Beside a number of easy determinable features such as dimensions, weight, size of the display or amount of available memory, there is one important feature of GPS devices that can compute routes, which is difficult to measure: the routing speed = time, that a GPS device requires to calculate a route rsp. to re-calculate a route when the planned route was left.
There is no absolute indication of the routing speed, because it depends on various factors, such as the distance between origin and destination, the available roads, the processor speed and the algorithms used. Therefore we have developed a method to determine the relative routing speed. As described in more details below, we calculated the same route with different GPS devices and measured the required time. We choose the model GARMIN
StreetPilot III as the reference device, which means, the published routing speed tells how much faster a given model calculates the same route than the StreetPilot III. Example: If a model has a routing speed of 5, than it calculates a route five times faster than the StreetPilot III.
Routing speed of various models:
Measuring the routing speed in more details:
In order to determine the routing speed, we have chosen the following routes:
- Bahnhof SBB/ÖBB Sankt Margrethen to Aéroport International de Genève
- Rheinfall bei Neuhausen (Schlössli Wörth) to Lugano Airport
We let a GPS device calculate the fastest and the shortest route three times each and measured the required amount of time. We summed up the average value for each route. Then we calculated the routing speed according to the following formula:
Routing speed = Total time of the StreetPilot III / Total time of the given model
Example: The StreetPilot III requires 506.4 seconds to calculate all four routes, the StreetPilot 2620 requires only 44.9 seconds. According to the formula described above, we compute the routing speed of the StreetPilot 2620 as: 506.4 / 44.9 = 11.27
In other words: The StreetPilot 2620 calculates the same route more than eleven times faster than the StreetPilot III.
Remark: The presented values are accurate for the two arbitrary chosen routes mentioned above. The will vary for other routes. As mentioned before, the routing speed is not an absolutely determinable value, but it gives an idea how much time a particular GPS model may need to calculate a route. The values were measured while the device was not in motion. If you drive while the GPS calculates a route and you leave the planned route, this may cause the unit to start the calculation
over and over again. If there is a long way to go to the destination, the re-calculation may require a significant amount of time. This may lead to a situation, where the GPS never manages to finish the calculation. In such a case, it is very important that the GPS calculates a new route very fast, otherwise you may be forced to stop and to wait, until the unit finishes the route calculation.
b
- GPS receiver off
- GPS device connected to external power supply
- Set to "Better Route" (where applicable)
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