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Observations on the Relationship between Crash Frequency and Traffic Flow

Wagner, Peter and Hoffmann, Ragna and Leich, Andreas (2021) Observations on the Relationship between Crash Frequency and Traffic Flow. Safety, 7 (1), pp. 1-18. Multidisciplinary Digital Publishing Institute (MDPI). doi: 10.3390/safety7010003. ISSN 2313-576X.

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Official URL: https://www.mdpi.com/2313-576X/7/1/3/htm


This work analyzes the relationship between crash frequency $N$ (crashes per hour) and exposure $Q$ (cars per hour) on the macroscopic level of a whole city. As exposure, the traffic flow is used here. Therefore, it analyzes a large crash database of the city of Berlin, Germany, together with a novel traffic flow database. Both data display a strong weekly pattern, and, if taken together, show that the relationship N(Q) is not a linear one. When Q is small, N grows like a second-order polynomial, while at large Q there is a tendency towards saturation, leading to an S-shaped relationship. Although visible in all data from all crashes, the data for the severe crashes display a less prominent saturation. As a by-product, the analysis performed here also demonstrates that the crash frequencies follow a negative binomial distribution, where both parameters of the distribution depend on the hour of the week, and, presumably, on the traffic state in this hour. The work presented in this paper aims at giving the reader a better understanding on how crash rates depend on exposure.

Item URL in elib:https://elib.dlr.de/140249/
Document Type:Article
Title:Observations on the Relationship between Crash Frequency and Traffic Flow
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Wagner, PeterPeter.Wagner (at) dlr.dehttps://orcid.org/0000-0001-9097-8026
Hoffmann, RagnaRagna.Hoffmann (at) dlr.dehttps://orcid.org/0000-0002-6607-5406
Leich, Andreasandreas.leich (at) dlr.dehttps://orcid.org/0000-0001-5242-2051
Date:11 January 2021
Journal or Publication Title:Safety
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In ISI Web of Science:Yes
DOI :10.3390/safety7010003
Page Range:pp. 1-18
Publisher:Multidisciplinary Digital Publishing Institute (MDPI)
Keywords:road safety; traffic states; crash rates; temporal crash rate pattern
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Transport
HGF - Program Themes:Road Transport
DLR - Research area:Transport
DLR - Program:V ST Straßenverkehr
DLR - Research theme (Project):V - D.MoVe
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Transportation Systems > Evaluation of Transportation
Deposited By: Wagner, Dr. Peter
Deposited On:15 Jan 2021 10:56
Last Modified:15 Jan 2021 10:56

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