ABA warns on Tx issue

State planning agencies “should be sensitive to the risks of allowing urban encroachment onto the remaining metropolitan AM radio transmission sites across Australia,” according to the Australian Broadcasting Authority. The ABA’s warning comes as a result of the recent trouble over housing developments being built too close to transmitters.

ABA Chairman David Flint told radioinfo: “Suitable AM radio sites in and around major cities are few in number and extremely difficult to replace without affecting the coverage area of what the listening public regards as essential services.”

The ABA has no direct role in the selection of radio and television transmitter sites. Broadcasters negotiate about their sites directly with local planning authorities. But the ABA is responsible for coordinating radio signals to minimise their interference.

“Our engineers have planned carefully and signals are tightly packed, especially around cities. Moving a transmitter changes the area its signal covers. This often leads to new interference with other broadcasts. Because of the way they travel, AM signals sometimes even need international coordination… There are many pressures on city planners, but broadcasting services are an important part of most people’s lives. The ABA is concerned that state and local governments may not appreciate the scarcity and value of the existing sites.” says Flint.

Ground conductivity has a major impact on how well AM radio waves are launched and salt water is considered to provide the best conductivity. AM radio transmitters are therefore often built in swampy areas, that have not historically been desirable for residential use. Cities have grown, “but if housing developments crowd out the broadcasting sites it will be difficult to find alternatives.”

The ABA’s comments have been prompted by the development of major residential projects in close proximity to the AM transmission towers at Homebush Bay as a part of the Sydney Olympic Park master plan. “The situation at Homebush highlights the continuing challenges facing AM broadcasters in congested metropolitan areas,” according to Flint.

A recent engineering survey on the levels of electromagnetic radiation (EMR) from the Homebush sites to the (as yet unoccupied) Waterside apartments has recommended the re-siting of the transmitters. While the ABA is already working with the affected broadcasters and will give high priority to any move, it could be “extremely difficult to find a suitable alternative site and technical specifications.”

Neither the broadcasting licensees nor the relevant Federal regulatory authorities (the ABA and the Australian Communications Authority) have any authority over the actions of local and State town planning authorities.

The ABA and the Australian Communications Authority have “met with those stakeholders affected by the proposal that the AM radio sites at Homebush move further away from the new Waterside residential developments at Olympic Park.” The developments are due to be occupied in August-September 2003.

The broadcasters and regulators “raised the issue with Planning NSW over a year ago, when the proximity of the new residential developments became known.” The broadcasters have been considering possible alternative transmission sites to serve the Sydney area since prior to the Olympics, and in 2001 had objected to the Sydney Olympic Park post-Olympic master plan.

In a connected matter, part of the Waterside residential development is said to be within the ‘drop zone’ of the 145 metre 2UE and 2SM broadcasting tower structure, the area potentially at risk if it fell over. The two transmission towers of a Brisbane AM station, 4BH, fell over in August 2002, as a result of vandalism.

The levels of EMR at all broadcasting transmission sites are the responsibility of the relevant broadcasters and site owners. The aggregate powers of more than one service may exceed permitted levels, even though a single service does not.

In the chronology of events leading up to this current situation the following is known to have taken place:

The Sydney commercial AM radio broadcasters wrote to the NSW Department of Urban Affairs and Planning in September 2001, expressing concern at not being asked to comment on the Olympic Park post-Olympic master plan, indicating the potential health and safety risks associated with the proposed developments and noting the impact on possible day/night switching power increases.

In February 2002 2UE wrote to the ABA, reiterating these concerns, and the ABA met with the ACA, with the ACA agreeing to coordinate responses on this issue.

The ACA wrote to the Sydney Olympic Park Authority (SOPA) in April 2002, expressing concern at the proximity of new residential developments to high electromagnetic fields existing in the vicinity of Homebush Bay AM transmission facilities. The ACA was concerned at the potential for substantial interference to electrical and electronic devices that may cause malfunction of equipment and the possibility of health exposure implications.

SOPA and Planning NSW first met with the ACA, ABA and the broadcasters in June 2002 to discuss the issue and have met with the stakeholders periodically since then.

The ACA expects to mandate new transmitter licence conditions specifying a new radiation protection standard for EMR on 1 March 2003. Compliance by broadcasters with the existing EMR standard is only advisory.