Route Simulation Speed

Is anybody not under the impression that the 'Simulate Route' feature on a Nuvi shows the simulation at 100% speed?
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  • Heck, I don't have the time or patience if it was 500% speed. I just look at the total route and check detail for any manuevers I have a question about.
  • Yeah, that isn't where I was going with this... but I take it you assume it is 100%?
  • Hmmm. I guess. Slow is slow. I'll vote 100%. I bet you know a trick, huh?
  • Seem like at 100% speed. ( well, at least under speed limit )

    If you check the speedometer, it will maintaine at speed limit, it will even slow down to 9 mph at intersection to simulate turning speed.
  • If you check the speedometer, it will maintaine at speed limit, it will even slow down to 9 mph at intersection to simulate turning speed.
    Getting warmer.... I've got to play with my findings a little bit more, but what I think I found might explain a few things... or at least bring up a whole new set of questions. Stay tuned, I won't keep you hanging much longer.
  • I haven't even done anything with the simulation yet. What is it used for?
  • How the GPS will route you, in real life.
    I agree with Gator, even with 500% like TomTom, it's too slow to wait for. Google Earth's simulation is much better. I usually watch the map, if it looks kind of funny, I'll just take note of the distance & time, hit recalcute and observe the results...
  • Another red circle day! lol
  • What did you mean ?
  • My HP seems to run at 100% speed in simulation mode. That's why I usually choose "flyover" or just look at the route. I don't have time for 100% speed.
  • It's a joke with Uncle Ben and me. We agree so seldom that we circle the calendar date in red when we do. You and I fall under that heading too! LOL
  • So here is what I'm thinking... If simulation speed is indeed 100%--- then I should be able to plan a route from my current position to a point a long ways away, and make note of the estimated travel time.

    Then go into simulation mode, and plan the same route. The time it takes for the simulation to finish should be identical to the time it estimated when it was not in simulation mode.

    I'm going to work with that assumption unless someone can find a flaw in my logic. If that assumption is true, and if we confirm simulation mode is indeed 100%, then I just uncovered some really interesting information about Garmin routes........
  • That their using historical speed data. . .
  • If you check the speedometer, it will maintaine at speed limit, it will even slow down to 9 mph at intersection to simulate turning speed.
    Getting warmer.... I've got to play with my findings a little bit more, but what I think I found might explain a few things... or at least bring up a whole new set of questions. Stay tuned, I won't keep you hanging much longer.
    Max simulation speed is 1 mph below speed limit?
    So maybe you can enable speed warning in Garmin?
  • Max simulation speed is 1 mph below speed limit
    That is what I expected to find, but I don't think I see that in all cases.
    That their using historical speed data. . .
    But if they were... simulation speed would still equal the route transit time estimate, right?
  • I would expect so. I mention it only because the TT v8 map travel estimates and Garmin's are so close to being the same. As for speed warningsn I think I mentioned before that my 760 for a very (!) short time, after one of the firmware updates. flashed what appeared to be overspeed warnings, red glow in the lower left "speed display/trip time" panel.
  • Tim, that must be a pretty long trip you've got plugged in there. So how long are you keeping us in suspense?
  • A little longer... :) You know when I do things I do 'em right. ;)
  • Word on the street. Lol
  • No wonder I'm always late...
  • Simulating a route is not explained properly in the manual (for 780). What is the purpose of this?

    It seems to be running at 100%.

    So if I have a 10 hour trip, does it expect me to sit there the day before staring at my 780 for 10 hrs to see how the trip will pan out?

    Pretty worthless, I say. It should let us select the speed scaling for the simulations.

    Aloke
  • I have a correction: When simulating a trip, using 2009 maps on the 780 (which shows the speed limit os selected roads), I am driving approx 10 mph more than the posted speed limit (like 44 mph on a 35 mph speed limit, 64 mph on a 55 mph road etc).

