Driver’s Manual | 29 WARNING SIGNS: DESTINATION SIGNS: Work Area Signs SERVICE SIGNS: TRAFFIC SIGNALS Traffic Lights COLOR: Yellow,  with black letters or  symbols MEANING: You are  approaching a haz- ardous location or a  location where there  is a special rule, as shown in the sample signs.  Sometimes a warning sign is joined with a yellow  and black “recommended speed” sign. This indi- cates reduced speed is advised in that area.  COLOR: Green, with white  letters MEANING: Show the direction and distance to  locations. COLOR: Varied. MEANING: Indicate interstate, U.S., state or county routes. The shape tells you the type of  route you are on. The sample signs, left to right,  are for state, U.S., and interstate routes. When you  plan a trip, use a highway map to decide which  routes to take. During the trip, watch for destina- tion signs so you will not get lost, or have to turn  or stop suddenly. COLOR:  Orange, with  black letters or symbols MEANING: People are at work on or near the  roadway and traffic can be controlled by a flag  person. A work area speed limit as low as 25 MPH  (40 km/h) can be posted. Even if no speed limit  is provided, you must drive at a reduced speed  through the work zone and you must always obey  the flag persons. These illustrations show some  signals a flag person will use. Know and obey them.  COLOR: Blue, with white letters or symbols MEANING: Show the location of services, like rest areas, gas stations, camping or medical facilities.  Some are round, and some are arrows. State law  requires that if the traffic lights or controls are out  of service or do not operate correctly when you  approach an intersection, you must come to a  stop as you would for a stop sign. You must then  continue according to the rules of right-of-way,  unless you are told to continue by a traffic officer. Route Signs STOP SLOW PROCEED Traffic lights are normally  red, yellow and green from  the top to bottom or left to  right. At some intersections,  there are lone red, yellow  or green lights. Some traffic  lights are steady, others flash. 