CartoType calculates transcontinental routes on mobile devices in well under a second. It can use mapping data from any source, including OpenStreetMap and ESRI shapefiles.
The route finder can provide the distance, time and cost of a route, based on user-specified criteria including preferred speeds and areas to avoid. You can retrieve all the details of a route, including the length, name, and geometry of all segments, and use these to generate routing instructions. The optional Navigator module can create routing instructions for you and use location fixes from GPS and other sources to perform real-time turn by turn navigation.
Here is a route across densely-populated Southern England from Basingstoke to North London.
Let's zoom in to the start of the route...
...and the end of the route:
What about one-way streets? Here are two versions, eastbound and westbound, of the same route in Central London, showing how CartoType obeys routing restrictions. Arrows show the direction of the one-way streets. The style sheet gives complete control over the appearance of all map symbols, including these.