Dijon is a city in France.
A38 West toward Paris
To get to A38 road West in the direction of Paris, take bus number 30 out of the town, pass the lake on your left and get out on a stop called Vaux Bruns. You'll see a wide road to your left with plenty of place for cars to stop.
A31 towards Troyes or Nancy
In order to get to A31 we took Rue de Sully which is in the eastern part of Dijon right besides the "Universite de Burgogne", we went along the university buildings some 200 metres in the direction which leads out of the city towards east, and there was a good spot for hitchhiking.
A31/39/36 to the west/south - towards Lyon or Besancon - Freiburg
to leave the city into one of this directions you may use the crossroad at rue de neuille to get a lift to the first peáge on the motorway which you want to use http://maps.google.de/maps?f=q&hl=de&geocode=&time=&date=&ttype=&q=dijon+rue+de+neuilly&sll=47.302574,5.06135&sspn=0.012165,0.028667&ie=UTF8&ll=47.304145,5.066285&spn=0.012164,0.028667&z=15&om=1