How do engineers expand roads to create new lanes without moving the houses/businesses that already exist along the side of the road?

Question

For example, how do engineers create 6+ lanes where there were only 4 before? How are they able to create additional lanes when there are solid structures that exist close to where the old lanes were?

In: Engineering

Answer 1

Verges and footway widths can be reduced to make more carriageway widening width. Existing lane widths can be squeezed down to help with this. Any embankment side slopes can be steepened up and possibly even replaced with retaining walls to get more land within the existing highway boundary. More often than not! A combination of all of the above is implemented. The real issue is existing bridges either carrying the road or passing over. Widening these is going to be expensive and often is the reason for widening not to have happened sooner due to lack of funding.