This app provides traffic flow maps for the Seattle, Tacoma and Olympia area and allows you to pick your own colors for traffic conditions.
Being able to choose your own colors is beneficial for those who have a color vision deficiency. One who is color vision deficient has a decreased ability to see color, or perceive color differences. This is potentially problematic if you are trying to differentiate traffic conditions on a map based on a color scheme.
By tapping the gear icon in the upper left corner of the menu screen you have the ability to customize the colors which are used to display traffic conditions.
Traffic conditions are cached on your phone for three minutes before a manual refresh will fetch updated data from the server.