    I am a speed demon :-)
  • When simulating a trip, ... I am driving approx 10 mph more than the posted speed limit
    Is that how you really drive? Might the GPS be considering a history of driving about 10 MPH over?
  • Tim, you're going to keep us in suspense all Memorial Day weekend, aren't you.
  • No, not really... So why does the Nuvi expect me to drive 74 mph on a road it knows the speed limit is 65?
  • edited May 2008
    I saw another poster mention this earlier today. Not sure. It might explain why my drive time/travel estimates are about dead on traveling major roads. At least in Florida, it's common to exceed the posted speed on Interstates and Turnpikes by at least (!) 5 mph. Are you seeing the same thing on secondary and local roads? Would also explain why users report the travel estimates to be optimistic by 5% or more, as they be strictly observing (or less) the posted speed limits. That raises another issue tho. The TT930 will nearly match the 760 travel time estimates on many routes. Would that also indicate the TT is using historical speeds that exceed the posted limit? Traffic moving at 80mph+ on the interstate rather than the legal 75? I would think so.
  • Probably difficult to say based on regional variances. The TomTom 930 is much more accurate for my time travels now, but the 760 is still way too optimistic.

    I haven't seen the TomTom estimate a speed above the speed limit, but I'll try to see if I can find any examples.
  • If they are truly using user travel data, I can almost guarantee a faster than legal reported speed at least on the stretch of 1-4 betweeen Tampa and Orlando. Also i-75 between Tampa and Ocala. Those would be two ideal highways to target. Also the Interstate east and west of Phoenix. Traffic there was always moving along.
  • I can now find places where the TomTom shows a travel speed that exceeds the posted speed limit.
  • My guess would be either Navteq is reporting historical averages, or Garmin is assuming, which I would think is more unlikely. Unless it's always assuming 9mph over the posted on major highways, which would make it purely a Garmin guesstimate.
  • Unless it's always assuming 9mph over the posted on major highways, which would make it purely a Garmin guesstimate.
    That is what I'm finding... The Garmin reported speed is too consistent over long distances (in my eyes) to really be historical data. I can follow a route on the TomTom and between every intersection on a stable road the estimated speed can vary by +- 4-8 mph, whereas the Garmin will happily go a few dozen miles across many road segments without changing the estimated speed.

    Of course that doesn't rule out the possibility that they could be using historical traffic data which doesn't have nearly the same granularity as the TomTom data.
  • BTW, are some of the TT "illegal" speeds in Florida, which as I remember it was "the scariest place you've ever driven". LOL!
  • I haven't checked out good ol' I4 from Tampa to Orlando yet....

    Imagine police departments purchasing the historical traffic data from the map vendors to find out where people speed the most in their towns...
  • Like they need any more ideas...
  • Here is something I'll add though for clarification. I have yet to find a street on the TomTom 930 where the estimated travel speed for the road exceeds the posted speed limit AND the TomTom is displaying a known speed limit.

    In other words I've seen the estimated speed greater than what I know he speed limit to be on that road, but the map database didn't list the speed limit for that road segment.
  • Of course that doesn't rule out the possibility that they could be using historical traffic data which doesn't have nearly the same granularity as the TomTom data.
    Define "historical data." You seem to be using it in relation to average actual speeds as reported for particular road stretches.

    It could be that Garmin is adapting the history of the actual user. If I were to implement that, I'd keep track of different bins of speed limits (e.g. 0-25, 26-35, 46-55, etc.), and how the user's average speed compares to the speed limit. If the user usually drove 9 over when the speed limit was between 56 and 70, then I'd estimate times based on them going 79 where the speed limit was 70.
  • If they don't use higher than posted on many roads, the estimates won't be as accurate as they should be, nor will routing be as "intelligent".
  • Define "historical data." You seem to be using it in relation to average actual speeds as reported for particular road stretches.
    Correct. The data is collected from a variety of sources, often down to each individual street segment, for each 15 minute period of each day of the week.
  • If they don't use higher than posted on many roads, the estimates won't be as accurate as they should be, nor will routing be as "intelligent".
    Depends on the type of driver you are. :) Personally I agree that they should not base the time estimate of a roue on speeds you cannot legally achieve. (Or at least make that the default setting while giving the user to option to turn it off.)
  • Tho I can't post an example immediately, I imagine there are many somewhat parallel routes across the US and Europe with identical posted speeds, yet on one the speed may be strictly enforced while on the other speeds typically exceed the limit. For those whose time is a premium (isn't that what everyone thinks) the second road would be the one you would want to use in all likelihood. In any case, the quickest route might not be identified, and if so, the travel estimate would probably be incorrect by more than it should be.

