Routing - Difference between 'Minimise Time' v. 'Minimise Distance'

**nail54** · 13th November 2012, 12:36 PM

This may sound like a very basic question but can someone explain what different results would be expected by selecting 'Minimise Distance' v. 'Minimise Time' when setting up a route? In what way is the route calculation expected to be different? .... after all, for example, wouldn't a shorter distance be the shorter time? I use an Oregon and have tried devising routes with both options but am still unable to fathom it. Thanks.

**x-trail** · 13th November 2012, 02:27 PM

Every road category in a map is defined by a speed limit.
When a route is calculated, road category, speed limit, number of turns and road junction are calculated to produce this route.
When you "Minimize Distance" it calculates the shortest possible length of the route, although this can cost you Time because of smaller roads with lower speed limits and more junctions and turns.
When you "Minimize Time" it calculates larger (faster) roads with higher speed limits and takes notice to be the shortest possible (but via larger roads).
If for example, you choose "Minimize Distance" and all the roads are 30 km/h, the length is 30 km, the Time you need is at least an hour.
If you choose "Minimize Time", maybe the length of the route is now 40 km, but via faster roads with 80 km/h speed limits, you need half an hour now.

In the following example in Mapsource Start and Destination are the same.
The purple route is "Shortest Distance" (or "Minimize Distance") and is 30.4 km but it takes 32:25 minutes.
The blue route is "Faster Time" (or "Minimize Time") and it is 1:17 minutes faster but it is also 1.8 km longer.
shorter

**nail54** · 13th November 2012, 03:04 PM

Thanks for your help; like a lot of things, it is of course obvious now that I understand. I did some simulations and you are correct - in my case though it may depend on the vehicle one is driving as to which selection is quicker; for example in my vintage car the shorter 'distance' is always going to be quicker than the shortest 'time' due to the low maximum speed of the car! Therefore your answer has been very helpful.

**tiger555** · 13th November 2012, 04:33 PM

Originally Posted by nail54

This may sound like a very basic question but can someone explain what different results would be expected by selecting 'Minimise Distance' v. 'Minimise Time' when setting up a route? In what way is the route calculation expected to be different? .... after all, for example, wouldn't a shorter distance be the shorter time? I use an Oregon and have tried devising routes with both options but am still unable to fathom it. Thanks.

for example, wouldn't a shorter distance be the shorter time?
Only if: you can travel both routes at equal average speeds.
I think you are over simplifying your analysis.

If you have to have to go someplace from "A" to "B" consider the choices.... for example

Would you rather get from A to B on a faster time route using mostly highway roads where
Route distance = 25 miles
Route time = .5 hrs (30 min)
Your Avg speed = 25 mi/.5 hrs = 50 mph

Or would you rather take a shorter distance (save 5 miles) route using secondary roads with traffic, stoplights, slower speed limits, etc.
Route Distance = 20 miles
Route time = .75 hrs (45 min)
Your Avg speed = 20mi /.75 hrs = 26 mph

Your choice! but there IS a difference based on the GPS selection of roads and their travel properties. In real life I'm sure you've gone out of your way (taken the long way) to save time and avoid traffic congestion.

I personally find that unless I'm familliar with specific patterns in a travel area, that the "Faster Time" setting is generally a much better choice. Your GPS routes are mathematical calculations based on built in road properties. With the possible exception of real time limited traffic information on some GPS models, they have NO situational awareness of the real world of travel.