The plan to build a new footbridge next to the Mont-Blanc bridge could be scuppered by a referendum.
The CHF 40m project has been passed by the city council. But some consider the idea to be unnecessary and too expensive.
Campaigners now have less than a month to collect 3,200 signatures.
Despite the threat of a referendum, work has started. The city has already launched a call for tenders for wooden piles needed for the construction, valued at half a million francs.
Your pictures of the eclipse
You sent in your pictures of the eclipse - many thanks
Copernicus reports hottest summer ever measured
Switzerland is in the grip of a level 3 heat alert, with Geneva heading for temperatures of up to 36°C on Friday.
Tough new banking rules possible
The Federal Council has launched consultations on new banking rules that could withhold or claw back bonuses from top banking executives.
Speed crackdown affects all of Switzerland
The Federal Council has tightened the rules for imposing 30 km/h zones on city streets, requiring cantons to prove that a slowdown will not push traffic into residential neighbourhoods
Back to school concern over heat
Vaud is preparing to map every school building in the canton to identify the classrooms most vulnerable to extreme heat
Eye warning for eclipse watchers
Anyone who watched Wednesday's solar eclipse without proper glasses should watch for signs of retinal damage, doctors are warning
