Clem7 tunnel forecaster Maunsell Aecom gains indemnity

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Traffic forecaster Maunsell Aecom gained an indemnity from RiverCity restricting its liability to $500,000, if it were to be successfully sued by a third party over its forecasts.

Maunsell was paid $2.5 million for its qualified forecast that more than 60,000 vehicles a day could be using Clem7 within a month of opening and 90,000 after six months.

Five months after opening, the tunnel is being used by just over 27,000 vehicles a day, despite the toll for cars being cut to $2 against a projected charge of $4.28.

RiverCity this week wrote down the value of its operation by a staggering $1.56 billion.

Investors, who collectively pumped $740 million into RiverCity in 2006, have seen their $1-a-unit investments slide to just 1.9¢ each.

Some are talking of legal action, but have not yet begun formal proceedings.

Industry observers say the failure of the Clem7 usage forecasts highlighted the fact that, in the words of one, "traffic forecasting is a black box", which relied on highly complex computer modelling and hundreds of assumptions.

"Transport modelling sounds like a science but it's more of an art," Griffith University urban management academic Dr Jago Dodson said.

He said it was also hard for outsiders to audit the modelling because of its highly technical nature.

"Relatively few people have the skill to evaluate it and those who do tend to work for government or private consortiums," Dr Dodson said.

Maunsell, in RiverCity's 2006 prospectus, said it believed its forecasts were "based on sound inputs and appropriate modelling processes and (were) reasonable for the assumptions made in the modelling".

It said, however: "Traffic volumes set out (in) this summary letter are forecasts only and there can be no guarantee that the projected volumes or other outcomes will be achieved."