Identification of Hazardous Road Why is Hazardous Road Location - - PDF document

SLIDE 1 Niels Agerholm, Traffic Research Group, Aalborg University

• No. 1 of 20

ICTCT workshop 2015

Identification of Hazardous Road Locations on the basis of Floating Car Data

Niels Agerholm Associate Professor Division of Transportation Engineering

• Dept. of Civil Engineering

Aalborg University Niels Agerholm, Traffic Research Group, Aalborg University

• No. 2 of 20

ICTCT workshop 2015

Agenda

• Why is Hazardous Road Location treatment necessary?
• A need for new methods?
• The Method briefly
• Scientific background
• Data source
• Results and status

Niels Agerholm, Traffic Research Group, Aalborg University

• No. 3 of 20

ICTCT workshop 2015

A definition

• Hazardous Road Location (HRL) is also known as Black Spot
• HRL:

A location which is more accident-prone than it it should be expected due to traffic level, road furniture and road design.

• 33% reduction in injury accidents!

The Handbook of Road Safety Measures - Second Edition (2009) Niels Agerholm, Traffic Research Group, Aalborg University

• No. 4 of 20

ICTCT workshop 2015

A need for new methods?

• How comprehensive are the official

traffic accident databases?

• Large variation from country to

country

• Depends significant of the involved

road users

• Significant dark figure

Reporting rate (%)

Car

• ccupant

s Motor cycle riders Cyclists Australia 73 53 7 Denmark 48 31 10 France 63 45 11 Germany 52 44 22 Great Britain 68 44 66 The Netherlands 63 56 24 Norway 56 37 16 Sweden 77 67 29 USA 65

• 26

(Old results in general)!!!

The Handbook of Road Safety Measures - Second Edition (2009) Niels Agerholm, Traffic Research Group, Aalborg University

• No. 5 of 20

ICTCT workshop 2015

A need for new methods?

• An exceptional Danish challenge
• Small-scale studies underpin this

Accident reporting: Denmark

1998 2007 2011

• No. of injured

Police 9,660 6,897 4,158 Police & Hospital 46,075 47,792 41,272 Police-reported share 21% 14% 10%

Statistics Denmark 2015 Niels Agerholm, Traffic Research Group, Aalborg University

• No. 6 of 20

ICTCT workshop 2015

A need for new methods?

Small-scale Danish studies underpin the need for a new/ additional method

• Only 10-12% injury accident were

reported

• Especially accidents with young

people have high black figures

• Only 5 of 15 HRL intersection

were found from both Police and Hospital data

• Occasionally erroneous treatment

in HRLs due to low share of reported accidents

(Andersen & Sørensen 2004; Jørgensen & Bach 2007; Bunton & Celis 2009)

SLIDE 2 Niels Agerholm, Traffic Research Group, Aalborg University

• No. 7 of 20

ICTCT workshop 2015

Hypothesis

It is the hypothesis that concentration of registered hard decelerations on locations indicates a potential HRL

Niels Agerholm, Traffic Research Group, Aalborg University

• No. 8 of 20

ICTCT workshop 2015

The Method briefly

• In principle it is an area-based conflict

study technique

• Based on Floating Car Data (FCD)
• The idea is that HRLs induce more abrupt

decelerations than else (jerks)

• Too many in one location indicates a HRL
• Small scale studies indicate that the jerk

gives a more clear pattern (the derived of the deceleration)

• A Forward-looking approach (don’t wait

until the accidents appear)

• Vision Zero !!

Accidents Serious Jerks Moderate Jerks Normal driving Fatal accidents Injury accidents Inspired by Svensson & Hydén 2006 Niels Agerholm, Traffic Research Group, Aalborg University

• No. 9 of 20

ICTCT workshop 2015

Conflict indicator?

