A lot according to Nowra man Bill Hancock, who has taken Transport for NSW to task over figures regarding the number of motorists crossing the Shoalhaven River bridges each day.

Routinely, whenever the South Coast Register does stories on the proposed new $342 million Nowra bridge crossing, or when politicians talk about the project, either in person or in press releases, the figure always presented is that 50,000 cars cross the Shoalhaven River each day.

But Mr Hancock said the Traffic NSW Traffic Volumn viewer (online), tells a different story.

"When you actually check the figures, the number of cars travelling both north and south in the last fully completed count in 2018, adds up to 48,461," he said.

"However, when you hover over the river counting area on the website, the figure 74,252 comes up.

"When you add the actual data up - northbound traffic 23,9476 and southbound 24,514 it actually only ads up to 48,461. A difference of 25,791.

"Is that 74,000 figure a mistake? 25,000 plus is a pretty big mistake?

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"It just doesn't add up. The actual figure is 602 less than 2016 and 2432 less than 2017.

"The 74,252 figure is a 46 per cent increase on 2017.

"I just wonder by what actual figures are we going by?"

He said even Infrastructure Australia, who recently upgraded the new Shoalhaven River crossing, as a "priority project" stated more than 51,000 vehicles use the crossing every day.

Yet when you go back through the data on the website the figures don't stack up - 2011 - 45,718; no data between 2012-2014; 2015 - 48,501; 2016 - 49,063; 2017 - 50,893; 2018 - 74,252.

"Interestingly in 2019 the recording of northbound vehicles stopped," Mr Hancock said.

"Southbound vehicles numbers were 25,337 - that's an increase of 823 on the 2018 data, which is in question anyway.

"But there is no data for northbound. Why?

"They [Transport for NSW - previously RMS] say that 80 per cent of the 50,000 vehicles per day over the bridges is local traffic, that's 40,000.

"They conclude a bypass would not make much difference.

"If, as their own figures show, the real daily count is 74,252 vehicles per day, wouldn't it be fair to say that there is still only 40,000 that are local.

"In that case 34,252 vehicles per day are through traffic, that's 46.12 per cent and that makes a big difference.

"It also sounds more realistic!

"Locals living here know the traffic chaos. It is nothing to have the southbound Princes Highway traffic backed up past Bomaderry McDonalds around 9am each morning.

"That's normal weekday traffic not holiday times."

He questions how the new bridge and associated intersection upgrades would alleviate traffic congestion in the area.

"Once you get over the three southbound lanes and four northbound lanes of the bridges it reverts back to two lanes," he said.

"We do need the western bypass, I think they are playing with numbers to make a case for not spending the money where it is needed.

"Are we having the wool pulled over our eyes?"

Transport for NSW was contacted for comment.