Route calc.

Not until they integrate a crystal ball or an unmanned drone to monitor traffic lights so the PND knows when the light is green or red.

Yes,....I agree. I hate being routed to a state rt with traffic lights especially when there is a highway a short distance away. I think its just a matter of time before we see that enhancement.

Think of how big the dataset would be. Probably much too big to fit on a stock GPS. Also, as above, it would need to be constantly amended.

Way too much work for a company that cannot depend on revenue after the sale.

My own brain does a pretty good job of estimating.

Developing better routing isn't as difficult as it could be. If roads are assigned a value based on the type of road from Interstate/freeway to residential then it would be easier to look at distance weighted by road type. That could easily eliminate the "get off the Interstate and drive 2.3 miles on city streets and get back on the Interstate because the freeway does a loop" which is where we mostly complain. Driving 2 1/2 miles at 60+ vice 2 miles at 35 would show it's faster to do that extra 1/2 mile.

I plan my routes, typically, on mapsource, and download to my GPS. I don't like taking interstates except when they make a lot of sense and prefer backroads, more scenic, less traveled, more relaxing.

The route I select tends to be a blend of fastest and shortest. I would really like more AI built in to allow this kind of route perference blending.

I very much agree with this. I have a destination that the shortest milage is much longer timewise., and the fastest timewise adds 50 miles to the route. I figured out a route that utilizes both on my own. Would be nice to have the GPS figure this stuff out.

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I can carefully adjust my route using the rubber band feature in Mapsource. But my 1490 only looks at start and end points of my route. OK. I add VIA points until my GPS calculates my preferred route. But then JILL announces all the VIA points (three times)even though I am continuing straight down the road.
If Garmin would supply me with a code to selectively mute point announcements, I would appreciate it.

Not to predict traffic lights. Just that for each traffic light or stop sign the GPS should add a preset time delay in route time calculation.

Should not enlarge the map data too much. Just need to add traffic light location in the database. Only a few bytes per traffic light or sign so only a few MB per million traffic lights.

It may be that for those owning a model which supports it (such as the 3790 and many others) that the minimum fuel option routing could be sometimes attractive. If minimum fuel is really done at all close to properly, it should avoid routing you ten miles further on Interstates to save one minute of travel time, and should also avoid routing you down the 25 mph road with a stop sign every 500 feet, just to save a thousand feet of distance.

I have a 3790 showing up at my house tomorrow, and intend to try minimum fuel routing for my things and see how much I like the answer in practice.

Regarding accounting for stopsigns and stoplights--I think the right way to do this is not by annotating every intersection, but rather by adjusting the average expected rate of advance on each significant part of each road to match reality. I think it is a myth that the routing algorithmn works straight from speed limits--as, after all, it computes expected arrival times on routes for which many sections lack a displayable speed limit. So there is in some sense already an expected rate of advance for every road segment.

The sad thing is, I expect the database maker is already trying to do this--so I doubt there is an easy fix likely to roll out soon.

Yep. Have said so myself plenty of times. Shouldn't be very hard to code.

PNDs already do that to some extent, otherwise there would be no point in having a "Fastest Route" option since "Shortest Route" would always win if all roads were treated the same. Also, the "Avoid Freeways" and "Avoid Tolls" options indicate that there is some degree of classification already in place.

In transportation analysis, network models are a bunch of "nodes" that are connected by "links" and each link has "costs" associated with it. Routing algorithms often try to minimize the "cost", which in this case would be time (for "Fastest") or distance (for "Shortest").

But stop lights and stop signs are not in the node, only speed limit.

Why would an exit off a 55 MPH highway to travel 2 miles on a surface street be faster than a 2.2 mile trip using the highway? The flaw is because the surface street route is shorter, it must be faster if you calculate the time/distance using whatever algorithm PNDs use. Travel on a surface street will always average approximately 10 MPH slower than the posted average speed for that segment.

Assume the surface street has segments at 35 and 45 MPH. The average would be close to 40 assuming there were no impediments such as signals or stop signs. The signals/signs will drop the average speed, under ideal conditions to near 30 MPH. It would take around 4 to 5 minutes to travel the 2 miles if you could average close to 30. It would take less than 1 minute to travel the 2/10 mile on the highway. Garmin will route you on the surface street rather than keep you on the highway because of the shorter distance.

