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.



Millions for research into maritime transport and the environment

Maritime transport is a major source of emissions of harmful air pollutants and carbon dioxide. In a new project, a research team from the Swedish National Road and Transport Research Institute (VTI) and the University of Gothenburg has received SEK 6.4...


New research programme for more efficient travel

The Swedish National Road and Transport Research Institute (VTI) is playing an important role in a major new research programme to find radical solutions leading to fewer trips and more efficient travel, along with tools to enable better use of roads and...


Simulator used to practice emergency responses safely

Emergency responses of the police, ambulance, and rescue services are associated with a high risk of accidents, but practicing them in real traffic is neither safe nor permissible. A simulator-based method developed by the Swedish National Road and Transport...


Simulation of cut-in by manually driven vehicles in platooning scenarios

A study in a VTI-driving simulator has showed that a platoon will be able to handle a cut in from a manually driven car. The results of this study have recently been presented at two conferences in Japan.



The five-year anniversary of European Road Profile Users' Group (ERPUG) Forum will take place at Ramboll head quarter, Copenhagen, Denmark October 19-20, 2017.


Self-driving buses in Sweden next year?

A self-driving, fossil-free bus. This idea might become reality through a forthcoming collaborative project involving the Swedish National Road and Transport Research Institute (VTI), Linköping University and several other participants. The project group aim...