I'm planning to put a list of the errors detected by mkgmap during map generation on my download page to get more people involved fixing them. Below is the text I'll include in the readme file of the download to ask you for suggestions/improvements on it. Cheers Carlos Readme: This is a short description of the errors listed in the files contained in errors.zip. All these errors can cause routing to fail. For each error listed, ID of the wrong element and a link to download the area into JOSM or view it in a web browser is given. If you want to improve the quality of the maps, please spend some time fixing some of these errors. Roundabouts.txt: Roundabout XXX starts/ends/forks at...: indicates that a way or a set of ways tagged as junction=roundabout is/are not closed or has a portion going out/coming in the roundabout. Flares.txt: this file groups different problems affecting the roads that connect a roundabout with other roads. Arcs.txt: Similar arcs XXX and YYY at...: indicates that XXX and YYY ways are overlapping. Oneway_roads.txt: this file groups different problems affecting oneway roads, going to/coming from nowhere. Turn_restriction.txt: this file groups different problems affecting turn restrictions. Problems can be the lack or excess of any of the turn restriction elements or some of them not connecting. Motorway_exits.txt: motorway_junction nodes must be placed on roads with a ref tag, in order to process them correctly as motorway exits. This file collects those motorway exits positioned on ways lacking ref tag.