Description:
The Highway Safety Manual (HSM) was first published by AASHTO in 2010 and provides guidance for safety analysis in highway transportation project planning and development. The HSM contains predictive methods for infrastructure improvement project alternative analysis and development/design including the use of national safety performance functions developed to predict crashes by severity specific facility types and base conditions; and associated crash modification factors (CMFs) to estimate the potential effects of design alternatives or changes from base conditions.
In 2017 the Kentucky Transportation Center developed a tool using the free and open-source statistical computing and graphics environment “R”. Utilizing methods outlined by the HSM, code was created in R to automate SPF development to improve regression models. The tool became known as SPF-R and allowed states that have not adopted newer methodologies due to the difficulties related to SPF development the ability to create Safety Performance Functions. SPF-R provides immediate feedback in SPF development, including goodness-of-fit measures and depictions of the model. SPF-R is now in the FHWA Safety Toolbox, but it does require someone with a working knowledge of how to run R code, as well as an application downloaded to a computer in order to run.
Recognizing that running code may be a barrier for some, this new version of the code takes the SPF-R and runs it on a server. A new web interface has been developed so SPFs may be developed through a user’s web browser simply by uploading a CSV file with certain predefined parameters. Users of this new tool will have fewer technical challenges getting SPF-R working as the mechanics are all handled online. SPF-R online is still free and open-source, but in this current form it is more accessible than ever before.
Tool Type:
Software
Data and System Requirements:
SPF-R User’s Guide: This application guide provides background information and serves as a how-to manual for SPF-R.
Owner Source:
university
Sponsor/Owner:
- Kentucky Transportation Center, University of Kentucky
Published:
Availability:
This software is free of charge at the following link:
Disclaimer:
This information is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained herein. This information does not constitute a standard, specification, or regulation. The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturer's names appear in this information only because they are considered essential to the objective of this publication.
Any opinions, findings, and conclusions or recommendations, and translations thereof, expressed in this publication are those of the author(s) and do not necessarily reflect the views of the Federal Highway Administration.