How to preserve and improve safety with tight maintenance budgets Fergus Tate National Manager Traffic and Safety November 2012 1 Introduction Background Objectives A method for assessing the value of safety features The role of delineation devices Understanding Research Context Study types 2 Burdett and Nicholson 3 Elvik et al 4 Kloeden 400 350 Relative Risk 300 250 200 150 100 50 0 -10 -5 0 5 10 15 20 25 30 Deviation from Mean Speed (km/h) 5 Sources •Federal Highways Administration Crash Modification Factor Clearinghouse (FHWA 2012) •Austroad Road Safety Engineering Toolkit (Austroads, 2012a) •Effectiveness of Road Safety Engineering Treatments, (Austroads, 2012b), •The Handbook of Road Safety Measures (Elvik et al, 2009) •TERNZ Delineation Benefit Calculator 6 Device and context Post Mounted delineators in general Particularly on vertical and horizontal curves Edgelines on curves Edgelines on straights Edgelines on curves and straights Centrelines Crash reduction1 -4% 7% Elvik et al 25% FHWA4 30% Austroads 26% to 33% 6% 3% at higher crash locations Edgelines centreline and post mounted delineators FHWA FHWA Elvik et al and FHWA2 8% FHWA 30% Austroads 1% Elvik et al and FHWA3 33% FHWA4 30% to 35% Edgeline and centreline markings Source2 Elvik et al and FHWA3 Austroads 24% Elvik et al and FHWA3 14% FHWA Elvik et FHWA3 45% al and 7 Research Context What sort of study • Before and after • Cross sectional What context • Measures • Road type 8 Key Crash Types Other 11% Run off road 51% HeadOn 25% Intersection 13% 9 Burdett and Nicholson 10 Delineation & Markings Edgelines Edge and Centreline EMPs Basic Tools -Hierarchy Marker Post Edge Lines Provide information about alignment ahead Mark the edge of the carriageway Define curves Centre Lines Add to curve definition Keeps vehicle to the left Chevrons Provide high level positive guidance Advanced Tools Wide lines Less subject to degradation and wear additional day and night time guidance Increases reflected light Brighter markings RRPMs Good night and wet weather delineation ATP Increased reflectivity and fatigue assistance Pictures of access on curve ATP SH1 Treated Adjacent SH30 Standard Markings 4000 400 3500 350 3000 300 2500 250 2000 200 1500 150 1000 100 500 50 0 0 0 250 500 750 1000 1250 Annual Average Daily Traffic (AADT) 1500 Cumulative Reported Crashes Per Year Cumlative Kilometres of Highway Run-off-road & Head-on Crashes Length of Highway Reported Fatal + Serious Injury Crashes Reported Injury Crashes 19 Combined Treatments Post mounted delineators (on curves) Edgelines on curves Centrelines 25% 30% (range 26% to 33%) 33% 20 Combined Treatments Post mounted delineators (on curves) Edgelines on curves Centrelines Total 25% 30% (range 26% to 33%) 33% 88% 21 Combined Treatments Post mounted delineators (on curves) Edgelines on curves Centrelines Total CRFt Where CRFt CRFn So CRFt 25% 30% (range 26% to 33%) 33% 88% = 1- (1-CRF1)(1-CRF2)(1-CRF3)......(1- CRFn) = total crash reduction = individual crash reductions = 1- (1-0.33)(1-0.30)(1-0.25) = 0.65 22 Combined Treatments Post mounted delineators (on curves) Edgelines on curves Centrelines Total CRFt Where CRFt CRFn So CRFt 25% 30% (range 26% to 33%) 33% 88% = 1- (1-CRF1)(1-CRF2)(1-CRF3)......(1- CRFn) = total crash reduction = individual crash reductions = 1- (1-0.33)(1-0.30)(1-0.25) = 0.65 Then take 2/3 0.65 x 0.67=0.43 23 Establishing the Benefits AADT 250 500 750 1000 1250 1500 Run-Off-Road and Additional Crashes per year as a result of Head-On Crashes/yr removing the following delineation devices Centreline Edgeline Marker All three With AADT All Injury Posts less than Only Only (Fatal + Serious) Cumulative length 58 0.7 0.3 0.2 0.3 0.6 376 (0.3) 16.7 (0.1) 7.2 (0.1) 5.6 (0.1) 7.2 (0.2) 13.7 1536 (7.0) 30.0 (3.0) 12.9 (2.3) 10.0 (3.0) 12.9 (5.7) 24.5 2587 (13.0) 64.0 (5.6) 27.4 (4.3) 21.3 (5.6) 27.4 (10.6) 52.4 2343 (23.0) 173.3 (9.9) 74.3 (7.7) 57.8 (9.9) 74.3 (18.8) 141.8 3938 (56.0) 241.3 (24.0) 103.4 (18.7) 80.4 (24.0) 103.4 (45.8) 197.4 (76.7) (32.9) (25.6) (32.9) 24 (62.8) Summary • Understand the role or function of the devices • Ensure a range of research is consulted • Understand, the research type, quality and context • Not focus on individual sections of highway 25