Waze forum

The HOV wiki entry
I have not read anywhere how to handle HOV lanes that have no define entrance and exit. We have one county that has changed a few of their HOV lanes to allow you to enter or exit when every you want. And other states allowing entrance and exit as long as there is no yellow line... It has been pointed out to me that the wiki states we need to map the HOV lanes.

The HOV lanes that are mapped in southern California are ones with defined entrance and exits. Once everything is setup (TBTL, routing, client) then those lanes would (should) work...

So if a HOV lanes is "free will", then there is no easy way to have the routing engine to work (once it is turned on) for the HOV. I don't think we want to be putting in "ramps" every ??? (100 feet, 1/2 mile, mile, or ???(whatever).) One resolution is a "Lane indicator" or something for the segment to indicate that one of the lanes is HOV (left, right, ???). But we all know that is FAR from now....

I bring this up to help with the wiki understanding of what needs to be mapped for HOV lanes. The HOV wiki page should state that no HOV lanes should be mapped if it is a "free will" lane.

And even if the resolution is low enough to place individual cars reliably in the HOV or regular, if the speeds are different, a speed diference should show in the aggregate data. I'm not mapping the HOV lanes either, but once we can indicate HOV status in the client, then I think this topic will need serious reconsideration.

But given enough data, you don't have to every car plotted in the correct lane to extract some speed difference data from the lanes. I suppose volume discrepancies could overwhelm speed discrepancies. But I would not take the inability of consumer GPS receivers to place a car within a lane width to mean that plotting HOV lanes would be useless. Furthermore, if there is a significant speed difference say between 55-65 mph in the HOV lane and 35-45 in the regular lanes, then we can likely assume that clients that have self identified as HOV are in the HOV lanes. Thus, I continue to think that once a user can self identify as an HOV vehicle, then this topic should be revisited.

AndyPoms wrote:The lane guidance in other GPS units is done essentially by segment - it doesn't actually know what lane you are in, but information about the number lanes on the segment you are on.

Besides at a 95% confidence level, civilian GPS is only accurate to 7.8 meters (just over 25 feet)(1) - and minimum lane width in the US is 12 feet (2) so 25 feet covers two full lanes on either side.

Not entirely true, more devices available today are compliant with the WAAS system for which the above cited stats are the set minimum requirements to be considered compliant with the WAAS specification, but in testing by the NTSB it has proven to consistently provide an accuracy of 1m (3ft, 3 in) or less laterally, accurate enough even for GPS based flights and landings. Many older handset GPS's are not WAAS standard but more and more of the newer ones are are, and external receivers such as the Dual150 Bluetooth receiver are WAAS compliant. This standard is considered sufficiently accurate for aviation uses, as that was the primary reason for the creation of the WAAS system. And since Selective Availability was turned off by the DOD in 2000, even Just plain vanilla GPS measures to greater accuracy than the 7.8 meter minimum requirement for WAAS. Vanilla GPS measures at an accuracy of 2.5 meters. http://en.wikipedia.org/wiki/Wide_Area_ ... ion_System

Currently, everybody gets averaged out.

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jemay wrote:The HOV wiki entry
...
I bring this up to help with the wiki understanding of what needs to be mapped for HOV lanes. The HOV wiki page should state that no HOV lanes should be mapped if it is a "free will" lane.

Wiki Page wrote:As an interim measure, these lanes should be added to the map as separate roads, with the road type as Parking Lot Roads. This means that if you are not currently in one of these lanes the routing will avoid it, but if you choose to get into the lane, the routing will work correctly.

I think something like this needs to be added.

... will work correctly. This should only be applied to dedicated lanes that have exit and entry points.

How will Waze know that the HOV lane that is not a separate road does not have the same traffic delays, and should give a different ETA?

Jim
Level 3 Editor

Because in DC during morning rush hours, the HOV lane was always moving. Couldn't say that about the other lanes. :<)
I posted my previous question because I'm interested in understanding how Waze handles situations where there is a backup in one lane and free flowing traffic in another lane. Does the road configuration or level have anything to do with how the routing algorithm differentiates between these two different traffic patterns on the same road?

Jim
Level 3 Editor

Andy is right!!

@Russblau: the high end accuracy is obtained after 20-30 minutes that the GPS is motionless and only for that specific location. Once the GPS is in motion the accuracy drops dramatically.

The accuracy depends on the combination of the quality of the antenna and the radio. It comes down to how many satellites can be received simultaneously, the processor speed and how long the system stays motionless. Not exactly the best concept for a GPS app using a smartphone GPS.

That said, if Waze can keep track of who is on the HOV/HOT lane then it should be relatively straightforward, maybe not easy.

In response to CBenson's comments, another place where there are speed differences is at stop lights where the wait time is dependent on the direction taken after the light. It becomes even more fun when this intersection is at a freeway exit. Then there can be a multitude of potential directions. With different signal timing and right turn on red.

Jim

AndyPoms wrote:The lane guidance in other GPS units is done essentially by segment - it doesn't actually know what lane you are in, but information about the number lanes on the segment you are on.

Besides at a 95% confidence level, civilian GPS is only accurate to 7.8 meters (just over 25 feet)(1) - and minimum lane width in the US is 12 feet (2) so 25 feet covers two full lanes on either side.

You're a walking Wiki of stats.


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