CHAPTER 3: KEY ITS DATA ELEMENTS FOR GOVERNMENT REPORTING SYSTEMS

3.4 USE OF KEY CRASH-RELATED ITS DATA TYPES

The primary source of crash data on vehicle configuration, hazardous materials, and carrier information is the P1512 Data Dictionary (Table 3.2, shown in Appendix B). The TMDD has more limited information on vehicle configuration and hazardous material. Both the TMDD and P1512 Data Dictionary have information on injury severity.

As noted in Table 3.2, most of the relevant data from the P1512 Data Dictionary come from its Part 3, which deals with hazardous materials incidents. For the highway mode, such incidents will almost always involve large trucks, and the data in P1512.3 allow identifying truck configuration to a detailed level. However, what is uncertain is if this level of detail will be available for all trucks involved in crashes or just those carrying hazardous materials. That is, will P1512 messages be used only if hazardous materials are involved. This points to an important issue: while the ITS data dictionaries allow for information useful to government reporting systems, the details of how the data dictionaries are implemented dictate whether or not data will actually be available. In P1512.3, there is a "data frame" (a combination of data elements, otherwise known as a "message") that is established for first responders to identify the basic characteristics of a scene. This data frame is defined as:

DF_ComVehicleHeader
Use: Various key codes about the gross type and condition of the vehicle and cargo and the presence of placard or warning data.
Format:
ComVehicleHeader ::= SEQUENCE {
hasPlacards BOOLEAN OPTIONAL, -- true if the vehicle has visible -- placards or labels or material numbers
hasHazmat BOOLEAN OPTIONAL, -- true if the vehicle has any indication -- of carrying Hazardous goods
hasWaste BOOLEAN OPTIONAL, -- true if the vehicle has any indication -- of carrying waste product goods -- Of the three descriptive flags above a hazardous -- waste hauler would have at least the two of flags, -- hasHazmat and hasWaste, set to true
numOfPowerUnits INTEGER(0..255), -- how many power units are there., -- Set to one for passenger cars, trucks -- with fixed cargo and most semi's -- Set to one for the typical 18 wheel -- semi with one trailer -- Set to number of engines for trains -- and barge haulers -- Set to 255 if unknown
numOfCargoUnits INTEGER(0..255), -- how many cargo carrying units are there., -- Set to zero for passenger cars, -- and trucks with fixed cargo -- Set to 2 for a western double -- Set to one for the typical 18 wheel -- semi with one trailer -- Set to number of containers for -- container shipment by boat / barge -- Set to the number of all cars for -- trains (including non freight cars) -- Set to 254 if the number is greater -- than 254 units -- Set to 255 if unknown -- further information on power units, cargo units, -- cargo and placards can be found in -- other related messages.

The level of detail for vehicle configuration is not as great as for subsequent messages, which presumably would be sent upon further investigation and identification of hazardous material involvement. Although some basic data are available, to be completely useful for government reporting systems, subsequent messages would be required in the data stream.

Another example of this situation is crash injury severity. Most traditional safety databases require information on all involved individuals. The TMDD structure allows for this, but unless an implemented database system actually relates injury severity to individuals is another matter.