    Edit: Anyway, I guess we'll see how TT handles it if and when there speed limit data becomes more complete
  • We are staggering into more of a moral debate than a device quality debate... but I personally don't think the GPS should be enticing us to exceed the speed limit.
  • Conceptually, the Dash is the only current device capable of giving you true "intelligent" routing and accurate travel estimates in a broad range of locations and situations. Consider that minor construction activity on a given road over a period of time will yield slower traffic speeds. In a few months, travel speeds go back to normal after construction is completed. Yet other manufacturers will now have those "slower" speeds embedded in their map, tho they are no longer accurate. The only way to correct the faulty data in your device is buy a new map. Holiday's and local events will also impact the route you should take. None of the other's can take these situations into account. Historical speeds are better than nothing, and likely will be available to all manufacturers within a year, depending on the package they are willing to invest in from the map vendor. But embedded data is going to severely limit how accurate they can become.

    Just my opinion of course.
  • Holidays and local events are something that INRIX has been working on for awhile now. Their "predictive" applications take into account things like local sporting events and concerts where sudden short bursts of traffic will appear. It is just too bad that data isn't making its way down into most GPS devices yet.
  • How do you pause the simulation on a 780?

    How do you start the simulation at any point (that you pick) in the trip?

    By the way, I just got the 780 2 days ago, and I typically drive 5 mph above posted speed limit. I don't think that the 780 is using my personalized travel style to run its simulation.

    Aloke
  • I don't think that the 780 is using my personalized travel style to run its simulation.
    Correct, GPS devices don't do that. (yet)
  • Unless I can pause and start the simulation where I want (on the trip) it is a useless feature, as far as I am concerned. I won't sit through a long trip simulation, staring at the 780 screen.

    Like watching paint dry.
  • I wanted to renew this topic as I just ran across a very interesting thread from another forum. The gist of the question was whether the nuvi's "learned" your driving habits and then adjusted arrival times (and routing?) based on your personal driving habits. One of the posters was quite adamant that Garmin in fact does just that, evidenced by his personal knowledge of the routing algorythm and public patent application. In fact, he said there were 8 classes of road that the nuvi stored actual speeds vs. posted speeds for. One of the "doubting Thomases" noted his travel estimates, then did a hard reset of his nuvi. He posted that the travel estimates did in fact increase afterwards until such time as his nuvi "relearned" his driving habits. (He tended to exceed posted speeds)Didn't know if anyone else here noted anything along this line, or might "volunteer" for a couple of tests. If true, this would also explain a few things with Garmin's accuracy on travel time estimates.
  • My estimated driving time for an hour and a half trip is now the same as the Nuvi 360 was. When I first got the unit, it was estimating 13 minutes faster for the same route. This is strange though as I haven't made the trip up there and I usually drive over the speed limit. Seems like they would have advertised this feature if it really exists. I'm thinking the change in my unit may have come with the firmware update.
  • So shall we propose a test?
  • How would you suggest it be set up? I would think that a new out-of-the-box 7x0 route computation would suffice as a baseline. Perhaps others could then enter the same start/end points and compare travel estimates as well as whether the exact same route is computed. I have read recent posts indicating that common routes seen to change over time, using a different road on a regular basis other than the one originally computed. You set up the test and I'm in.

    EDIT: Just realized this shouldn't be limited to only the 700's. Guess I'll leave this in your hands.
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