The Southern Interchange Compound tunnel shaft will be 30 metres deep. The on ramp entry to the tunnel will be 12 metres deep. 

The Wilson Road Compound tunnel shaft will be 90 metres deep. 

The Trelawney Street Compound tunnel shaft will be 57 metres deep. 
 
The Northern Interchange Compound tunnel shaft will be 44 metres deep. 

Once the required depth is reached, excavation machines called roadheaders will be lowered into the shaft. The excavated rock is then transported from the tunnel to the surface by a conveyor belt and removed off site by trucks.