I'd suggest a bell on the bike.
My main use of the bell is to warn pedestrians on the bike path I'm behind them.

Also at the moment, even here in Europe, the bike path is just that, a path. As far as I'm aware no local authority has yet had the guts to build or even plan a bicycle 'freeway'

Many flat cities could easly have bikeways built, all that would need to be done if for a small but straight and flat road to be re-surfaced and marked and have all the motor powered vehicles banned.

Only HPV's (Human Powered Vehicles) or other wheeled pedestrians would be permitted, so skates and wheelchairs would be OK, one might insist that things like baby buggies and pushed wheelchairs are permitted, but have to travel in the slow lane (like freight on a motorway)

The bikeways, like the car motorways, would have three lanes in each direction which would be wide enough for a recumbent or trike, and only overtaking (not undertaking) would be allowed. They could even go as far as putting a roof over the bikeway.

Cost would be minimal, savings vast. However it needs vision, something that no polotician has.