Best Practice: Turn Segments

[Cory]

Here's a "best practice" question since the help doesn't answer definitively:

At what point does a turn become a "turn segment"?  There are plenty of roads that offer a turn lane, and they rarely get a separate turn segment drawn for them.

However, I came across this today and I am undecided.  It's a turn lane, but it funnels into the same lane as traffic coming directly across the intersection.  If that turn segment is okay, what about the other direction?  Basically it looks "wrong" but I don't know why.  Bonus if you noticed that the "turn segment" is not properly marked as such.

[eg]

I added these two turn segments in my hometown and I think they look okay.

[Saikrishna Arcot]

I suppose that if there is a physical divider between the turning lane and the rest of the road or there is a significant distance between the turning lane and the rest of the road, then you should have a turn segment.

I wouldn't draw a turn segment for that one. The lanes are close enough to keep it as one road. A better example of that (although it's not drawn in) is here.

[IndianaRed]

I don't think you should have started as far back as you did. As you have drawn it, it looks like a divided road but with only one side as one-way. The turn segment should start/end close to the intersection, as it does in reality.

[Cory]

I did NOT draw that.  I saw it and actually thought about deleting it because its just a turn lane with some extra white paint.  There's no room for a merge lane, it just makes the turn.

Personally, I think turn segments should be saved for at least one of the following:

1) the turn is into a dedicated lane (which often implies #3 since you don't have to stop)

2) there is an appreciable geographic separation of the main travel lanes and the turn segment

3) the traffic signs and flow are different for the turn segment

[kalijay]

I saw a couple of "turn segments" already drawn on the map, but weren't labelled as such. If we ignore whether they're necessary at this location or not, and focus on the label, should these be labelled turn segments?

http://www.google.com/mapmaker?gw=39&fid=0x88f671a35aa5d825:0x68225d4f116bfa25

So I went to set the usage to "Turn Segment" and got this reply from a reviewer, "Hi, as this segment of the road is connecting two roads perpendicularly, there will not be any 'Segment Usage' for this road. This is just a normal road I will fix this for you. Here’s a help link http://goo.gl/6BycX for more details on segment usage. Thanks!"

Of course none of the links provided by reviewers ever cover the topic under review. The help pages really need a lot of work.

[IndianaRed]

Cory, I was replying to eg who said that he did add the ones in his post. I agree with your thinking.

[Mara Ww]

Hi Corey,
     I'm having the same kind of problems here, with the further problem that roads will arbitrarily stop and start up again a block or so later. In this one the outside two lanes of Harden St turn into the two different sections of Wheat Street.
http://www.google.com/mapmaker?hl=en&q=Wheat+St.,+Columbia,+SC&gw=30&ll=33.996127,-81.014686&spn=0.000523,0.000849&z=20&vpid=1308964325514&t=h
and there's no left turn into Harden off the western side of Wheat.
    But in the preceding block at the intersection of Harden and Blossom streets both are four lanes.  Note the Map view that still has a cluster of shops around an imaginary plaza (where the well is?) that I've dragged away a number of times.
http://www.google.com/mapmaker?ll=33.997458,-81.015158&spn=0.000523,0.000849&t=h&z=20
     In both cases four lanes turns into two with the outside lanes feeding into side streets much to the surprise of visitors.  And the speed limits on both (now wrong) drop by ten miles.
     Any suggestions?  I'm getting nowhere with moderators

                                                               Thanks,
                                                                 Mara.

--
You received this message because you are subscribed to the "General Map Maker" Google group.
 
- To post a public reply in this same thread:
Reply to this e-mail and your note will soon be posted.
 
- To post a note to the group on a *different* General Map Maker topic:
Visit http://goo.gl/GDnr and click on "New topic"
or
E-mail google-...@googlegroups.com
 
- To unsubscribe from this list:
Send email to
google-mapmak...@googlegroups.com
 
- To see additional useful options:
Visit http://goo.gl/GDnr and click on "Membership."
 
