alert
attention
background
barrier
black
blue
bright
buses
caution
city
construction
danger
design
direction
equipment
forbidden
gap
gate
give way
icon
information
isolated
london
mind
notice
plate
red
road
safety
security
shape
sign
signal
site
stop
street
striped
subway
symbol
traffic
transport
travel
tube
underground
urban
warning
way
way out