Accident and speed analysis evidence base 7 march 2013
This presentation is the property of its rightful owner.
Sponsored Links
1 / 34

A9 Safety Group PowerPoint PPT Presentation


  • 48 Views
  • Uploaded on
  • Presentation posted in: General

Accident and Speed Analysis - Evidence Base 7 March 2013. A9 Safety Group. Presentation Purpose. To provide a summary of the accident analysis and review of vehicle speeds and speed enforcement on the route

Download Presentation

A9 Safety Group

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Accident and speed analysis evidence base 7 march 2013

Accident and Speed Analysis - Evidence Base

7 March 2013

A9 Safety Group


Presentation purpose

Presentation Purpose

  • To provide a summary of the accident analysis and review of vehicle speeds and speed enforcement on the route

  • All supporting reports and analysis to be circulated in due course to group members for more detailed consideration


Presentation contents

Presentation Contents

  • Route Overview

  • Accident Analysis

  • Speed Analysis

  • Current Speed Enforcement

  • Next Steps / Further Considerations


Route overview

Route Overview

  • Route serving a mix of local and strategic traffic movements, connecting major conurbations and serving smaller towns

  • Critical link between the Central Belt and the North

  • Mix of dual with at grade junctions, single, WS2+1 and dual route provisions


Route overview traffic volumes

Route Overview – Traffic Volumes

  • Indicative Annual Average Daily Traffic Flows (2012)


Route overview traffic volumes1

Route Overview – Traffic Volumes

  • Noticeable seasonal variation in traffic flows on the route (example at Dunkeld below)


Accident analysis approach

Accident Analysis Approach

  • Route split into three distinct parts

  • STATS19 analysis (2007 to 2011)

  • Comparisons made against wider trunk road averages

  • Consideration made to standard STATS19 indicators (vehicle type, manoeuvre, weather / lighting conditions, road surface, driver age, driver postcode, time of day etc)

  • Route wide approach to identify key themes

  • More detailed review of police report for all fatal accidents

  • Targeted analysis by section (acc rate and KSI rate)

  • Identification of cluster locations to capture localised issues


A9 dunblane to perth summary statistics

A9 Dunblane to Perth – Summary Statistics

  • Accident Rate comparable with trunk road national average

  • KSI Ratio marginally higher than trunk road national average (0.26 v 0.24)

  • Annual accident levels declining


A9 dunblane to perth key safety themes

A9 Dunblane to Perth – Key Safety Themes

  • Higher number of HGV>7.5Ts involved in accidents (17% v 9% NE unit average)

  • 53% of right turn accidents are KSIs (compared to 29% NE unit average)


A9 dunblane to perth fatal accident analysis

A9 Dunblane to Perth – Fatal Accident Analysis

  • 4 out of 8 fatal accidents occurred at a junction

  • 3 out of 8 fatal accidents involved HGVs (1 accident with HGV>7.5T)

  • Only 1 of the fatal accidents was a single vehicle accident


A9 dunblane to perth section analysis

A9 Dunblane to Perth–Section Analysis

  • Two section accident rates are higher than the national average (7.7pia/100mvk)

    • Dunblane to Greenloaning (8.8pia/100mvk)

      • Influence of accidents in 2007

    • Blackford to Shinafoot (11.8pia/100mvk)

      • Over 50% of accidents were ‘single vehicle’ (35% on wider route and NE unit)

      • 56% of accidents involved roadside strikes (31% route average, 35% NE unit average) and the majority occurred in the Gleneagles area

      • Proposal under consideration as part of on-going SRS work to improve roadside safety


A9 dunblane to perth cluster identification

A9 Dunblane to Perth – Cluster Identification

  • 14 cluster sites identified with concentration of accidents

  • 10 of these sites have previously been identified / investigated / treated

  • Remaining 4 cluster sites be programmed for investigation and analysis for common causations

    • Auchterarder Bypass

    • Balhaldie Services

    • Crieff Road

    • Inveralmond Roundabout


A9 inverness tore to scrabster summary statistics

A9 Inverness (Tore) to Scrabster – Summary Statistics

  • Accident rate is higher than the trunk road national average (24.3 v 18.7 pia/100mvk)

  • But lower accident frequency due to lower traffic volumes

  • KSI Ratio is less than the trunk road national average (0.20 v 0.24)

  • Annual accident levels declining


A9 inverness tore to scrabster key safety themes

A9 Inverness (Tore) to Scrabster – Key Safety Themes

  • ‘Turning right’ the most common vehicle manoeuvre in accidents (13.5% compared to 6.1% NW unit average)

  • ‘Failed to look properly’, ‘failed to judge other persons speed’, ‘careless/reckless’ and ‘poor turn’ the most common contributory factor in accidents

  • 43% of accidents occurred at a junction (compared to 26% NW unit average)


A9 inverness tore to scrabster fatal accident analysis

A9 Inverness (Tore) to Scrabster – Fatal Accident Analysis

  • 9 fatal accidents (3 south and 6 north of Dornoch Bridge)

  • 50% of fatals north of Dornoch Bridge were due to ‘loss of control’

  • 3 out of 5 fatals north of Dornoch Bridge were single vehicle


A9 inverness to scrabster cluster identification

A9 Inverness to Scrabster – Cluster Identification

  • 9 cluster sites identified

  • 6 sites addressed / being addressed through safety improvements

  • 1 investigation identified no treatable common factors

  • 2 sites currently under more detailed investigation

    • Drummond Junction

    • Dunrobin Castle Junction


A9 perth to inverness tore overview

A9 Perth to Inverness (Tore) - Overview

  • Varying route provision requires analysis by route type

  • Single carriageway makes up 65% of the route length

  • 68% all accidents occurred on single carriageways

  • 77% of all KSI accidents occurred on single carriageways

  • Single carriageway KSI ratio (0.32) > trunk road national av. (0.24)


