variants of ‘Rue de la Chavée’). However, these latter cases are strongly discouraged by Article 8 §4 (‘Street names without a street type are strongly discouraged’) of the above-mentioned Directive.

On the Dutch-speaking side (Flanders and Dutch-speaking street names in Brussels), the situation is similar: the top 10 suffixes (street, avenue, path, alley, square, stone street, lane, courtyard, field, mountain) represent only 82% (88,000) of the street names. We then see a large number of names with place names (Dorp, Tuinwijk, Warande, etc.). We have 26 times “Vogelzang” in addition to 35 times “Vogelzangstraat” and one more “Laan” or “Dreef”.

One thing is certain: the 581 Belgian municipalities responsible for naming streets are full of imagination! Not to mention the municipalities that have had the brilliant idea of ​​giving very similar names to intersecting streets: in Bièvre, Rue de la Violette crosses Rue de la Volette; in many Flemish municipalities, Berkenlaan crosses Beukenlaan; in Raeren, Burgstrasse continues Bergstrasse. And if we look at streets that are close to each other but do not necessarily intersect, we have Ange/Angle (Charleroi), Carrière/Barrière (Serain), Ateliers/Bateliers (Châtelet), Beek/Beuk (Ternat), Hekel/Herel (Aalter), etc.
So write neatly on your envelopes – the postman will thank you! It’s no longer a surprise if the delivery person (or worse, the ambulance!) arrives on the wrong street every now and then…

However, the Directive on address allocation requires avoiding “streets whose names differ by only one letter” (8§5).

We even see a particularly interesting situation: in Charleroi, the right side of a street (Rue de Monseau) does not have the same name as the left side (Rue des chèvres)! Although the decision to standardise has been taken, it will certainly take several months or years before the cartographic and official data are aligned.

House numbers

Unfortunately, there is no standard for numbering houses on a street. Often a distinction is made between the house number (called “house number” in the policy, which mostly refers to the entrance to the building) and the “box number” (which refers to the floor, wing, block, etc.). . If an address contains a “5A”, it is not possible to know whether it is a house built next to number 5 (in this case number = 5A) or apartment A of number, unless you are on site or know the location 5 (number = 5, bus = A). The same goes for 5/1. In other words, we do not know whether 5, 5A or 5/1 indicates the entrance to the building. There are many situations where a walled enclosure is built instead of a house. How the new houses are numbered depends on the goodwill and imagination of the municipality:

• At Clos du Manoir 13 in Limal, the new houses are numbered 13/1, 13/2, …, 13/17. There is no bus number, the “/x” is an integral part of the number and not the bus.
• The number 1517 of the Waveversesteenweg in Ouderghem chose the letters 1517A, 1517B… to 1517P
• At Dieweg 54, Ukkel decided that the twenty or so new houses would have the same house number but a bus number between 1 and 20.

Note that the number/bus distribution presented here is that of BeSt Address, which aggregates the official information from municipalities (not without quality issues though, we’ll come back to that in a later article), but it does not always correspond to the distribution provided by geocoders such as OpenStreetMap, Here WeGo or Google Maps.

But the lack of coherence does not end there: In addition to number 10, you can find 10 A, 10/2, but also 10 bis. And if you add 10 to its neighbor 12, the whole is often called 10/12 (or 10-12).

It is therefore not possible in all cases to correctly split (or split) an unstructured (or poorly structured) address. analyze) into “number” and “bus” unless you know the correct format of each address.

In the BeSt address data, we can see the format of the house numbers by examining the “mask”, which consists of replacing each series of numbers with a 0 and each letter with an A. The “0” mask (1 , 12, 1977, …) covers 92.6% of the addresses and “0A” (1A, 5B, 23C …) 7%. In Brussels and Flanders, there are 5 different masks. For Wallonia… 73! However, it can be assumed that in many cases this is due to data quality problems.

Even worse is the lack of uniformity in bus numbers: there are more than 400 different sizes! Among them are 17,000 bus numbers consisting of one letter, which are difficult to distinguish from the house numbers in the format “0A” mentioned above.

According to the guideline (16§4), a number extension must theoretically be indicated with a capital letter immediately after the number (10A, not 10/2, 10 bis or 10 A) and a bus number must be numeric (19§ 6 and §7). However, this is clearly not supported by the facts. We find that 99.6% of BeSt Address house numbers are compliant with these guidelines, but only 69.8% of bus numbers are.

Aside from the name aspect, the placement of numbers is not always consistent. Although even numbers are often on one side of the street and odd numbers on the other, they do not always face the same direction.

For example, Rue François Michoel in Jalhay has only even numbers, with ascending numbers on one side and descending numbers on the other (see image above, where the blue line follows the numbers in ascending order. Based on data from Best Address, with OpenStreetMap as background map). This arrangement is also found in certain closed areas, such as Drève de Trévires in Wavre or Henri Wautierlaan in Saintes.

We can also mention the Dennenhof in Tessenderlo, a street consisting of several ‘sectors’, including one with the numbers 2, 4, 6, … and another with 2A, 4A, 6A, 8A … 8A not between numbers 8 and 10, but between numbers 6A and 8A (the same applies to the Begijnenwinning in the same municipality).

The situation is even more complex in houses with chalets or caravans: in the Tulderbos (Ravels) the numbers seem to have been drawn completely at random (see opposite)… poor postman!

Postal code and municipality

As described in a previous article, at the time of writing, Belgium consists of 581 municipalities, each of which consists of one or more sub-municipalities. Each sub-municipality has its own postal code, but this can be the same for each sub-municipality of the same municipality, different for each sub-municipality, or a mixture of both. A postal code can thus be assigned to a municipality or its sub-municipalities.

However, there are some variations in the Brussels-Capital Region. It is made up of 19 municipalities, 18 of which have no sub-municipalities and one (Brussels City) has four (Brussels, Laeken, Haren and Neder-over-Hembeek). In practice, however, the municipality of Sint-Gillis is called both “1060 Sint-Gillis” and “1060 Brussels” like all other Brussels municipalities. In no other region of Belgium is a municipality referred to by its province or district. Elsewhere, a municipality is indicated by combining the postal code with the name of the sub-municipality (1301 Bierges) or with the name of the municipality (1301 Wavre).

In addition, during the 19th century, the municipality of Brussels-City (or the City of Brussels) took over a number of territories of neighbouring municipalities, which therefore came under the jurisdiction of the City of Brussels, but whose postal code, that of the original municipality, remained in place. For example, most of the territory belonging to the City of Brussels falls under the postal codes 1000 (in blue on the map), 1020, 1120 and 1130 (the 4 sub-municipalities), part falls under 1040 (European district, in green) and part under 1050 (Louizalaan and Franklin Rooseveltlaan, in grey). Etterbeek therefore does not own the entire area of ​​1040 (only the brown part), and Ixelles does not manage the entire area of ​​1050 (only the turquoise part, divided in two by Avenue Louise).

Diploma

Smals Research invests a lot of time in raising awareness of the complexity of keeping data relevant to the real world, both in this blog and in our projects and tasks. In this article we illustrate that reality is sometimes fundamentally complicated by the fact that the nomenclature (municipality names, street names, numbering) is left to the freedom of each municipality with few restrictions. This leads to the inconsistencies described here. Add to this the historical developments and it is easy to send the fire brigade to the wrong address!

This post is a contribution by Vandy Berten, specializing in data science at Smals Research. This article is written under his own name and in no way reflects the views of Smals.