bridge connect cross grey Inverness iron metal path pedestrian river span suspension towers walk water black care caution communicating communication crossing informing pedestrians reflective sign speed reduction street sign traffic traffic flow warning yellow blue city man pedestrian road road roads roadsign signs street town urban beside bridges foot London over parallel rail railway thames walking arch centre contemporary dundee footpath glass modern steel stylish tracks walkway cars children drivers driving flag marker motor-cars orange roadside safety school school-crossing school-zone slow-down vehicles lighting purple