The Darra to Springfield Transport Corridor took a small but significant step towards completion this morning with the turning of the first sod on the Richlands Station site.

Transport Minister John Mickel said the station was a vital part of the rail corridor's infrastructure.

"The Greater Springfield area has a population of 15,000 which is expected to reach up to 120,000 in the next 20 years," Mr Mickel said.

The four kilometre rail extension from Darra to Richlands, the new state-of-the-art station at Richlands and a five kilometre widening of the Centenary Highway to north of the Logan Motorway Interchange will be completed by 2011.

"Currently, the Centenary Highway from Richlands to Carole Park carries an estimated 26,000 vehicles per day in each direction," Mr Mickel said.

"When the Centenary Highway is duplicated in 2011, traffic volumes will have increased to almost 32,000 vehicles per day."

However, there has been some wrangling between the Government and developers over the 2015 delivery date - four years later than initially expected - for the remainder of the western rail corridor to Springfield.

The State Government originally estimated $840 million for the motorway and rail project to Springfield. However, that sum has been allocated to the Richlands rail line and Centenary Highway upgrades.

Work began earlier this year on a new 5.2 kilometre rail track between Corinda and Darra stations, costing $189 million.

Springfield councillor David Morrison previously told brisbanetimes.com.au developers and families were extremely disappointed the project had not been fast-tracked.