A comparative study of the application of the standard kernel density estimation and network kernel density estimation in crash hotspot identification

Yue Tang
Michael A Knodler
Mi-Hyun Park

Despite a growing number of studies have claimed the network Kernel Density Estimation (network KDE) a more advanced method for crash hotspot identification than the planar Kernel Density Estimation (planar KDE), few conducted comprehensive study to examine their accuracy and practicality on a large-scale basis (i.e. municipal and county). This research attempted to fill the gap by conducting a comparative study of planar KDE and network KDE using the crash data of Hampden County, Massachusetts from 2009 to 2011. A two-tier planar KDE and a network KDE were implemented using the Kernel Density tool in ESRI ArcGIS 10 and SANET 4.1 developed at University of Tokyo respectively. Results showed that (1) Planar KDE is computationally inexpensive and easily accessed. (2) Both methods yielded virtually similar hotspot patterns but with different rankings of the high crash locations. (3) In identifying specific hotspot locations, network KDE could achieve more accurate results and was more timesaving, although multiple runs of planar KDE identified specific locations as well. Accordingly, several suggestions were made for crash hotspot analysis: (1) Since KDE takes the interrelationship among crashes into consideration, it is a more statistically sound approach than traditional methods in crash hotspot identification and can be widely adopted by state and local agencies for initiating safety improvement projects. (2) Planar KDE is recommended to identify general hotspot patterns on large-scale basis for its practicality and efficiency. (3) Network KDE is recommended to identify specific intersections and roadway segments for accuracy.



Cost Benefit Analysis (CBA) workshop in Stockholm

An open seminar and workshop in Stockholm will be held on 25-26 April 2018. The workshop deals with the use of CBA as a basis for decision-making in the public sector. The workshop is organized by, among others, Professor Jan-Eric Nilsson, VTI.



Ulf Sandberg has been presented with the TTI Lifetime Achievement Award 2018

VTI’s Senior Research Leader Ulf Sandberg has been presented with the TTI Lifetime Achievement Award 2018 for his work on research into tyres and road surface.


Steps need to be taken to increase traffic safety of automated cars

Several steps are necessary to ensure that automated and connected cars will lead to increased traffic safety – everything from ensuring that technology takes vulnerable road users into account, to new forms of driver training. This has emerged in a position...


FALCON examines challenges in the transport sector

VTI is one of several important partners in the major FALCON project*, whose purpose is to create knowledge and insight regarding the transport sector. In an initial subproject, VTI has produced a manual on transport, logistics and multimodality.


VTI joined research cooperation in China

In December 2017 VTI became a member of China-Sweden Research Centre for Traffic Safety (CTS).


Swedish German research collaboration on Electric Road Systems

The project “Swedish-German research collaboration on Electric Road Systems” (CollERS) has now officially started. The goal of the project is to increase the common knowledge around Electric Road Systems by cooperation between Germany and Sweden and to...


Electric Road Systems Conference 2018

After a successful first conference in June 2017, the Swedish research and innovation platform for electric roads is arranging the second dedicated International Conference on Electric Road Systems (ERS) June 13th and 14th 2018.