Human response to vibration in residential environments (NANR209), technical report 4: calculation of noise exposure
- Publisher: Defra
Although vibration is the primary focus of the “Human response to vibration in residential environments” project, it can be seen in the literature that noise, which covariates very well with vibration, can facilitate annoyance. Work was done towards analysis of vibration exposure and noise exposure separately, as was analysis of the combined effect from both. In the report Human response to vibration in residential environments, an analysis of combined effects from noise and vibration is performed.\ud The objectives of this technical report were to obtain internal and external exposure to noise in residential environments for three separate sources; railway traffic, construction work and internal sources. As such, exposures were obtained in two steps. In the phase one, external measurements and estimation were performed in the absence of internal measurements. In the phase two, exposures over 24h were calculated for railway traffic. Additionally, owing to the nature of construction occurring during the daytime period, only daytime (rather than 24h) exposure from those sources was calculated.\ud Exposure to noise from railway traffic was obtained from calculation of Lden based on the Calculation of Railway Noise guidelines (Department of Transport, 1995). This noise descriptor was used for the assessment of railway noise as residents are exposed over a 24h period. On the other hand, for a determination of exposure to noise from construction activities a noise descriptor such as LAeq,0700-1900 seems to be adequate as only daytime activities were observed and recorded during measurements. Details of determining the exposures are explained further in this report.\ud Calculation was performed for all residents for whom vibration exposure was measured. Predictive procedures were chosen due to the absence of a significant number of external measurements. This is a well known standardised routine, although it requires many details regarding train type, the number of vehicles that a train is composed of and noise emission from a particular vehicle. All details about trains were obtained from sources below:\ud • Control positions used for the monitoring of vibration from railway traffic for 24h\ud • Timetables obtained from the National Rail Enquiries website\ud • Freightmaster - a guide to rail-borne freight services in the country (Freightmaster, 2011)\ud • Two Line Speed Profile reports from 2005 and 2009 (Goffey, 2005; Moor, 2009)\ud Exposure from construction work was calculated from measurements. Some activities were unable to be captured successfully. Such problems were encountered mostly due to anninability to anticipate the schedule of construction work as well as frequent changes to any pre-existing schedule. Consequently, an estimation of these construction activities was provided instead.\ud A significant number of limitations was encountered during internal measurements of noise from railway sources. As explained in detail in Section 3.2, the primary noise source of interest was often easily masked by extraneous internal sources. Consequently, poor results of many events or no events were obtained at all. External measurements however yielded clear, comprehensive and distinct events, identifiable over background noise.\ud Secondly, a number of problems during measurements of construction sources were encountered. One of the main problems relates to the very strong influence of background noise. As a result, noise measurement was significantly contaminated, particularly by road traffic. Activities such as saw-cutting, excavation, flattening, etc. that occurred in the East Manchester site have greater uncertainties associated with obtained results. On the other hand, the South of Manchester site was situated at an increased distance from road traffic and thus fewer uncertainties were expected for the construction activities identified.\ud Another problem, addressed above for rail noise, is that encountered when performing internal measurements. As such, only external measurements were performed. However, an internal exposure was estimated from an external exposure. There is a good correlation between external and internal exposure.