Dynamic & Variable Message Boards What factors are considered in selecting locations for dynamic message signs and for the length of a message?
Rhode Island’s RhodeWays Program has deployed 15 overhead dynamic message signs (DMS). These signs are located based on decision points, i.e., ahead of a location where a motorist may be able to divert and/or make a decision to stay on a roadway impacted by an incident. Motorists are given about 60-90 seconds to read a sign and make a decision. Since there are standard static signs on our freeways already, new dynamic sign installations must not interfere with pre-existing signs. Recognizing that motorists must read and react to the signs is factored into the number of lines used to display information and to determine flash speed between messages. In Rhode Island, we attempt, whenever possibile, to minimize the distraction the sign may cause by keeping the messages to two lines and one panel. If we have have to display a multi-panel message, we keep minimize the flash to the following: 1 line – 3 seconds between messages; 2 lines – 4 seconds between messages; 3 lines – 5 seconds betwe
