Basecamp cant do math

I tried to plan a route from Ohio To Georgia. Basecamp gave me a 13Hr 51min route. Almost all Interstate...OK so I tried an alternate by adding a waypoint. Basecamp did the new route and says it will be 13hr 11 min. I have "Fastest" selected in options. No other changes were made.

Why does Basecamp think 13hr 51min is faster than 13hr 11 min?

Basecamp does not compare routes.
It takes the waypoints you give it and generates the fastest route it can with the roads it has in the database and the max speed limits it has for those roads.

Odd. I tried the same route with only Brimfield, OH and GNF, Perry, GA as start and end, and it chose your western route as the fastest. When I duplicated it and added shaping points to get it to go via your eastern route, it added 30 min.

I have seen it do this also on occasion, but I think not as much as 5% longer as yours is. I have understood from others who know way more than I, that it does not give you strictly faster at all times, it also includes factors which favor certain types of roads, depending on your activity chosen, and maybe other factors like counting the number of traffic signals, or whatever. Seems a closely guarded secret. Also of course your speeds, if customized, will affect the predicted time and route selection. I have entered higher than default speeds, so for example my BC predicted 11:38 for the western route that yours gave you 13:51.

Bottom line, whenever i suspect a different route might be faster, I always duplicate the route and check it other ways then decide what I want to do from that.

Are you using latest version of BaseCamp? Recently Garmin is simplifying routing algorithms, only main roads are used in long routes. This is a problem in BaseCamp and recent nuvis, see:
https://forums.garmin.com/showthread.php?43441-Bad-quality-of-routing-in-BaseCamp-4-2-1

Good point, Popej, in case there is an algorithm difference, my comparison above was using 4.1.2, not the latest 4.2.1. Don't know what the op was using. Shame that routing in 4.2.1 may have changed for the worse. If a GPS doesn't do a good job routing, then all the other features are pretty much useless. Got to get the fundamentals right. Nobody will buy a Garmin product with Adventures and Trip Planner and Lane Assist etc if it doesn't route well.

Interesting example. I’m using BaseCamp 4.2.1 but a different map version and get the shorter western route. I was never able to get the eastern route, but I did get variations.

I played around with the settings and suspect that there is an issue when a section of a road is multiple type. In the US it isn’t uncommon for a section of an interstate to also be a section of a major highway or state highway.

When I set major highway or state highway as a “road type avoidance”, it took the eastern route (via I-77). I didn’t do a detailed check of the routes, but they appear to be follow interstates except for the very beginning and the very end. However, the non-interstate portions were the same in all my routes.

My route time for the western route was quicker, so I suspect you have set custom speeds. It might be that the routing algorithm is using the wrong speed for sections of road that belong to multiple types. It could also be an avoidance issue depending on if you had anything checked or not.

A shot containing the routing dialog along with the speed pop-up might be of use to Garmin should they decide to troubleshoot the issue.

Partial test results

Based on observations I went back and did some controlled testing
Basecamp 4.2.1
Route options reset to default
City Navigator map 2013.3
Brimfield OH > Georgia national Fairgrounds, Perry GA
Basecamp selected the eastern route as fastest with a time of 13Hr 3min
I inserted a waypoint on I75-S that is South of Lexington, KY. I made sure I was selecting the southbound lane
Basecamp selected the new western route as fastest with a time of 12hr 25 min

Changed to City navigator 2013.4 but nothing else. Re calculated the two routs (with and without the I75-S waypoint
Basecamp gave same results with the "fastest route at 13hr 3 min.


The above proves that Garmin algorithms for fastest routing do not correctly find the fastest route. Note the major difference is the different selection on Interstate routing through WV & VA

I will be DL and installing 2014.1 map on this PC and will report back but since the routing calculation is in Basecamp I do not expect any improvement in the results.

More test results and NEW problem

Downloaded 2014.1 City Nav (I use Map-Updater as it allows me to save the new file to PC which Express does not seem to do)

Again ran the two routes from Brimfield to Georga
Again Basecamp decided 13hr 3 min is "faster" than 12hr 25 min but I noticed that when I used just the start & end points Basecamp also decided to not show the total trip time unless I asked for More detail. BUT after adding the I75-S waypoint the total trip time was displayed. I tested this twice.

Maybe Basecamp is ashamed it can't do basic addition so it hides the results it knows are wrong. Yes that must be it as we know Garmin programmers can do basic addition so it must just be a R E A L smart program.
I hope these images show large enough to show you the difference. I had to shring to atach them

2nd picture

In previous year Garmin introduced 2 changes in routing. First is that routing on long distances is simplified and because of this it is faster. City Navigator maps probably are modified to accommodate for this change. Together this can work on new devices but leave problems for all users with old maps or 3-rd party maps. Maybe this is intentional.

Now this change is ported to BaseCamp, where it is easily noticed by users.

Second change is a feature called fastrouting. I think these is a set of preprogrammed routes or main points for routing. Fastrouting is supported by top models, series 3xxx. Nuvi with fastrouting data calculates routes a bit different then without. Problem is that while fastrouting is designed to work with City Navigator it stays active with other maps too, in some cases damaging good routing created by 3-rd party mappers. Well, an indication, that Garmin don't care about maintaining their system coherent.