In the context of the facilities debate, a key piece of data would be simply car-bike collisions by:
1. occuring on the roadway, outside of any bikeway
2. occuring on bikeways by type - bike lanes, bike paths, sharrows, sidepaths, MUPs (we'd have to flesh this out)
3. total
I think by limiting the scope to car-bike collisions, rather than accidents, we can get more meaningful data in regards to the debate and avoid the problems ILTB mentioned when it comes to identifying severity of injuries. Of course determining if a car-bike collision occured in or out of a bikeway might require more effort, based on how a locality reports it's data.
I think the KISS principle applies - and this data is the simplest we can gather to provide some meat to the facilities debate one way or the other.
Of course this is just my suggestion, I'll do what I can to assist using whatever everyone agrees is the proper format.
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"Let us hope our weapons are never needed --but do not forget what the common people knew when they demanded the Bill of Rights: An armed citizenry is the first defense, the best defense, and the final defense against tyranny. If guns are outlawed, only the government will have guns. Only the police, the secret police, the military, the hired servants of our rulers. Only the government -- and a few outlaws. I intend to be among the outlaws" - Edward Abbey