Thanks for using Google Map Maker! :-)

[Cory]

kalijay, It's hard for me to get past the fact that there's really no need for those turn segments.  They don't add any value to the map--the right turn inlet is not really separate from the left turn inlet, and the right turn exit doesn't have its own lane to bypass merging with traffic.  BUT as drawn, they definitely appear to be turn segments--they're not separate roads and they each have a limited direction available.

[Cory]

Mara, they really look drawn correctly to me, but Google Maps doesn't really offer any lane advice.  Maybe someday they'll be more lane detail (lane segments and such) and therefore provide useful lane guidance.

Personally, I'd be afraid that making people use a GPS in place of paying attention to the signs is going to be an issue.  Are there any issues with visibility of the signs?  Or is it just a case of people not paying attention?

[Cory]

I get it now IndianaRed.  I was replying by email and it doesn't show what message is getting replied to.  I agree though... eg's additional segments aren't violating any rules, but to me they imply that I'll be able to make that turn and have my own lane without having to stop or yield.

For instance, in my town, there's a right turn lane that is specifically signed "Do not stop" and provides a lane to keep travelling.  THAT and interstate turn-offs are where I think turn segments should be used.

[Mara Ww]

Cory,  Signs? What signs?  If there are any they were long go hidden by the shrubbery just as (I now realize) some of the lanes are hidden by the historic oaks (many dead). Since these streets are on one of Columbia's historic touring routes, I can live with it.  But a 6 inch high by 18 inch wide divider does not make two parallel roads.  And there's no plaza.

                                                                     Thanks,
                                                                       Mara

                                                                 

On Fri, Jun 24, 2011 at 10:12 PM, Cory <cory....@gmail.com> wrote:

Mara, they really look drawn correctly to me, but Google Maps doesn't really offer any lane advice.  Maybe someday they'll be more lane detail (lane segments and such) and therefore provide useful lane guidance.

Personally, I'd be afraid that making people use a GPS in place of paying attention to the signs is going to be an issue.  Are there any issues with visibility of the signs?  Or is it just a case of people not paying attention?

--

[Nathan Williams]

Mara,  just to back you up, I too agree that a narrow concrete barrier does not justify drawing a street as parallel one-way segments (Hello?  Isn't that what the "physical divider" attribute is for?).  However, after a Google Reviewer told me the other day that such a mapping was justified even for a painted (!) divider (actually, a center-turn lane in that case) I pretty much gave up trying to correct such stupidity.

[Cory McKay]

Using two one-way segments for a road with a center turn lane should be stopped and the edits undone.  Using two segments implies that you cannot make left turns off the road (except at connectors), but the center turn lane is there specifically for that case.  Too many people are trying to make the map into a drawing, instead of drawing a map.

On Thu, Jun 30, 2011 at 11:59, Nathan Williams <wth...@gmail.com> wrote:

Mara,  just to back you up, I too agree that a narrow concrete barrier does not justify drawing a street as parallel one-way segments (Hello?  Isn't that what the "physical divider" attribute is for?).  However, after a Google Reviewer told me the other day that such a mapping was justified even for a painted (!) divider (actually, a center-turn lane in that case) I pretty much gave up trying to correct such stupidity.

--

[Nathan Williams]

The problem was that this wasn't an edit - that's the way this particular segment of road has been mapped for quite some time.  I was attempting to eliminate the two parallel routes and draw one single route down the center where the road actually is, and the reviewer stated that this was incorrect and even implied that he would be extending the dual-carriageway-style of mapping (I don't think he did).

The edit in question is here, if anyone cares: http://goo.gl/J1BpG
This is where the road actually merges together (there is a short section of actual dual-carriageway where US-11 interchanges with VA-37 to the south).  I was attempting to delete the first bit of erroneous road and had already drawn in a the new combined roadway when this interaction took place - the comments pretty much illustrate how frustrated I was with the moderation staff that day (I had already gotten into it with another reviewer over the "legal divider" definition and I was officially done arguing).  I'd be willing to attempt fixing it again, but only if I had about 20 people to back me up. :)

[IndianaRed]

Are left turns not allowed in this area? It seems a lot of the side roads are not connected to the furthest lane.

