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Federal Highway Administration Research and Technology
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Publication Number: FHWA-HRT-07-046
Date: August 2007
Model Minimum Inventory of Roadway Elements—MMIRE
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DEFINITION OF AND RATIONALE FOR MMIRE
The concept of MMIRE includes a listing of roadway inventory and traffic elements critical to safety management and the proposed coding for each of these critical elements. No such listing now exists. These high-priority inventory and traffic variables are linked to and then used with crash data elements in making decisions concerning implementing safety treatments and in developing knowledge about the safety effects of treatments, roadway designs and traffic operations (e.g., signal phasing). While crash data alone can be used by a State or local roadway safety agency to answer some questions (e.g., the identification of locations for treatment), they are not sufficient in many cases. Without sound inventory and traffic data, the safety professional’s ability to make critical programmatic decisions is greatly reduced. Examples where sound inventory and traffic data are needed include:
Almost all State highway agencies and some local transportation agencies currently have roadway inventory and traffic flow data in their files. These data were often the result of expanding data collection efforts required by FHWA’s Highway Performance Monitoring System (HPMS)6 for sample sections of roadways to the full State system of roadways. Although HPMS has been the driving force behind the collection of roadway inventory and traffic data by State departments of transportation (DOTs), it cannot be considered the model for safety inventory data because:
While the data elements in many States’ current inventory systems are an expansion of the HPMS sample elements to all roads in the full State system and capture such variables as lane width, shoulder width and type, speed limit, and other cross sectional variables, very few State systems capture curvature or grade data, intersection inventory data, roadside inventory data, or other data elements critical to safety.
FHWA and AASHTO initiated efforts to develop a “Draft Model Highway Data Dictionary” for subsequent use in the development of the Transportation Safety Information Management System (TSIMS). The data dictionary is viewed as a starting point for developing a comprehensive, uniform set of roadway characteristic data attributes.7 However, it cannot be considered a model for a sound safety inventory database due to some limitations in the explanatory descriptions of the items, missing critical safety elements (e.g., clear-zone width), and in the classification of the priority of the elements.
In summary, there is no current listing of critical safety-related inventory and traffic data elements––no MMIRE. In contrast, the U.S. Department of Transportation’s (USDOT’s) National Highway Traffic Safety Administration, working with the Governors’ Highway Safety Association and safety data advocates across the Nation, have developed a listing of and definitions for critical crash data elements over the past decade—the Model Minimum Uniform Crash Criteria (MMUCC).8 Although not an official national standard, this data element guideline has become the de facto standard that is used by almost all State agencies when they reexamine and modify their crash report form. What is needed is a companion for MMUCC— thus the birth of MMIRE.
Three final background points are noted concerning what MMIRE is envisioned to be. First, since the development of the concept in the Council and Harkey White Paper,(1) it has been strongly recommended that like MMUCC (but unlike HPMS), the collection of MMIRE elements will be voluntary rather than mandatory. Like MMUCC, MMIRE is envisioned as a tool to be used by State and local agencies in their safety data improvement efforts. The only MMIRE-related requirement currently being discussed concerns States applying for Federal safety-data improvement grants under Section 2006(e)—“State Traffic Safety Information System Improvements” in the new Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU) legislation. The language in that section indicates that the USDOT Secretary will define model data elements for use in safety analyses, and that States applying for the grants will need to certify that they have adopted the model elements or will use the grant funds to work toward adopting and using them. While not known at this time, it is anticipated that elements in MMIRE, like MMUCC, ultimately will be included in the listing of these model data elements.
Second, it also has been recommended strongly from inception that MMIRE efforts be continually reviewed by the data collectors and users—the State and local DOTs. The White Paper(1) suggested that the listing of proposed elements be vetted by review committees of State and local agency safety and inventory engineers and users. The vetting effort should include strong participation from appropriate individuals and committees in AASHTO, because their endorsement and support will be critical to gaining State agency acceptance. As described below, this vetting process has begun with the convening of State and local data experts in a MMIRE review workshop. It is anticipated that FHWA will continue that vetting process in further reviews.
Third, the choice of elements considered for MMIRE and the priority assigned are based on the need for that element in safety efforts. There are clearly other variables collected in HPMS and other files that are used for nonsafety analyses (e.g., pavement depth). These may well be key variables for other purposes, but were not included (or recommended) in MMIRE unless they were felt to be important for safety uses.
Topics: research, safety, data and analysis tools
Keywords: research, safety, safety data, traffic safety information systems, road inventory data, traffic data, data collection
TRT Terms: traffic safety, traffic data, data collection