This invention concerns a portable processing device 200, such as a navigation device, comprising a positioning device 250,251 for determining a position of the processing device 200, an audio and/or visual output device 240/261, a processor 210 and memory 230 having stored thereon map data. The processor is arranged to determine a position on the map data based on an output from the positioning device 250/251, determine a speed to travel to arrive at a traffic control signal, which switches between two or more conditions to indicate a right of way, when the traffic control signal has a particular condition and cause the audio and/or visual output 240/261 to output an instruction to indicate the determined speed to travel. The invention also concerns a server 302 for interacting with the portable processing device 200.
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