In Zurich, voters cleared plans to lengthen the airport runways.
The airport says the runway extensions are needed to cut back on delays and it will reduce noise.
The move was backed by many parties and the cantonal government. But detractors say it will increase noise, traffic and pollution.
The CHF 250m cost will be paid in full by the airport.
61.7% gave the go ahead on a relatively high turnout of 57.6%.