The problem is that there are many thousands of places that can use improvements. Individually they're not necessarily expensive, but collectively the cost woul

The problem is that there are many thousands of places that can use improvements. Individually they're not necessarily expensive, but collectively the cost would be astronomical. Even low hanging fruit sometimes doesn't get fixed in a timely manner. E.g. here's an example: http://www.oregonlive.com/commuting/index.ssf/2014/11/odot_signs_7_million_deal_to_i.html http://www.oregonlive.com/commuting/index.ssf/2014/11/odot_s... I-5 is the primary North-South highway for the US west coast. In Oregon until recently there were numerous stretches without anything separating the traffic other than a grass median. Many cars have crossed the median at high speed, sometimes resulting in fatal crashes. That particular improvement cost $7 million. But, to riff on a comment from the late Senator Dirksen, "$7 million here, $7 million there, pretty soon, you're talking real money."