In electrical poles the numbering will be some thing like 12/350, 13/350 .. etc., Then it will change to 1/351, 2/352 .. etc. That means the km has changed from 350 to 351 that is 1 km distance travelled. For checking note the time taken from x/350 to x/351 - which is 1 km. For better accuracy use longer range say x/350 to x/355 - note time taken for travelling 5 km.