Does the GPS help?

Today I received the following email:

I came across your blog on the net while doing a search from Kenya.

I am a Kenyan who is currently doing annual trips to the country and exploring different regions. This summer my trip was very short and I visited the Tsavo East, Voi region and Lugard Falls.

What I found most interesting in your blog is your use of the GPS. Considering that the road maps available in Kenya are outdated and old in many cases, does the GPS help you in your annual trips? Do you think the GPS routes would have future use in making maps?

I think this is a question of general interest for everybody moving in Africa on unknown routes. Hence my public reply here.

First of all, I've been using GPS (Global Positioning System) receivers, so far all made by Garmin, since they became available, and have gone through three generations of GPS receivers. When travelling in Africa, I would not move a kilometer without having the GPS switched on, if only to document my movements. But the GPS has been extremely useful in several situations.

I currently use a GPS that cannot only record my tracks, but can also load maps and display my position and movement on a map. The only GPS-loadable map I know is Garmin's WorldMap, and I have that loaded on my GPS device.

WorldMap has severe disadvantages. It is rather imprecise with roads often being off by several hundred meters, and it is severely outdated by many years.

On the other hand it has a surprisingly comprehensive coverage of upcountry Kenya, including even many unpaved tracks. Almost all tracks I have driven on are actually in WorldMap, and that is not only because I use it to navigate—I use paper maps as well.

Moreover I have, over the years, collected my own tracks and entered my own waypoints and routes and can now retrace them easily. They nicely complement the WorldMap.

Read more about GPS equipment

The casual traveller on the road

For the casual traveller in Kenya, for example, somebody doing a self-drive safari, the GPS is even more useful when it is already loaded with known routes and tracks that have been used recently. For this purpose I publish my own routes and tracks, apart from general instructions for self-drive safaris. Kenya's upcountry tracks are difficult to follow without a GPS, because there are lots of branches that lead into a private farm or onto a track that's no longer usable. If you just use a paper map, it is easy to miss a turnoff or hit upon the wrong one, particularly if you don't know very precisely where you are.

If, however, you have your GPS attached to your offroad car's windshield and the track or route and a map loaded, you can hardly go wrong. In addition, the GPS calculates your estimated time of arrival, so you know more precisely whether you're at risk of encountering nightfall before you reach your destination. On a day trip any experienced traveller will add two hours buffer time though, because (a) the last part of your trip may be much slower, and (b) you may have to put on your spare wheel.

In addition to these advantages, the GPS will allow you to drive very remote, not well-known tracks that you wouldn't dare to choose without the knowledge that they have been tested and found good recently. Some of the tracks I regularly drive are not even on any map. I found them by trying them on a day with lots of spare time or with the option of camping out, if I wouldn't make it.

Off-road driving

The GPS comes into its own when you drive off-road, usually in a nature reserve. It has at least the following three strengths there.

1. By recording your tracks or, better, loading a good track collection, you are actually building a temporary map and can recognize and re-use your earlier tracks.
2. Once you have a collection of tracks, you can spot nearby tracks on the GPS screen while driving through difficult terrain. When you have to make a decision of whether to continue or turn back, it greatly helps to know that there is a usable track 100 m in front of you.
3. If all else fails and you have to turn back, you can tell the GPS to retrace your track backwards, which guarantees a way out.

More than once I had to use this last feature in Masai Mara, when it was wet enough for a number of creeks to be risky to cross. I drove into difficult terrain on a barely recognizable old car track and ended up in a place from which I could not discern any way out. I had got there by already trying to get out, but a number of times my envisioned escape route proved unpassable, so I had ended up in a situation from which I might not have been able to escape. Due to my chaotic movements I could, of course, not remember the zig-zag way I had come from, but my GPS could. I switched it into trackback mode and zoomed way in, so I could locate my own track to within a few meters precision, then drove all the way back without any further problems.

