"Our proposal would allow manufacturers the flexibility to design different sounds for different makes and models while still providing an opportunity for pedestrians, bicyclists and the visually impaired to detect and recognize a vehicle and make a decision about whether it is safe to cross the street, " said NHTSA Administrator David Strickland.
They said "forward visibility around the wall of St Peter's churchyard is considerably substandard", and a "proposal to signalise the clocktower junction would necessitate departures from national design standards, which may potentially compromise safety".
Govan insists Zumthor's design isn't written in stone, and that there's room for a public voice in a proposal that would give new vision to public art.