[OSM-dev] API 0.3 - Map call - Summary

Andy Robinson Andy_J_Robinson at blueyonder.co.uk
Tue Mar 14 17:50:38 GMT 2006

I was thinking about the tram track issue the other day. Clearly the
physical space is common for both the tram and other highway uses. There is
no "physical" separation between each mode of transport across the
right-of-way. In this case I was thinking perhaps its best to have a single
set of line segments forming the feature and then to apply a "tramway" and a
"highway" pair (or more) of Ways.

This approach makes editing and changes much simpler but does not
necessarily address how you would display the final map. The same problem
occurs for any overlapping Ways. How to display.

Taking another example of our street which has 3 separate names or road
number references (eg Baker Street, A00, E11). If a single Way is formed and
the Way given three names then that’s a bit restrictive when the each of
these references applies to a different length of the total continuous Way.

On the other hand, if we create three separate Ways which encompass all of
the segments needed for each how do we display the eventual map. Which Way
has precedence in the display layer order? In some cases this can be dealt
with at a zoom level function, but I'm not so sure it’s a solution to all
requirements, and a tramline and street sharing the same route is a good


Andy Robinson
Andy_J_Robinson at blueyonder.co.uk 

>-----Original Message-----
>From: dev-bounces at openstreetmap.org [mailto:dev-bounces at openstreetmap.org]
>On Behalf Of Frank Mohr
>Sent: 14 March 2006 17:09
>To: Immanuel Scholz; dev at openstreetmap.org
>Subject: Re: [OSM-dev] API 0.3 - Map call - Summary
>Immanuel Scholz wrote:
>> Hi,
>>>1. In JOSM, when a Way is selected only a single Way is displayed in the
>>>"Current Selection" area window, even when there is more than one Way
>>>covering the same set of nodes and segments. Using a "select objects" box
>>>(drag a box over the area) will display both the visible and invisible
>>>This needs addressing as it's very easily to accidentally create a second
>>>Way when the same segments are still selected.
>> I will add support for better visualizing two ways which are on top of
>> each other.
>> However, I don't see a reason to try to forbid any doubled way creation.
>> Ways are logical information and I can think of numerous situations where
>> two ways should be consist of exactly the same line segments. This is a
>> feature, not a bug! ;-)
>right: if you look at
>the road east of the Autobahn A5 is "Karlsruher Straße" and also B3
>and between the crossing in the north and the crossing with the street
>in the center, its also the B426 (that continues to the east.
>>>It's not possible to create a duplicate line segment, but it is currently
>>>possible to create a duplicate Way.
>> Line segments are physical representations of the world, not logical.
>> Since there can only be one physical line between two points, I don't see
>> a reason why someone would want to create two line segments on top of
>> other.
>different "physical lines" like tram trails on the street
>(i placed the tram trails slightly shifted over the street - just as
>they where downloaded from the GPS)
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