Marshall Day Acoustics has extensive experience in all aspects of transport noise control and assessment, including:

• Assessment of environmental noise impact
• Design of noise barriers
• Architectural and town planning studies
• Insulation of dwelling facades
• Development of transport noise policies and national Standards
• Review and validation of transport noise prediction models

Assessment of Environmental Noise Impact:

Marshall Day Acoustics has prepared noise impact assessments for the majority of roading projects in New Zealand and Victoria, Australia. We have developed an assessment method which quantifies impact in terms of community effects such as sleep disturbance, interference with speech communication and annoyance. 

Of particular concern is the response of communities subject to changes in noise environment. Studies have shown that the response is often much greater than would be predicted from the steady-state models, and that the response can be very long-lived amongst people living in the area at the time of the change.

Road Traffic Noise Control Design:

We have developed a risk analysis approach to noise barrier design which has led to cost-effective noise barrier solutions on several major projects. Risk analysis allows a clear discussion concerning safety factors to take place between the Road Authority, the road builder and other stakeholders.

We have an extensive knowledge of noise barrier designs, including absorptive barriers, coarse-edge barriers, absorptive-edge barriers and curved designs, as well as fully-enclosed and semi-enclosed designs.We have provided acoustic advice on several projects where innovative approaches to noise control were implemented, such as Herriott's Glen, where the Quiet House Concept was employed.

Review and Validation of Road Traffic Noise Prediction Models:

Marshall Day Acoustics has been involved in all aspects of the prediction of environmental noise, including software development, software beta testing, validation of prediction methods, and, of course, use of the various models for the design of noise control measures.We pioneered the use of 3-dimensional computer models for the prediction of environmental noise and have moved on to provide distribution and technical support for one of the world's most sophisticated noise prediction software packages, SoundPLAN.

In Australia, we undertook an extensive research & development project for VicRoads, in which we reviewed over 30 software packages and 18 traffic noise prediction methods, evaluated 3 methods in detail and calibrated one method, the new US Federal Highway Administration FHWA TNM method, for use in Victoria.

Road Traffic Noise Policy Development:

Marshall Day Acoustics' extensive experience in noise prediction, measurement, assessment and control provides an invaluable basis for our work in environmental noise policy development. We have assisted the local Road Authority, VicRoads, both as consultants and as colleagues, in the review and development of their Traffic Noise Reduction Policy.

Recently, we were selected by Austroads (the national body responsible for coordinating State Road Authorities) to prepare a brief to develop a National Approach to Road Traffic Noise Management. One important aspect of noise policy, the management of noise modelling outcomes, will be assisted by the new Guide to the Validation of Road Traffic Noise Models, prepared by Marshall Day Acoustics for Austroads.

As representatives of the New Zealand Acoustical Society, Marshall Day Acoustics' staff have also played a significant role of the committee developing Draft New Zealand Standard DZ 6806 Acoustics – Road traffic noise – New and altered roads