signal are Austria, Belgium, Estonia, Finland, Great Britain, Hungary, Netherlands, Norway, Mexico, Poland, Russia, Spain and Sweden. France, Portugal and Switzerland make limited use of flashing green. Pedestrian red-amber In Massachusetts, simultaneous red and yellow lights in all directions allow a pedestrian to cross diagonally. This replaces the extra "WALK"/"DON'T WALK" or white Ampelmanchen/hand signal, but is in violation of the MUTCD. This practice is obsolescent but it remains in the Massachusetts driver's manual. Signage In the UK, signs can be affixed to a signal head to emphasise a regulatory traffic sign. The most common use for these is prohibited turns. Special signals Transit priority signal In Oregon, Ontario, Quebec, British Columbia, Nova Scotia, Manitoba and Alberta, traffic signals may also have an extra white rectangular light mounted above the red light. This phase indicates that a public transit vehicle may proceed through an intersection in any direction while all other traffic faces a red light. In some areas such as Boston, Massachusetts and Denver, Colorado a trolley may have its own traffic signals, indicating that it is okay for it to cross an intersection. These signals are all white, and the top section (stop) is a horizontal bar, the middle (caution) is an upright triangle, and the bottom (go) is a vertical bar. The horizontal bar is generally considered the "red" phase and symbolizes traffic flowing across the intersection from the perspective of the tram. In Australia and New Zealand, buses and trams may have a white "B" and "T" light respectively to indicate they may proceed through the intersection in any direction. A white arrow indicates that they only may proceed in the arrow's direction, common for trams to indicate that they may proceed and the points are set for proceeding that direction. Transit signals may be accompanied by red and yellow B/T signals indicating to buses and trams stop and caution respectively. Along the northern half of Hong Kong Island, there is a similar "T" lamp in yellow for double-decker trams. Singapore uses a similar "B" light for buses, but it is green. In many parts of Western Europe transit signals (for trams, and in some cases buses as well) employ traffic signals that are phased similarly to main traffic signals but replace the green light with a vertical white bar, the red light with a horizontal white bar and the yellow with a white dot or