The Federal Roads Office is working on a plan that would see a major widening of the autoroute between Perly and Vernier just after the Bardonnex border.
The route is often jammed at rush hour with thousands of frontaliers heading in and out of Switzerland.
The aim is to build three more lanes, extend two tunnels and dig another.
64,000 m2 of forest would have to be cleared.
The plan has yet to be given the final go-ahead, but the Confederation and the canton are backing the idea.
Swiss Post announce job cuts
Swiss Post will eliminate up to 110 positions in 2027, blaming shrinking letter volumes and fewer over-the-counter transactions
Autumn arrives in Switzerland
The heatwave that has gripped Switzerland since May finally breaks tomorrow
Driver warning in Vaud
Drivers in western Vaud face four nights of disruption on the A1 next week.
Mixed results in school classrooms
Swiss 15-year-olds still rank among the world's best in maths and science, but their performance in reading and maths is sliding
Good news for household bills
Swiss households will pay a little less for electricity next year
Fuel reserves now in use
Switzerland is dipping into its emergency fuel reserves for the first time this year to keep petrol and diesel flowing