A9 perth to inverness tore key themes

A9 Perth to Inverness (Tore) – Key Themes

  • HGV>7.5Ts involved in 12.4% of accidents (compared to the NW unit average of 6.1%)

  • HGV>7.5T involved in 22.8% of accidents on single carriageways

  • Goods vehicles<7.5T involved in 13.6% of accidents on single carriageways (compared to NW unit average of 7.0%)


A9 perth to inverness tore key themes1

A9 Perth to Inverness (Tore) – Key Themes

  • Similar contributory factors are higher than the NW unit average on single and dual route types

  • However ‘fatigue’ more prevalent on single carriageway sections (4.1% compared to 0.8% on dual and 1.6% NW unit average)

  • And ‘sudden braking’ more prevalent on dual carriageway sections (6.0% compared to 3.9% on single and 4.0% NW unit average)


A9 perth to inverness tore fatal accident analysis

A9 Perth to Inverness (Tore) – Fatal Accident Analysis

  • 25 out of 31 fatal accidents occurred on single carriageways

  • HGVs>7.5T involved in 23% of fatal accidents


A9 perth to inverness tore fatal accident analysis1

A9 Perth to Inverness (Tore) – Fatal Accident Analysis

  • ‘Overtaking’, ‘moved out of lane’ and ‘loss of control’ the most common causes of fatal accidents

  • Only 1 overtaking accident involved an HGV>7.5T


A9 perth to inverness tore section analysis

A9 Perth to Inverness (Tore) – Section Analysis

  • 3 out of 25 route sections were identified to have an accident rate higher than the national average

    • Bankfoot (9.4 pia/100mvk)

    • Faskally (50.9 pia/100mvk)

    • Meall Mor to Kessock Bridge (9.0 pia/100mvk)

  • Road improvements delivered in 2009/2010 at Bankfoot and Faskally and in 2012/2013 across the Meall Mor to Kessock Bridge section


A9 perth to inverness cluster identification

A9 Perth to Inverness – Cluster Identification

  • 9 cluster sites identified

  • 6 sites addressed / being addressed through safety improvements

  • 1 site investigated but no works taken forward (Munclochy Junction)

  • 1 site investigated but no treatable common factors identified

  • 1 site currently under more detailed investigation

    • Granish (A95) Junction


A9 summary of vehicle speeds approach

A9 Summary of Vehicle Speeds - Approach

  • Speed data by vehicle class collected at 10 SRTBd counter locations across the route

  • Summary of data from full neutral months in 2012

  • Data summarised by speed bins, by hour, max speed to be used to inform existing speed enforcement regime


A9 vehicle speed summary average speeds

A9 Vehicle Speed Summary – Average Speeds

  • Evidence of vehicles travelling above the posted speed limit at every counter location interrogated

  • Most pronounced for HGVs>7.5Ts

* Approximate value


A9 current speed enforcement 2012

A9 Current Speed Enforcement (2012)

  • Speed Enforcement by Northern, Tayside and Central Police and Safety Camera Partnerships (SCPs)

  • Police enforcement through patrols on the route

  • SCP enforcement through 5 Fixed Safety Cameras

    • Dunblane to Perth (3)

    • Perth to Inverness (2)

  • And widespread mobile enforcement (109 sites) across the entire route


A9 current safety camera deployment

A9 Current Safety Camera Deployment

  • Fixed cameras had an average of 0.1 offences per hour in 2012

  • SCPs deployed mobile enforcement on the A9 for a total of approximately 1,500 hours in 2012


A9 post code analysis offenders

A9 Post Code Analysis – Offenders


A9 existing speed enforcement regime

A9 Existing Speed Enforcement Regime

  • Speed enforcement undertaken through a collection of fixed sites, mobile sites and police patrols

  • Higher offence rates recorded south of Inverness

  • Offenders typically reside across Scotland's key areas of population


A9 evidence base summary

A9 Evidence Base Summary

  • Accident Analysis

  • Dunblane to Perth

  • High severity of accidents at junctions

  • High number of single vehicle, roadside strike accidents in the Gleneagles area

  • Inverness to Scrabster

  • High number of accidents at junctions

  • High proportion of fatal accidents north of Dornoch Bridge single vehicle and due to loss of control


A9 evidence base summary1

A9 Evidence Base Summary

  • Perth to Inverness

  • High number of HGV>7.5Ts in accidents, particularly on single carriageways

  • Fatigue contributing to accidents is more common on single carriageway sections

  • Sudden braking contributing to accidents is more common on dual carriageway sections

  • Vast majority of fatal accidents occurred on single carriageways

  • Overtaking, moved out of lane and loss of control most common manoeuvres in fatal accidents


A9 evidence base summary2

A9 Evidence Base Summary

  • Vehicle Speeds

  • Evidence of a significant proportion of vehicles exceeding the posted speed limit

  • Speed Enforcement

  • Highest offence rates recorded south of Inverness


Next steps

Next Steps……

  • Discuss key outcomes

  • Reach outline consensus on issues

  • Circulate supporting reports

  • Identify appropriate measures


Accident and speed analysis evidence base 7 march 20131

Accident and Speed Analysis - Evidence Base

7 March 2013

A9 Safety Group


  • Login