DS/CSB/515

THE KNOWLEDGE Issue No 03 Issue Date July 09

Concrete Step Barrier Design Guidance Barriers and Roadside Noise Concrete Barriers and Roadside Noise

Test site on M25, north of Junction 18

Introduction Height above Positions In 2005, Britpave commissioned a study to investigate carriageway the impact on roadside noise arising from installation of A & B 1.2 m concrete barriers in the central reserve. Arup Acoustics conducted a field study and theoretical analysis to establish B & C 1.2 m any differences in roadside noise levels, comparing A’ & B’ 2.2 m concrete and steel central reserve barriers. The full results of the study are given in an Arup Acoustics report, available Table 1: Receiver positions from Britpave1. A and B were located 40 m either side of the steel/concrete barrier interface to avoid the influence of noise from the Empirical Study adjacent segment. An empirical study was carried out on the southbound carriageway of the M25 near Junction 18, where the central Noise measurements were taken over a period of ten reserve safety barrier changes from concrete to steel. The minutes; each test was repeated three times. test site was selected for: Measurements at B and C, both opposite steel central • Steady flow; reserve barrier, were used as a control test to determine • Even gradient; the variation in noise levels at two positions with the same • No significant reflective surfaces adjacent to the road; barrier type. • Consistent conditions.

Noise level readings were taken at three positions A, B and C, see Figure 1 (overleaf). Readings at A and B were taken at two receiver heights, with A’ and B’ located 1 m above A and B respectively. 1 Barrier Acoustics Study: The acoustics effects of concrete central reserve safety barriers. Britpave. 2006

Measurements were taken at two positions simultaneously ² ISO 9613 Acoustics - Attenuation of sound during propagation outdoors as given in Table 1.

CONCRETE STEP BARRIER Design Guidance DS/CSB/515 Concrete Barriers and Roadside Noise Prepared for Britpave by Arup E-mail [email protected] Facsimile 01276 33160 Website www.britpave.org.uk Concrete Barriers and Roadside Noise DS/CSB/515 Britpave Riverside House, 4 Meadows Business Park, Station Approach, Blackwater, Camberley, Surry GU17 9AB Prepared for Britpaveby Arup CONCRETE STEPBARRIERDesign Guidance difference intrafficnoiselevelsatagreater receiver height. Results ofthetestatlocationsA’&B’shownosignificant roadside noiselevelsatthesereceiver positions. show thatthebarriertypehasanegligibleeffecton very similar(Table 2) andhighlyrepeatable. Theresults The results ofthetestsatlocationsA&BandCare Results ofEmpiricalStudy heights tobeconsidered. empirical results andallowed different barrierandreceiver A theoretical analysiswasalsocarriedouttovalidatethe Theoretical Study Figure 1:Layout ofnoisereceiver positions(NottoScale) Table 2:Results from empiricalfieldstudy Measurement Har Test Number Test Number Test Number Figure 1 Variation Variation Variation d 1 2 3 4 5 7 6 8 9 Concr ete safetybarrier Location Location Location 89.6 89.8 89.6 90.0 89.6 88.6 89.6 88.4 88.2 0.4 0.2 0.4 A’ A B (L Noise Level A10, 10min A’ AB Location Location Location ) dB 90.0 89.6 89.8 90.2 90.0 88.4 89.8 88.4 88.0 0.4 0.4 0.4 5m B’ B C 40m Difference (A’ -B’) (B -C) (A -B) -0.4 -0.2 -0.2 -0.4 -0.2 0.2 0.2 0.0 0.2 Steel safetybarrier 40m Table 3:Results from theoretical analysis the road surface. height of0.15mandtopbarrier0.5above and 1.0m.Thesteelbarrierwasmodelledwithaguard rail The modelwasrunwithconcrete barrierheightsof0.6m screening from theoppositecarriageway. representing locationsthatreceive progressively less obtained withreceptors atheightsof1m,2mand4 locations tothoseusedforthefieldsurveyandresults Noise receptors inthemodelwere positionedatequivalent level torepresent trafficnoise. both sidesofthecentralreserve, 0.5mabovecarriageway The modelusedseparatenoise-linesources foreachlane, ISO 9613 concrete andsteelcentralreserve safetybarrier, usingthe A computernoisemodelofthemotorwaywascreated with comparing concrete and steelcentralreserve barriers. that there isanegligibledifference in roadside noiselevels The results from theempiricalandtheoretical studies, show Summary across arangeofreceiver heights. between thesteelandconcrete centralreserve barriers, This showsanegligibledifference inpredicted noiselevels Results from thetheoretical analysisare showninTable 3. Results ofTheorectical Study Receiver Receiver surface surface height above road (m) 4 2 1 ² environmental noiseprediction method. DS/CSB/515 B’ Difference innoiselevelsbetweenthe barrier 5 mfromroad 0.6 m - 0.1 - 0.1 0.0 Concrete andSteelbarriers edge Concrete BarriersandRoadside Noise (concrete -steel)(dB) 80m Har Southbound carriagewa Nor barrier 1.0 m - 0.5 - 0.1 0.0 d shoulder thbound carriageway barrier 0.6 m - 0.1 - 0.1 - 0.4 10 mfromroad Issue DateJuly09 THE KNOWLEDGE edge y Issue No03 C barrier 1.0 m - 0.6 - 0.1 0.0