• Avoidance can be made in three ways:
• Decelerate
• Accelerate
• Sideways
• Decelerations (and jerks) are selected:
• Intuitively
• Support from literature: 72-98% of all accident avoidance activities

(Horst 1984, Hydén 1987, Hantula 1994, Nygård 1999)

Niels Agerholm, Traffic Research Group, Aalborg University

• No. 10 of 20

ICTCT workshop 2015

Speed, Decelerations, and Jerks – connection

Niels Agerholm, Traffic Research Group, Aalborg University

• No. 11 of 20

ICTCT workshop 2015

Scientific background

• Nygård (1999):
• Found that serious conflicts resulted in jerks that differed significant from jerks in case of voluntary

braking

• Found that jerks gave more clear results than decelerations
• Svendsen et al. (2008)
• Supported Nygård’s jerk-based approach
• Used low frequency data (1 Hz)
• Agerholm & Lahrmann (2012)
• Speed changes are very sensitive to bad GPS connections
• Low speed: deceleration and jerks were unreliable
• Jerks – and partly decelerations are highly affected by uneven surfaces (Speed bumps, pot

holes, bad managed road surface etc.)

Niels Agerholm, Traffic Research Group, Aalborg University

• No. 12 of 20

ICTCT workshop 2015

Data from ITS Platform

• Floating Car Data: GPS data from

vehicles carrying out their ‘normal’ purpose on the road network

• ITS Platform:
• 10 Hz
• 380 cars
• Acceleration data included
• ~15 Billion records on accelerations
• ~14.5 million km
• ~1.4 million trips
• Simplification and selection is required

Accidents Serious Jerks Moderate Jerks Normal driving Fatal accidents Injury accidents

SLIDE 3 Niels Agerholm, Traffic Research Group, Aalborg University

• No. 13 of 20

ICTCT workshop 2015

From raw data to relevant data

Stepwise data treatment:

• Each car: 1,000 highest

decelerations and jerks in 3 months and similarly 1,000 jerks

• Anonymisation
• Selected area: Aalborg Municipality
• Removal of small

decelerations/jerks

• Removal of data on motorways

(high speed often make vibrations)

• Removal of low speeds (<20 km/h)
• Removal of data around speed

bumps

(~2,300 speed bump in North Jutland) Niels Agerholm, Traffic Research Group, Aalborg University

• No. 14 of 20

ICTCT workshop 2015

Study approaches

9 approaches in total

• 3 approaches with 3 sets of variations:
• Decelerations
• Negative jerks (jerks)
• Peak-2-peak jerks (p2p jerks)

Indicator variations:

• The limiting |size| of decelerations/jerks/p2p jerks
• Number of registrations

Niels Agerholm, Traffic Research Group, Aalborg University

• No. 15 of 20

ICTCT workshop 2015

What do the decelerations show?

Niels Agerholm, Traffic Research Group, Aalborg University

• No. 16 of 20

ICTCT workshop 2015

What do the jerks show?

Niels Agerholm, Traffic Research Group, Aalborg University

• No. 17 of 20

ICTCT workshop 2015

What do the p2p jerks show?

Niels Agerholm, Traffic Research Group, Aalborg University

• No. 18 of 20

ICTCT workshop 2015

Lessons learnt

• Data still require significant cleaning effort
• Decelerations can hardly be seen as a risk indicator
• Jerks seems to indicate some HRLs although uneven surface is a problem
• P2P jerk seems very sensible to pot holes, speed bumps and uneven road

surface in general

SLIDE 4 Niels Agerholm, Traffic Research Group, Aalborg University

• No. 19 of 20

ICTCT workshop 2015

Next steps

• Ensure ≥ 1,000 jerks (deceleration?) from all cars (~380)

where all data due to uneven surface are removed.

• Make density analyses
• Identify locations with high concentrations
• Search careful for any data errors affecting the reliability.
• Make inspection on the location (Street View and real

inspection)

• Compare 2 six-months periods
• Verify/falsify the hypothesis

Niels Agerholm, Traffic Research Group, Aalborg University

• No. 20 of 20

ICTCT workshop 2015

Thank You☺

Niels Agerholm Associate Professor Division of Transportation Engineering

• Dept. of Civil Engineering

Aalborg University +45 61 78 04 55 na@civil.aau.dk Robin Jensen M.Sc. in Eng. COWI Ltd Camilla Sloth Andersen Assistant Professor Division of Transportation Engineering

• Dept. of Civil Engineering

Aalborg University