Reply To: Topic: 2 Definitions

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Posted: Jun/07/2016 at 1:48pm – author: dflemons

I think seymourstern may be on to something with the concept of “through travel lanes and … auxiliary lanes”. D16.1 refers to through lanes and turn lanes only descriptively (and, I think, unambiguously) in other definitions but it does not define Total Lanes in Roadway. I don’t believe it should.

I think the inconsistency between FARS and MMUCC stems from those two element sets using exactly the same variable name (Total Lanes in Roadway) to count different things and that can be resolved between the two, outside of D16.1, perhaps by selecting a different name for one variable or the other. Note that no matter what definition is inserted into D16.1, FARS will continue to count what it needs to count. A definition contrary to that end would, at most, only cause a change in the name of the FARS (or MMUCC) variable. But that should be done anyway without adding any definitions to D16.1

On background:

Prior to the addition of so-called PRE-CRASH data collection to FARS, Total Lanes in Roadway counted only the through lanes of a Roadway (one side of a Trafficway, if divided – both sides if undivided). After adopting a PRE-CRASH dataset in 2010 (for crash avoidance studies) Total Lanes in Roadway was moved to the PRE-CRASH set although the definition remained he same.

After gaining some experience with the PRE-CRASH philosophy of data collection, it was recognized that the information required was not the overall configuration of the roadway, in general, but the actual description of the pre-crash environment cross section of the roadway.

This is what is required in this element for this research and what FARS now records. Perhaps it should do so under a different -more specific- variable name.
If any definitions are considered for addition to D16.1, I would think better choices would be more basic terms like “Through Lane(s)”, “Turn Lane(s)”, “Auxiliary Lane(s)”, “Turn Bay”, etc.

Dennis Flemons
Department of Transportation
National Highway Traffic Safety Administration

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