Condition Surveys 2011/12 Results Andy Pickett Director Appia Infrastructure Solutions

Themes 1.Survey Strategy: what surveys should we be doing? 2.Survey Quality and Management: how do we ensure data quality, consistency and reliability? 3.Reporting and Utilisation: how do we make use of the surveys to maximise value to users?

BPRN Survey Strategy Objectives: Ensure best return on the investment in data and maximise use by boroughs Align with borough maintenance policy and practice, asset management plans and service level monitoring Ensure consistency and quality of data and reports Take advantage of survey developments nationally

BPRN Survey Strategy 100% DVI since % TTS/SCANNER since 2004/05 100% SCRIM since 2005/06

DVI Surveys Never intended as a network tool Limited capability for surveys of this size Third term contract since 1999 Only two contractors/sub-contactors Advantage rarely taken of survey capability SCI – ‘maintenance should be considered’ SCI sensitive to ‘cracking’ recording

SCANNER Road Condition Index ‘Plan maintenance soon’ Consistent annual trend output TRL Accredited Machines Good comparison with DVI SCI Accurate rut depth measurement –Should replace the DVI rut defect category

Which Network Survey? Driven CVI –no footway details Driven CVI plus FNS Walked CVI –expensive & lacks detail SCANNER –no footways DVI –expensive

DVI Survey Quality and Management Potential for SCI defects to be interpreted as non-SCI defects (and vice versa) –e.g. Transverse/Reflection Cracking Consequent potential for variation between surveyors and survey contractors Needs shared QMS values and procedures to ensure improved reliability

DVI Survey Quality and Management Audit Surveys of each inspector used at the start of the survey Joint inspections between project manager and each surveyor used to ensure correct interpretation of defects Production of supplementary guidance to the UKPMS Manual to ensure correct interpretation of defects

Survey Quality Recommendations Transverse Cracking Map locations of covered concrete from core/GPR information and issue to surveyors Wheel Track Cracking and Whole Carriageway Major Additional local guidance be issued describing the circumstances in which Wheel Track Cracking should be recorded, giving examples Wheel Track Rutting Rutting to be removed from the DVI specification and DRUT rutting extracted from SCANNER used as an alternative

Reporting of DVI Data Structural Condition Indicator Percentage of length with a SCI > 70 RED = % network length SCI > 70 AMBER = % network length SCI 30 to 70 GREEN = % network length SCI <30

SCI Indicator - Defects `Recorded AsNotes Whole Carriageway Major Cracking Area (m2) Wheel Track Major Cracking Lane Length (m) Since full XSP referencing is used the maximum length is the sub-section length Severe Local Settlement/Subsidence Area (m2) Wheel Track Rutting Depth (mm)

SCI Indicator – Defect Rating

Carriageway Defects NOT Contributing to Indicator Defect Recorded As Notes Moderate Local Settlement/SubsidenceArea (m2)Difference in level between 13mm to 30mm Transverse/Reflection Cracking Severity 1NoTo be recorded on covered concrete Transverse/Reflection Cracking Severity 2NoTo be recorded on covered concrete Whole Carriageway Major Chip LossArea (m2) Only applies to surfaces with surface applied chippings (e.g. surface dressing, high-friction surfacing and micro-asphalt) Whole Carriageway Major FattingArea (m2) The appearance of bituminous binder on the surface course such that the friction material is flush or covered. Whole Carriageway Major FrettingArea (m2) Total loss of surface or, in the case of surfaces with surface applied chippings loss of material to depth greater than 20mm. Includes potholes. Whole Carriageway Minor Chip LossArea (m2) Only applies to surfaces with surface applied chippings (e.g. surface dressing, high-friction surfacing and micro-asphalt) Whole Carriageway Minor CrackingArea (m2) Whole Carriageway Minor FattingArea (m2) An excess of bituminous binder on the surface course where the binder is NOT flush with or covering the friction material. Whole Carriageway Minor FrettingArea (m2)Partial loss of surface or, in the case of surfaces with surface applied chippings loss of material to a depth less than 20mm.

SCI Calculation (Highest of rated values) 1 * Whole Carriageway Major Cracking 1 * Severe Local Settlement/Subsidence 1.4 * Wheel Track Major Cracking 1 * Wheel Track Major Cracking * Wheel Track Rutting 0.5 * Wheel Track Major Cracking + 1 * Wheel Track Rutting

SCI-based DVI – Issues Relatively small number of defects used Particularly sensitive to recording or mis-recording of cracking Many other defects recorded that are important to serviceability and as a indicator of maintenance need are collected but not reported (Fretting/Potholing, Surface Defects, Footway Defects) Does not align with current maintenance practice with relatively few strengthening/reconstruction treatments on BPRN

COMPARISONS SCANNER RCI trends to 2011/12 good DVI SCI trends to 2010/11 good SCANNER RCI v DVI SCI 2010/11 good 2011/12 DVI SCI – new survey company –Trend with previous DVI data not good –Comparison with SCANNER RCI not good Appia asked to audit and to present results

SCANNER RCI 2010/11 and 2011/12 map Good trend/comparison

DVI SCI 2010/11 and 2011/12 map Concern over trends

DVI SCI and SCANNER RCI 2010/11 map Good Comparison

DVI SCI and SCANNER RCI 2011/12 map Comparison not good

“Red” Values (SCI>70)

2011/12 DVI Data Issues Generally higher PIs reported, largely attributable to differences in interpretation and recording of cracking between survey contractors More marked in some boroughs than others

ISSUES Confidence in the DVI results Looked at trend information Both SCANNER year on year DVI year on year DVI/SCANNER over the last two years Results presented for all boroughs (Provisional for DVI )

Options Rely on 2010/11 DVI survey data until we can accept the 2011/12 Appia to investigate DVI results and assist with review Do we need an alternative DVI indicator? SCI used but little reconstruction Wearing Course indicator might be better Rely on SCANNER as the network tool? –Only use DVI as a investigatory tool for areas highlighted in SCANNER

Recommendations - Reporting Development of a alternative/supplementary indicator(s) –consider the wider range of DVI defects such as fretting (including pot-holing) and surface defects which impact upon the serviceability of the network but which are not currently reported –align with maintenance practitioners’ requirements –Simpler, more transparent Supply and processing of sample data early in the process to identify and correct issues with data quality, format and integrity Review and update survey regime

Next Steps Release DVI HMDIF data to Boroughs Discuss recommendations with HMSG Agree new survey regime Agree new reports and indicators New indicator can be applied to the 2011/12 data and be repeated with the 2013/14 surveys Implement survey recommendations for 2013/14 Surveys