4 ms·
You are getting lots of comments, but the most obvious reason is that the act of driving on a road degrades it much faster than walking on a sidewalk. Thus, it
by moorhosj 8y ago
You are getting lots of comments, but the most obvious reason is that the act of driving on a road degrades it much faster than walking on a sidewalk. Thus, it needs to be repaired more frequently. Increase the number of cars and the frequency of repair (i.e. costs) increases.