OpenStreetMap

Roe Highway/Nicholson Road Intersection

Posted by Helifella on 19 February 2013 in English (English)

Tried to tidy up the Intersection. Have been incorrectly routed through this section by NavFree which is based on these maps. Thought I'd try to tidy it up to fix the problem. We shall see.

Location: Langford, Perth, Australia

Comment from BlueMM on 20 February 2013 at 00:25

It seems to look better, but it looks like you have veered the Nicholson Rd to join it to the on/off-ramp (was up to the bridge), then created a new section of road with same attributes to join to the bridge. I'd leave it as one continuous road until the bridge, then have a motorway_link section for the slip lane off/onto Nicholson Rd to the on/off-ramps. Mainly since Nicholson Rd doesn't veer off to the left to the onramp, it goes straight, but a slip lane veers off (slip-lanes are *_link ways that are determined by the highest level of way it connects to, therefore motorway_link, just like the on/off-ramps).

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Comment from Helifella on 20 February 2013 at 08:34

I see what you're saying there. I went back and made the changes you suggested (I think - does it look better?). It was my first attempt at editing and I've been learning more about best practices as I'm going. My main issue was how to best reflect traffic lights at a dual carriage way. The problem I was facing was how to make it look correct for someone looking at the map, but also correct for routing software. The problem as you are probably aware is that there appears to be two intersections at each end of the bridge. So if you were travelling up the Roe, got off at Nicholson, then turned to go across the bridge you would appear to have to go through two intersections and two sets of lights. To fix this, I pulled the traffic lights for traffic on Nicholson Road back from the intersection coming on to the bridge in both directions. That way, no matter where you are coming from and going to, you will now only see one set of lights as per the real world. It still doesn't solve the problem of the little bit of road in between the intersections at both ends of the bridge though. Really they are not separate at all - they are part of Nicholson Road. Still, hopefully it fixes the routing error I received on my GPS Nav software.

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Comment from BlueMM on 21 February 2013 at 06:55

Hi Helifella, I've cleaned it up a bit more, just a few tweaks, nice job by the way (traffic lights make sense to me - matches the satellite view). Nicholson Rd northbound from the south was a motorway_link for some reason, fixed. There was one on/off ramp slip lane missing, I added & cleaned up the others. Also on/off ramps don't have names or references unless that particular section of road is named (I think only the US names ramps).

Also looks like Nicholson Rd has bike lanes, is that correct? Let me know what you think.

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Comment from Helifella on 28 February 2013 at 02:53

It's definitely much cleaner than it was. Don't know about the bike lanes too much, I've only been through there a few times. I'll have a look when I'm back that way. I guess the approach I was taking to the design of the intersection was to attempt to make it correct not only from how it appears in the real world as much as possible but to also make it appear correct to GPSNav software. Bearing that in mind, the traffic lights are not quite right as navigation software will see them as two separate intersections. E.g. if you going westbound Roe and wanted to turn north on to Nicholson, the GPSNav would think you have to stop at the lights, then go 20m, then turn right at the next set of lights. That is why I pulled the lights back from where the roads intersect. The off ramp missing - do you mean the one going westbound on the Roe turning on to Nicholson going southbound? If so, that was missing because there is no direct lane - you have to stop at the lights to turn left. As to the naming of the offramps, is that a convention that they are not named in Australia or just something that people don't bother doing? I only ask because of the affect on GPSNav. It means when I'm travelling on the Roe and my device is telling me which turnoff to take, it tells me to take "unnamed road" in one km, rather than "Nicholson Road Exit". Not so much a problem when the exits are km's apart but where there is a junction of offramps it is way too easy to take the wrong one.

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Comment from BlueMM on 6 March 2013 at 06:14

I think you're right on the traffic lights, ages ago it was expected that navigation software (or at least the converter from OSM to the navigation format needed) would take care of that, but I see the traffic light tag page has been updated with recommendations of adding lights to where the cars stop. So I have fixed that at the intersection. I see what what you mean about the SE slip lane, I've added traffic lights because you can see in Bing that they have a seperate slip lane but it has lights. Also updated the other slip lanes to be giveways. AFAIK, it's a core principle of OSM to map what's on the ground, not for the renderer or navigation routing software. My take on this over the last 4-5 years is that means on-off ramps shouldn't have names unless there's a sign (like in the US, but also on the M1 in Melbourne). I think it's expected the the OSM to Nav processor/converter will do something smart about on-off ramps so they don't become unnamed road. Maybe file a bug on what ever is doing the conversion? It could automatically generate a message along the lines of eg. "take the exit to Nicholson Road". Also, looking at the Bing sat images, it definitely looks like there are bike lanes along Nicholson Rd, so I added those tags. Feel free to have another look over the intersection to see if I stuffed up anything...

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