From Black Spots to Grey Road Sections - What is the Right Way?

1
From Black Spots to Grey Road Sections- What
is the Right Way?

• Michael Sørensen
• Research Engineer, PhD
• Institute of Transport Economics

2
Background for presentation
PhD project Hazardous road sections in rural
areas EU project Black Spot Management and
Network Safety Management (RIPCORD)
3
Background for project
BSM Long tradition and is now considered as
ineffective NSM Supplement to BSM in the last
5-10 years (Identification, analysis and
treatment of hazardous (grey) road sections)
1) What do we mean with NSM and RSI? 2) Where do
NSM and RSI differ and overlap? 3) Do we need
both NSM and RSI?
RSI Supplement to BSM and RSA in the last 5-10
years RSA Adopted in more and more countries
4
Objective, focus and method

• Objective
• Clarify the basis philosophy for NSM
• Evaluate how NSM differ from BSM and RSI
• Evaluate if NSM is needed or if focus should be
  on RSI
• Focus
• NSM in Denmark (main roads in rural areas)
• Method
• Literature survey of exiting method and
  scientific articles
• Interview with 18 Danish key persons
• Development of a Danish method for NSM
• Analysis of treatment suggestions for 9 grey road
  sections

5
A new Danish method for NSM - Category and
severity based identification
Definition Uniform road sections (2-10 km),
where RPI gt 4 (Largest potential for saving
the most serious accidents)
RPI RWACD AWARD gt 4
RPI RWACD AWACD 4 Reduction potential index Recorded accident cost weighted accident density Average accident cost weighted accident density Estimered identification criterion for Denmark

ACD W Accident density for accidents with different severity Weight for accidents with different severity
6
Weights Accident costs AC ser (CPkilled
xkilled) (CPser xser) (CPmin xmin)
CPracc ACmin (ACmin xmin) CPracc ACprop
CPracc Costs related to people and property
damage CPkilled 10,404,000 Dkk CPser
1,085,000 Dkk CPmin 295,000 Dkk CPracc
100,000 Dkk Number of injured road
users xKilled Killed per accident xser Serious
injured per accident xmin Minor injured per
accident
7
Identification - an example

• Ringkøbing County and Viborg County
• 1.561 km
• 290 sections
• Average length 5,4 km
• 18 grey road section
• Grey road sections comprise 4-8 of the road
  network

Ringkøbing County
8
Different identification methods
Reference to population of site Section length Reference to normal safety level Recorded or expected number Accident severity considered Accident period
Denmark Yes 2-10 km Yes, Category analysis Recorded Yes, Weights for 4 different categories of accident 5 years
Germany Yes 3-10 km Yes, Category analysis Recorded Yes, Weights for 3 different categories of accident 3 years
Norway Yes 1 km (more) Yes, Accident prediction models Expected Yes, Weights for 4 different categories of injured 8 years
USA Yes Several miles Yes, Accident prediction models Expected Yes, Possible to select the most severe accident Optionally
9
NSM compared with RSA, RSI, and BSM
Philo-sophy Identifi-cation Analysis Severity Length Frequ-ency When
RSA Proactive New roads Not accident based - All new roads Once 0-1 year after opening
RSI Proactive Not accident based Not accident based - 2-10 km Every 2-4 year Over 3-4 years after opening
NSM Pro- and reactive Accident based Accident based and general problems Included 2-10 km Every 2-4 year Over 5 years after opening
BSM Reactive Accident based Only accident based Not included Under 0.5 km Every 1-2 year Over 5 years after opening
10
Assessment of method and philosophy

• An systematic evaluation of 108 measures proposed
  on 9 grey road sections
• 71 are only proactive (relate only to problems
  identified in the road inspection)
• Only 29 of the measures have both a reactive
  and proactive nature (relate both to problems
  identified in the accident analysis and in the
  road inspection)

Road section A B C D E F G H I Total
Remedial and preventive 7 3 1 3 3 5 2 3 4 31
Only preventive 9 11 7 13 5 9 6 5 12 77
The nature of measures proposed on 9 grey road
sections
11
Conclusion NSM is not the way

• The category and severity based method for
  identification is better than the options, which
  the Danish road authorities have at the present
  moment
• However, it is difficult to identify
  site-specific local accident and injury factors
  on the grey road sections
• The analysis gets the nature of being a general
  road inspection (RSI) with attention on standard
  improvements
• Discrepancy between philosophy and actual work
  accident based identification and not accident
  based analysis and treatment
• Road inspections and standard improvements
  contribute to traffic safety improvements, but
  the ranking may be done in a better way by an not
  accident based method (RSI)

12
From Black Spots to Grey Road Sections- What
is the Right Way?

• Questions and comments