Can geographical coordinates replace street addresses?

By MUNGAI KIHANYA

The Sunday Nation

Nairobi,

08 July 2023

The address system in Kenya is laughable at best and shambolic at worst. In this country, an address is a box at the post office, while in the rest of the world, it is the location of the house where you live or work. Over the last twenty years, we have been trying to implement the correct method of addresses but have failed; leaving behind the joke of some buildings having three different numbers!

Now that online maps are ubiquitous (nearly everyone has a smartphone), how useful is the traditional address system of numbering buildings? Why not adopt the geographical system of latitudes and longitudes to identify different locations?”, he asks.

The straight answer is ‘yes we can’, but the question is whether it would be convenient to use. The geographical coordinate system subdivides the surface of the earth into degrees of latitude and longitude. One complete circumference has a total of 360 degrees.

The earth has a diameter of about 12,742km, which means that its circumference is about 40,000km. In Kenya, a small plot of land measures about 30ft by 60ft. On a surveyor’s map, this will probably be indicated as 10m by 20m. Therefore, if we are to use the geographical coordinate system, we need to be able to capture that level of accuracy in order to distinguish the smallest properties. That is, we need to work with the diameter of the earth expressed to the nearest 10m, or 0.01km.

Now, 0.01 out of 40,000 is 0.00000025. This is the fraction of 360 degrees that is required; in other words, the coordinates should be to the nearest 0.00009 of one degree – five decimal places.

The popular Google Maps gives coordinates to an accuracy of six decimal places, so this is more than enough. The Nation Centre building, for example is located at 1.2831686 degrees South and 36.8222352 degrees east. That’s quite a mouthful; however, there is shorter method of writing it: (-1.2831686, 36.8222352). Notice the negative sign on the first number. It signifies that this location is to the south of the equator; without it, the coordinates will be for a totally different location, some 285km to the North.

Now which is easier to utter as the location of Nation Centre: “(-1.2831686, 36.8222352)” or “Plot number 20, Kimathi Street, Nairobi”. The first one is 23 words long while the second one is just six words. Still, as explained three years ago (November 2020), there exists a novel system that uses just three words. It hasn’t caught on, unfortunately.