As a GPS for surveying we've found the Geonaute Keymaze 500 from Decathlon to be unbeatable. In fact, we carry two of them to get better definition.

For on-foot surveying, and to some extent for in-car, we use a Nikon D40 camera. It's light and takes pictures VERY fast (no need to stop, focus, snap, wait for picture to save, you just point and shoot while you walk). Once home, we use the gpscorrelate program to geotag the photos.

For in-car surveying we've had some limited success recording video with a Canon IXUS 80IS camera. Recording is high quality at about 100 Mbytes/minute, so you can only record about 80 minutes in an 8 Gb memory card, but with good daylight lighting you can read the passing roadsigns and record voice comments.

To adapt OSM maps for the purpose of route planning for car navigation with a minimum degree of trustworthiness would be a project almost as complex as OSM itself, though when OSM matures such a project might become viable (right now there's so much missing content that people don't worry too much about streets going in the wrong direction, or lane counts, or missing road links).

But there's more to maps than just car GPS navigators, and just as you shouldn't trust only Yahoo! Maps or (even worse) Tele Atlas maps in many areas because half of the stuff seems made up (or badly guessed at from aerial photographs), OSM is one more source available for map data. With its strong points (free to use as you please, user surveyed) and its weak points (incompleteness).

In the future, even Tele Atlas will be able to use OSM, and that way hopefully they will get their maps right :-)

He subido las trazas GPX de la 501 para que sirvan de referencia (son del carril derecho), se trace como se trace la calzada :-)

Sí, ya estoy en la lista de correo, pero aún no he recibido ningún mensaje (sólo llevo unos pocos días apuntado).

La separación varía porque varía el ancho de la carretera (para dar cabida a un carril especial de subida en cuesta, por ejemplo). Lo que hay ahora está basado en muchas muchas trazas GPS del mismo recorrido, lo que permite distinguir muy bien por dónde pasa exactamente la carretera real.

Mi duda es cómo conviene colocar las polilíneas, ¿debo intentar mantener la separación constante aunque se ensanche la carretera? ¿debo trazar la mitad de cada calzada? ¿o es mejor trazar el carril derecho, que es desde donde parten las salidas?

En la carretera de La Coruña, que llega a tener diez carriles a la salida de Madrid, parece que trazan los carriles derechos para delimitar el ancho total de la calzada y por eso he trazado la M-501 así. :-)