Implications of Using Annual Average Daily Traffic in Highway-Rail Grade Crossing Safety Models
Highway-rail grade crossing safety models have been around since at least 1940s. A staple of these models is the annual average daily traffic (AADT), which is a measure of vehicular use of roadways. The main reason for the presence of AADT in safety models is because it is the main contributor to what is termed as “exposure.” This exposure accounts for the state of being subjected to the likelihood of a crash. However, in place of AADT a more relevant measure of exposure at highway-rail grade crossings is the portion of AADT that encounters train traffic— termed (AADT)TC in this paper. This is more suitable because the exposure of motorists to train-involved crashes in the absence of trains is zero. Consideration of the non-relevant portion of AADT (i.e., vehicular traffic when no trains are present) can mask the true picture. Therefore, it is prudent to use (AADT)TC, which amounts to stripping AADT of the non-relevant portion. A case of three crossings is presented that are rank ordered based on predicted crashes calculated by using (AADT)TC and AADT in a crash prediction model that was estimated for this study. Results showed that the use of AADT in place of the more relevant (AADT)TC yielded different rank order results. The recommendation is to use (AADT)TC to minimize the possibility of missing crossings that are deserving of attention and perhaps expenditure of safety-related resources. The paper concludes with comments on how transportation agencies may incorporate (AADT)TC in their comparative assessments and future research needs.
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Supplemental Notes:
- This paper was sponsored by TRB committee AHB60 Highway/Rail Grade Crossings
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Corporate Authors:
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Authors:
- Khattak, Aemal
- Sharma, Anuj
- Luo, Zheng
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Conference:
- Transportation Research Board 91st Annual Meeting
- Location: Washington DC, United States
- Date: 2012-1-22 to 2012-1-26
- Date: 2012
Language
- English
Media Info
- Media Type: Digital/other
- Features: References; Tables;
- Pagination: 9p
- Monograph Title: TRB 91st Annual Meeting Compendium of Papers DVD
Subject/Index Terms
- TRT Terms: Annual average daily traffic; Crash exposure; Highway safety; Railroad grade crossings; Railroad safety; Railroad traffic
- Subject Areas: Highways; Railroads; Safety and Human Factors; I82: Accidents and Transport Infrastructure;
Filing Info
- Accession Number: 01373774
- Record Type: Publication
- Report/Paper Numbers: 12-2549
- Files: TRIS, TRB
- Created Date: Jun 25 2012 2:53PM