Perhaps, over the entire trip, the surface segment would not skew the total time, but in all reality it does affect the total time significantly. From where I live a trip from NW of DC to the Knoxville has me take I-270, I-70, US 340, VA 7 and finally I-81. Staying on I-70 to I-81 adds 7 miles and drops the total time by over 15 minutes but yet with Fastest Time set as the routing preference, it takes secondary roads over the Interstate. The actual time to travel the "preferred" route laid out by my Garmin is closer to 35 minutes more than the estimate vice staying on the Interstate. The sole reason I can ascertain is because the other route is shorter, it must be faster.

That may be true for Garmins, but as I said in another thread my TomTom seems to ABSOLUTELY LOVE freeways and will tell me to take them even if that route is *much* longer than the non-freeway alternative. Of course, "YMMV"....

It is my observation that stop lights are timed based on the time of day. In the morning, they try to get traffic into town in the smoothest flow possible. In the afternoon, they try to get traffic out of town.

Isn't this what traffic and driving trends are for? They remember how you drive on which roads to help provide more realistic driving times.

A little different here, but definitely, the timing varies according to time of day.

My 1490 must have some way to factor in city streets with lights because it's eta is usually very accurate - maybe only a few minutes off if I hit every stop light.

Should Garmin also figure out when the stop light traffic flow is changed from inbound to outbound? Should all the school bus stops and hours be included? Should 2 lane routes that heavy trucks use that have steep grades be included? The list of possible delays on a 2 lane goes on and on ... and on ...

For my dollars spent, all of my Garmins are within minutes of my actual arrival time. That is what the "E" of ETA is, isn't it? If I'm going to stop for fuel and a short rest stop break, I know I have to add the time stopped.

Short of the Garmin being electronically linked to all of the stop lights to know what state it will be in when you actually reach that point in your route, I don't see it changing much. And if it were linked, who is to say you drive at the actual speed to reach the stop light when Garmin calculated you would.

Oh well. Just my few thoughts!

Who knows, at some point in the future our vehicles may be tied into a sophisticated computer network that knows the state of every stop light, crosswalk, etc.. In the meantime, the _average_ effect of some of those possible delays can be included in the speed "cost" for a particular "link" (road segment).

For example, a link may have a posted speed limit of 60km/h, but traffic studies may have shown that the average dwell time at a stop light is 48 seconds. Or, crowd-sourced data from users could indicate that the average net transit speed for that link is actually 52km/h.

Furthermore, these adjustments in effective link speed (cost) can be further tweaked by time-of-day; that's what TomTom's "IQ Routes" feature does:

http://www.tomtom.com/page/iq-routes

Since my ETA is already within minutes of my actual arrival time, I don't really get it. How accurate should a portable GPS ETA have to be for the prices we are paying? How would the GPS know if you are going to be behind a truck going up hill for 5 miles, or not. How would a GPS know if you are going to be behind or in front of a school bus that makes multiple stops on your moring commute?

IQ routing seems to be pretty cool when traveling in strange areas. I wonder at what cost?

Also, when doing Garmin updates you get to chose whether to share your GPS info with Garmin or not. From many response on this site many choose to not share.

My ETA is usually accurate to within 2 minutes, even on 6+ hour trips. I really can't ask for more.

My point was that today's devices already have some significant refinements beyond just using the speed limit (actual or assumed).

Yeah, but watcha gonna do... ? Services like Waze and IQ Routes have to use what they can get. It's the same here at the Factory: some people contribute and others just take a free ride on the contributions of others.

Why?

There were comments back a couple of year ago on sharing info with Garmin. The point made and never debunked was Garmin used some of the data to target ads on their "free" traffic service. Think about it, your unit and its receiver are registered. The data Garmin collects is not disclosed. It could be just crash data or it could be tracks so they know where you travel. IF it includes track data, then the ads displayed could be targeted to businesses that are within your normal travel area. IF it is crash data, then bugs in the software can be documented and turned into features.

@David King,

I think it was discovered that Garmin doesn't download the errors, only tracking info and again, I think, installed POIs selected.

I think it made many users here upset that they didn't try to download and use the device errors to solve problems.

Here is a link to Garmin's download info. It appears to be all about Marketing only.

http://www.garmin.com/garmin/cms/lang/en/site/products/home/...