Patricia Gill, Denmark Bulletin
A Shire of Denmark-commissioned traffic and evacuation management study used flawed data to determine that a second bridge was not necessary to evacuate the town in an emergency.
The Shire’s 2011 Local Planning Strategy had demonstrated the need for the second bridge but the matter was dropped in 2018 after the Shire commissioned consultants GHD to report on the matter.
In 2019 the Shire gave away $4.291 million in Royalties for Regions to build a second bridge and got back $2.5 million to upgrade Greens Pool.
The Denmark Shire Council could not decide on the site of a second bridge as part of the $14.3 Denmark East Development Precinct Project announced in 2015.
GHD’s so-called Denmark Traffic and Evacuation Management Study based increases in Denmark’s population and hence traffic volumes over peak summer and Easter holidays on sampled waste water and water consumption.
At the time of the study it was calculated that the population would increase by 600-1200 people.
But using waste water to determine visitor numbers is flawed because WA Water Corporation sewerage is only connected to the central part of the Denmark townsite.
Contrary to GHD’s calculations, Tourism WA’s Fact Sheets show that Denmark has 177,000 visitors annually, resulting in 702,000 visitor nights with an average stay of four nights.
Furthermore, 29 per cent of visitors come with caravans with the caravan park at Ocean Beach alone accommodating 3000 visitors in peak holiday periods.
The GHD study modelling demonstrated that everyone could be evacuated from Denmark via the existing South Coast Highway bridge in one and a half hours.
But turn counts were not conducted at all intersections and a time survey was not undertaken in the GHD study.
Regarding the underestimation of population increases, from 2018-2027 if there were an assumed one per cent projected growth and this reaches 1.3 per cent then by 2027 Denmark’s population will be 6800 and 7800 in 2036.
The GHD study assumes 20 per cent population (1200 people) would evacuate in one hour, subject to no traffic complication, with the 4500 evacuating in 1.5 hours.
Modelling for the study enabled the tracing of the fire front and back of queue during the evacuation and for safe evacuation to always be ahead of the fire front.
A more sophisticated modelling would include the blendings of traffic at key intersections.
In 2016, the Great Southern Development Commission drew up a business case for Royalties for Region funding for a second bridge over the Denmark River.
This was part of a project which included a new light industrial area and roadworks accounting for $7.768 million.
This was a section of an overall project and it went ahead.
Later the Shire appealed to the State Government to retain the Royalties for Regions funding for the western section of the project, to be used for the infrastructure at Greens Pool.
The overall project was budgeted at $9.696 million.
The western section included roadworks and a second bridge on a gazetted roadway where there was once a bridge and deemed important for an emergency exit, particularly in the event of a bushfire.
This article appeared in the Denmark Bulletin, 7 March 2024.
