Concrete Barriers and Roadside Noise DS/CSB/515

DS/CSB/515 THE KNOWLEDGE Issue No 03 Issue Date July 09 Concrete Step Barrier Design Guidance Concrete Barriers and Roadside Noise Concrete Barriers and Roadside Noise Barriers and Roadside Concrete 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 road 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 traffic 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 road surface 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 THE KNOWLEDGE Issue No 03 Issue Date July 09 DS/CSB/515 Figure 1 Hard shoulder Northbound carriageway Steel safety barrier Concrete safety barrier Southbound carriageway Hard shoulder ABC 5m 40m 40m 80m A’ B’ Figure 1: Layout of noise receiver positions (Not to Scale) Results of Empirical Study A computer noise model of the motorway was created with The results of the tests at locations A & B and B & C are concrete and steel central reserve safety barrier, using the very similar (Table 2) and highly repeatable. The results ISO 9613² environmental noise prediction method. show that the barrier type has a negligible effect on the roadside noise levels at these receiver positions. The model used separate noise-line sources for each lane, both sides of the central reserve, 0.5 m above carriageway Results of the test at locations A’ & B’ show no significant level to represent traffic noise. difference in traffic noise levels at a greater receiver height. Noise receptors in the model were positioned at equivalent Noise Level locations to those used for the field survey and results Measurement Difference (LA10, 10min) dB Concrete Barriers and Roadside Noise Barriers and Roadside Concrete obtained with receptors at heights of 1 m, 2 m and 4 m, Location Location representing locations that receive progressively less Test Number (A -B) A B screening from the opposite carriageway. 1 89.6 90.0 -0.4 2 89.8 89.6 0.2 The model was run with concrete barrier heights of 0.6 m and 1.0 m. The steel barrier was modelled with a guard rail 3 89.6 89.8 -0.2 height of 0.15 m and top of barrier height of 0.5 m above Variation 0.2 0.4 the road surface. Location Location Test Number (B -C) B C Results of Theorectical Study 4 90.0 90.2 -0.2 Results from the theoretical analysis are shown in Table 3. 5 89.6 90.0 -0.4 This shows a negligible difference in predicted noise levels 6 89.6 89.8 -0.2 between the steel and concrete central reserve barriers, Variation 0.4 0.4 across a range of receiver heights. Location Location Difference in noise levels between the Test Number (A’ - B’) A’ B’ Receiver Concrete and Steel barriers height (concrete - steel) (dB) 7 88.6 88.4 0.2 above 5 m from road 10 m from road 8 88.4 88.4 0.0 road surface edge edge 9 88.2 88.0 0.2 (m) 0.6 m 1.0 m 0.6 m 1.0 m barrier barrier barrier barrier Variation 0.4 0.4 1 0.0 0.0 - 0.4 0.0 Table 2: Results from empirical field study 2 - 0.1 - 0.1 - 0.1 - 0.1 Theoretical Study 4 - 0.1 - 0.5 - 0.1 - 0.6 A theoretical analysis was also carried out to validate the Table 3: Results from theoretical analysis empirical results and allowed different barrier and receiver Summary heights to be considered. 01276 33160 Riverside House, 4 Meadows Business Park, Station Approach, Blackwater, Camberley, Surry GU17 9AB Camberley, Station Approach, Blackwater, Riverside House, 4 Meadows Business Park, www.britpave.org.uk The results from the empirical and theoretical studies, show [email protected] that there is a negligible difference in roadside noise levels E-mail Facsimile Website Britpave comparing concrete and steel central reserve barriers. CONCRETE STEP BARRIER Design Guidance DS/CSB/515 Concrete Barriers and Roadside Noise Prepared for Britpave by Arup.

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