Helmut,
For following and travelling on the Alpes stages, you can buy this kind of cards (1cm: 1km), the small roads are indicated so we can easily avoid sometimes congestion.
For stage Embrun- 2 Alpes, you need the 2 maps
n°54: Start and finish
n°53 : Col de la Croix de Fer
After looking at this stage, I think a lot of people will put their car in the valley of Bourg-d'Oisans or in La Grave, then will take their bike, will ride to Lautaret to see the riders and come back on 2 Alpes to see the finishing.
Added: 61 for the Cuneo-Jausiers stage!
Added: I have the map 54 and 61 scanned on a protected website , if you need its to prepare your trips, send me one email address.