Routing algorithm & Faster vs Shortest preference

I have been posting about a bug in the routing algorithm that adds 60 miles (167 total) to a route from Dahlonega, GA to Chattanooga, TN. If I select the Scenic or No Preference as opposed to Hwy, I the the 108 mile route I had been getting with the previous version. Maybe this is not a bug but a change it the Hwy preference and working as it should. Most of the 60 added miles are 4 lane Hwys or interstate.

I don't think shortest vs fastest preference is working in that I have selected several routes and get the same route no matter if shortest or fastest is selected.

0 Former Member over 14 years ago

PSEABOLT,

It has been fun to reverse engineer the "Highway" preference and how it is effecting the route generation.

Here is my take on it - and I thoroughly expect the Dev Team has already figured it out.

Road Preference has priority over Calculation Mode. The "Highway" pref puts the highest route path weighting on Interstate Highways - to the fault of ignoring the Calculation Mode. That is, Calculation Mode has no effect because Interstate Highways have the highest speed assigned in the map set data so by that weighting, the Shortest is ALWAYS the Fastest and visa versa.

So, the routing path will stay on Interstate Highways as close to your Start Point as possible and it will continue to only route on Interstate Highways until the route is as close as it can get to the End Point before routing onto lower priority Highways.

This is why changing the Calculation Mode of Fastest/Shortest has no effect on the routing calculation as long as Road Preference is set to Highway.

[SARCASM]Interesting but not very useful.[/SARCASM]

Cheers,

0 PSEABOLT over 14 years ago

PSEABOLT,

The "Highway" pref puts the highest route path weighting on Interstate Highways - to the fault of ignoring the Calculation Mode. That is, Calculation Mode has no effect because Interstate Highways have the highest speed assigned in the map set data so by that weighting, the Shortest is ALWAYS the Fastest and visa versa.

So, the routing path will stay on Interstate Highways as close to your Start Point as possible and it will continue to only route on Interstate Highways until the route is as close as it can get to the End Point before routing onto lower priority Highways.

This is why changing the Calculation Mode of Fastest/Shortest has no effect on the routing calculation as long as Road Preference is set to Highway.

[SARCASM]Interesting but not very useful.[/SARCASM]

Cheers,

Thanks for the reply. Garmin's routing is on par with and routing app software I have use, even when compared to web apps but I think the developers will make some major improve in the UI and routing algorithms hopefully before the release of the none bata. With more testing, Calculation Mode does do something but I am not sure just what. The following examples seems to say Highways (ie interstate) are not always the fastest.

In all three example the Route is Dahlonega, GA to Chattanooga, TN and only one item in routing preference changes.

Calculation Mode - Fastest
Road Preference - No Preference
107 Miles - 2:04:17

Calculation Mode - Shortest
Road Preference - No Preference
104 Miles - 2:08:44

Calculation Mode - Fastest
Road Preference - Highways
166 Miles - 2:39:42

Calculation Mode - Shortest
Road Preference - Highways
166 Miles - 2:38:29

Why does fastest or shortest Highways add 30 minutes to my travel time?

0 Former Member over 14 years ago

...Why does fastest or shortest Highways add 30 minutes to my travel time?

Because your state hasn't built enough highways! :)

You are constraining the road types the system can select to use as DRTBYK pointed out above.

0 PSEABOLT over 14 years ago

I understand what you and DrtByk are saying but in my opinion the routing algorithm needs some tweaking. I would think new users could easily check Highways and Fastest Route and be very disappointed in the results. Prior to the beta, I am almost positive BC was not giving such high priority to interstate highways but I have not checked. It looks to me like a better option would be one choice.
Fastest
Shortest
Scenic
Highways - (Interstate a better term)
No Preference - (Call it Standard Route and Make it as close to the default Auto GPS route as possible)

0 Former Member over 14 years ago

PSEABOLT,

Absolutely agree with you that this, "Along-road Routing", feature needs some work. If we get the requested ability to set our own Road type Speed attribute (like MapSrouce has) that would go a long way in helping these issues.

0 Former Member over 14 years ago

... but in my opinion the routing algorithm needs some tweaking. I would think new users could easily check Highways and Fastest Route and be very disappointed in the results. Prior to the beta, I am almost positive BC was not giving such high priority to interstate highways but I have not checked. It looks to me like a better option would be one choice.
Fastest
Shortest
Scenic
Highways - (Interstate a better term)
No Preference - (Call it Standard Route and Make it as close to the default Auto GPS route as possible)

Not being a new user I absolutely abhored the previous scheme because it limited what I could do --- it made me the servant of the machine, if you will.; not what I wanted!

I will grant that a noobie might, just might, suffer some disappointment with his initial BaseCamp routing experience but I would suggest that he would quickly be able to find a combination that worked for his needs, and, having done so, he would also experience a closer connection to the Garmin brand. (Disregarding, of course, the typical jarring disconnect between BaseCamp and the newer units software and interfaces.) Mastery is its own reward.

Also, by having discovered and actually trying to use BaseCamp we are dealing with a different kind of noobie, a non-soccer-mom. Someone who is not so close to being overwhelmed with life's other obligations that they have no time nor idle brain cells left over to learn something new that interests them. This is someone who wants to bend the machine to his will. He needs to have a way to do it.

I would also argue for more discrimination in road types. To me, admittedly an old guy, a highway is a vastly different road than an Interstate Highway, so I would like to see both types represented. Look at a paper map! Additionally I would also like to see dirt roads and toll bridges in the mix of things somewhere I could select to use or avoid.

0 PSEABOLT over 14 years ago

I will grant that a noobie might, just might, suffer some disappointment with his initial BaseCamp routing experience but I would suggest that he would quickly be able to find a combination that worked for his needs, and, having done so, he would also experience a closer connection to the Garmin brand. (Disregarding, of course, the typical jarring disconnect between BaseCamp and the newer units software and interfaces.) Mastery is its own reward.

Mastery may be it own reward but if Garmin is depending on the very small group that post to the BC forum regularly to stay in business, we had better be looking for a new GPS vendor. The iPhone, iPad, soccer mom, RVer, General traveler that Garmin must continue to reach to be successful just want's easy. I was just planning a trip to the Smokies and got a 124 mile route so I decided to check Highways and and BC gave me a 305 miles route up I-75 into SC and back down to the Smokies in NC. All preferences must have reasonable limits and a 170 miles added to a 124 trip is not reasonable for most users. Garmin needs to work on the highway Road Preference, and I think the average user needs a way to select fastest route and get a route that shows the shortest time as measured by BC. They also need a Shortest route that agrees with distances calculated by BC. After several weeks of playing with BC and reading posts, I am happy with BC routing but I want garmin to be very successful and keeping pouring big bucks into BC improvements. Garmin needs BC by default right out of the download to draw a route very close to google maps and be able easily transfer to a garmin GPS. The route really really needs to draw the same path on the GPS. BaseCamp Beta has taken a step backwards when it comes to route uploading to the nuvi series. I am not sure the current line of Nuvi can accept the firmware update required to fix the problem.