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Revision as of 19:23, 20 September 2013 by Jondrush (talk) (Better Schemes for Removing Duplication)

Information about duplicate city names in the USA.

Duplicate City Name Error

WME will prevent you from adding a city name to a segment if any segments in your state have the same city name, and they are more than a few miles away. The error message “The highlighted road is too far from the city it was added to” will be displayed when you save. This is done to prevent elongated City Smudges in WME and the client.

Waze’s Original Solution

Waze resolved duplicate city names when they launched the map three ways.  When a smaller town was surrounded by a larger township of the same name for instance, the smaller town was identified as Foocity and the larger municipality got the name Greater Foocity Area. When the towns were separated by some distance, Waze would append a counting number behind the name. So you might see Foocity (2) and Foocity (3) on the map in addition to Foocity. Last, Waze would dump the city name altogether, which is one reason you see gaps in the Cities layer.

None of these are elegant solutions. Each state will need to decide on a local solution if they want to clear duplicate names from their state, as there are a wide variety of municipal configurations in the USA.

Better Schemes for Removing Duplication

As long as the city name differs by one character, you will not get the error message. But we don’t recommend kludgey fixes. The best way to clear duplication is to find something unique, but accurate, that identifies a municipality. For instance, if a borough and a township share the same name, rename the township segments to read Foocity Twp. In Pennsylvania, we have several instances of five or more townships sharing the same name. So we append the county name to the city name, Foocity, Countyname, since that is how they are uniquely identified to the state government.

The simplest scheme is to resolve conflicts in this order:

1. If a CDP (Census Designated Place as found on the Census Tract Maps) and a City conflict, append something to the city name, since CDPs don’t have any other appellation.

2. If a well-known city and a lesser city conflict the most well-known keeps the unadorned name.

3. If all else is equal, choose one to keep the original name, and the minimum clear suffix to alter the others.

Changing an Entire City Name

Using mass editing tools to change a city name on all segments is strongly discouraged. The mass editing tools can lead to errors and loss of data. The correct procedure is to contact your Region Coordinator with the old city name, new city name and a permalink of the center of the area. The coordinator will then ask Waze to make the correction in their database. A side benefit of this is any polygons with the old city name will be removed at the same time.

Cities Layer Purpose

Currently, the cities layer in WME is only used to display the city name and polygon on the client and provide a location for client warnings. Some users have speculated that this layer will be used for native address search, but this has never been confirmed by Waze.

City Polygon Creation and Updating

Many of the city polygons were created by Waze at the original map import. They were not visible to editors in early versions of WME.

Waze runs a server process regularly that looks for new roads or road segments with changed city names. If the city name is new, a polygon will be created to cover all the segments with the same name. If a polygon with that name exists, Waze will sometimes expand or contract the polygon to match the new road locations. Experience has shown that many of the older polygons resist changes and remain the same shape no matter what city name you apply to the roads. Waze has never explained this.

City Polygon Removal

Waze runs a server process periodically that removes city polygons if there are no road segments with that name.  Experience has shown that many of the older polygons are not removed by this process. Your Regional Coordinator can request that Waze remove these polygons.