Mapmaker TomTom is strengthening its partnership in high-definition mapping with German auto supplier Robert Bosch to advance technology that will be used in autonomous driving projects. The two companies said on Tuesday that they would add new layers of data to their maps.

"By the end of 2015 we want to have new high-precision maps for automated driving for all freeways and freeway-like roads in Germany," said Jan Maarten de Vries, TomTom's vice-president of automotive operations.

TomTom will design the maps while Bosch will help to define the required specifications.

Road coverage will subsequently be extended to the rest of Europe and North America, Bosch said.

Multi-layered high-definition maps are key to efforts to introduce automated driving on freeways from 2020, Bosch board member Dirk Hoheisel said.

The new maps will contain a "localization layer" and a "planning layer" for cars to calculate their position on a road by comparing high-definition map data with that gathered by on-board sensors.

Nokia is also auctioning its mapping service Here and it has attracted interest from German carmakers.