Without the GPS I would have had to spend at least a night and another day in the bush, I could have been forced to take bigger risks at river crossings, I might have got stuck and could have been forced to walk many kilometers through the bush and high grass. In the very worst case I could have died after running into a dangerous animal.

Flying

If you fly, taking off without a GPS in the cockpit is, in my personal opinion, outright insane. Apart from the security and precision the GPS offers, it can have surprising other advantages, like allowing you to make a precision emergency landing on some airfield.

One nice morning I took off in Samburu for Nairobi in a Cessna 182 (a single-engine, four-seater). After passing Mt. Kenya I got under progressively lower clouds while flying towards Nyeri. The outskirts of the Aberdare mountain range there is hilly and consists of many small valleys, along which one can fly, but without reassurance of being able to continue beyond the end of this valley. I constantly had to check whether I still had enough space to turn back if continuation under ever lower clouds turned out to be impossible. Of course, while following several valleys with only a few kilometers visibility, I would not know exactly where I was without a GPS that kept showing my precise position and track on the map. I could only see a circular area on the ground below me because of hazy conditions under the cloud cover.

Eventually I decided that continuing would be risky and turned back. Without the GPS I would have had to fly a long way back, perhaps to Nanyuki, but the GPS showed me that Mweiga airfield was just a few kilometers to the west. Without the GPS I would not know that and even less found Mweiga without knowing my precise position.

In the eventI turned over towards Mweiga and set up my approach without seeing the airfield. I began to descend and turned into final approach, when the airfield became visible exactly where the GPS showed it, and I could land there without wasting lots of fuel on any detour.

My passengers and I spent a wonderful noon and had lunch at the Aberdare Country Club before returning to the airfield in the afternoon, when the clouds had lifted, and had an uneventful continuation of our flight to Nairobi.

Research

All field research projects I know use GPS receivers to record precise observation locations. The advantage is so obvious that hardly any field researcher will do without one. There are at least three levels of GPS use.

1. The first level of GPS use is to read the coordinates from the GPS receiver and write them down or type them in manually. This is awkward and error-prone.
2. A better method is to do the recording directly in the GPS receiver, for example by putting down a waypoint. Most GPS devices allow to take a waypoint by pressing just one button, but they also allow to add annotations to each waypoint, and many allow to put the waypoint some distance and direction from your current location.

   These recordings can later be offloaded from the GPS into a computer on a daily, weekly, or monthly basis. They can be post-processed in the computer, and they have to be deleted from the GPS, because most suitable GPS receivers have only limited waypoint and track memory. Tracks, if needed, have to be offloaded much more often, because they occupy much more memory than waypoints, because they consist of many trackpoints. Some receivers have adjustable trackpoint density.

3. The next better way of GPS use is through specialized equipment that is pre-programmed to allow other data entry besides automatically or semi-automatically adding GPS positions or tracks. These devices are relatively expensive, particularly the specialized software. Make sure that the software does exactly what you need, because every change is again expensive.

Tracks into maps

I know only one company, Tracks4Africa, that actually makes maps from tracks, and their technology looks good. But I fail to see a viable business model, as they do not provide any incentive to send in tracks. In fact, when I did it, I suffered from the same black hole syndrome I perceive when sending a software problem report to any major software company. I could not find results and particularly could not see the resulting map.

Another project that lets the public audience help to make maps is openstreetmap.org, but that project suffers from its inability to process GPS tracks automatically. It seems to work well in industrialized countries with a high population density and an abundance of high-school kids with a fast Internet connection and too much time on their hands, but I am sure it will not work for the less well-known unpaved tracks in upcountry Africa.

Conclusion

If you plan to travel on unknown paths in Africa, get the best GPS you can afford, learn how to use it, and load all available good information into it before you begin your endeavor. Don't forget a good and tested windshield holder, rechargeable batteries, a good charger, and a computer data cable that allows you to load known and offload your new information.

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