I had a comment from a reviewer about "legal dividers" which essentially makes them the same as "physical dividers", i.e. no left turns except at a junction. What is the point of separate divider designations if they mean the same thing? Seems Google only wants us to draw single line no-divider, or split lines for any type of divider...

[Nathan Williams]

Left turns are allowed except in the actual divided section, hence why this really needs to be corrected.

Don't get me started on legal dividers.  The way I read the GMM documentation, the definition is clear - a legal divider is a painted line on the roadway, nothing more, nothing less.  Whether turns across traffic are allowed is irrelevant - we're simply making the distinction between an undivided roadway (a residential street, perhaps) and a more high-volume roadway with better safety features.  Yet I've actually had reviewers tell me that a double-yellow line doesn't count as a legal divider, when Google's own screenshot of a legal divider is that of a double-yellow line!  I guess the ability to see is not a requirement to be a GMM moderator.

[Cory McKay]

I'm with you on the confusion concerning legal dividers.

Technically, you're not supposed to make a left turn across a double yellow line, but its not enforced anywhere I know of, and California has a separate law that says you can't cross a yellow divider more than 3 feet wide.

The whole point of the dividers and the separate carriage ways is supposed to be so that when routing you to a destination on the left, the system will know whether to instruct you to make a u-turn and a right, go to the next connector to make a u-turn and a right, or if you can directly make the left turn.

--

[Saikrishna Arcot]

3 things:

1. I can't access the link because I don't have permissions.
2. Is this the resource that moderators use when Denying/Approving edits?
3. For Legal/Physical Divider, in this case, we might need a ruler tool in GMM to measure out 100 m. Also, I am pretty sure this statement wasn't in the Map Maker Guidelines.

[BearRyan]

I've had the same problem with legal dividers that you have had.

[Praneeth]

HI,

@Cory
A 'Turn Segment' is marked in order to avoid a junction. Marking a turn segment would make the routing clear and in choosing the shortest path possible. The turn segment in the link you are refering to looks good. As turn segments are uni-directional it just helps in avoiding congestion at the intersection by routing the traffic before the junction.

@Saikrishna Arcot
Hey my appology for posting the incorrect link here is the correct one.
It is not required for a physical barrier or an open space to be present between the roads to mark a turn segment. A painted line indicating a turn could also be marked as a turn segment. To learn more about 'Turn Segment' you can refer to thisthe help topic: http://www.google.com/support/mapmaker/bin/static.py?page=guide.cs&guide=1094314&topic=1094381&answer=1098062

With reference to the questions regarding the 'Legal/Physical divider' I would like to clarify that if the length of the physical divider is more than 100m, the road needs to split into separate lanes and for a legal barrier having turn restrictions the same would apply. I agree to the view of Cory regarding dividers and the separate carriage ways.I do agree that this information is not yet updated on the help page and we are currently we are working on it.

@Measuring the 'Divider' length.
To measure the divider length you can use the 'Draw a Line' tool and select the option 'Road' and draw a line segment equal to the length of the divider. The length of the of the segment can be seen as we drag one end of the line segment, which could be used to find the length of the divider.

Thanks
Praneeth.  

[Saikrishna Arcot]

Should have thought of that. Thanks for reminding me.

[Cory]

On Tuesday, July 19, 2011 6:58:53 AM UTC-4, Praneeth wrote:

@Cory
A 'Turn Segment' is marked in order to avoid a junction. Marking a turn segment would make the routing clear and in choosing the shortest path possible. The turn segment in the link you are refering to looks good. As turn segments are uni-directional it just helps in avoiding congestion at the intersection by routing the traffic before the junction.

 The "turn segment" mentioned in the original post is not marked as a turn segment.  Shouldn't it be?

[Praneeth]

Hey cory,

You are absolutely correct it should be marked as a 'Turn Segment'.

Thanks
Praneeth