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Effectiveness using random effects generalized models with nonlinearizing link functions
University of Central Florida.
University of Central Florida.
2018 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Generally, a crash modification factor (CMF) estimates the expected changes in crash frequency after a specific treatment is implemented on a roadway. This study assessed the safety effectiveness of implementation of bicycle lanes with different widths in reducing crashes on roadway segments through estimation of CMFs using the cross-sectional method. The cross-sectional method requires the development of safety performance functions (SPFs) for development of CMFs. The most common type of SPFs has been a generalized linear model (GLM) with negative binomial (NB) distribution. On the other hand, the CMFs developed from GLM cannot account for nonlinear effects of the treatments and the unobserved heterogeneity issue. For this reason, this study applied a random effects generalized nonlinear model (REGNM) to evaluate the effects of bicycle lanes. In order to apply the GNM, estimation of nonlinearizing link function is required. The RE models can overcome the unobserved heterogeneity issue by introducing random variations for specific effects.The results of this paper indicated that bicycle lanes are safety effective to reduce all types and bicycle-related crashes in general. In particular, implementation of bicycle lanes with 5ft to 6ft is the most safety effective in reducing all types of crashes and bicycle lanes with 6ft to 7ft were found to be more appropriate to be installed to reduce bicycle-related crashes. It was found that the REGNMs show the most reliable estimates due to its strength to account for both nonlinearity and unobserved heterogeneity issues. From the results from this paper, it can be recommended to have more specific guidance on the minimum bicycle lane widths based on the empirical evidence on traffic safety considering various roadway characteristics, traffic flows, and roadway types. Also, an application of REGNMs in developing SPF and CMF can be suggested for more reliable predictions.

Place, publisher, year, edition, pages
Linköping: Statens väg- och transportforskningsinstitut, 2018.
Research subject
X RSXC
Identifiers
URN: urn:nbn:se:vti:diva-12988OAI: oai:DiVA.org:vti-12988DiVA, id: diva2:1205440
Conference
18th International Conference Road Safety on Five Continents (RS5C 2018), Jeju Island, South Korea, May 16-18, 2018
Available from: 2018-05-16 Created: 2018-05-14 Last updated: 2018-05-25Bibliographically approved

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CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf