managing travel for planned special events - FHWA Operations ...

or venue access route. These are temporarysigns, mounted on fold-away supports, alongthe shoulder of the roadway or at exit goresto direct motorists to alternate routes as amatter of typical traffic management or inresponse to an incident and redirecting oftraffic.Changeable Message SignsOne of the most fundamental technologiesavailable for disseminating traffic-relatedinformation from the roadside is that ofchangeable message signs. CMSs are sometimesreferred to as dynamic message signsor variable message signs. CMSs are programmabletraffic control devices that canusually display any combination of charactersto present messages to motorists. Thesesigns are either: (1) permanently installedabove or on the side of the roadway, (2)portable devices attached to a trailer, or (3)portable devices mounted directly on a truckand driven to a desired location. PortableCMSs are much smaller than permanentCMSs and are oftentimes used in specialevent situations, highway work zones, whenmajor crashes or natural disasters occur, andemergency situations.When installed, CMSs become a part of thetotal motorist information system. Thus theinformation presented on CMSs and theplacement of the signs must be consistentand compatible with static signs. Highwaysigns – both static and dynamic – must projecta message so that the driver can:1. Detect the sign,2. Read and understand the sign,3. Make appropriate decisions based on theinformation gained from the sign, and4. If necessary, initiate a control response,and complete the required maneuver.CMSs perform a critical role in special eventmanagement. Such signs can furnish motoristswith real-time information that advisesthem of a problem and in some cases, a suggestedcourse of action. CMSs are also usedto improve motorist safety and reduce trafficcongestion and delay during events. CMSscan be used to manage traffic by displayingthe following types of messages:• Early warning messages give motoristsadvance notice of slow traffic and queuingahead and are effective in reducingsecondary crashes. When used in freewaywork zones, early warning messagesalso give notice of new detours,changes in alternate routes, changes inlane patterns, special speed controlmeasures, etc.• Advisory messages provide motoristswith useful information about a specificproblem along their route. This informationallows motorists to change theirspeed or path in advance of the problemarea, or may encourage them to voluntarilytake an alternate route to their destination.• Alternate route messages influence motoriststo travel to their chosen destinationby using different routes than originallyintended. The alternate route isone designated by the transportationagency. In cases when the freeway isphysically closed as a result of construction,crash, or natural disaster, the motoristsare notified that an alternate routemust be used.The most critical locations for installingpermanent CMSs are in advance of interchangesor highways where drivers have theopportunity to take some action in responseto messages displayed on CMSs. In manyspecial event cases, permanent CMSs arealready strategically located to advise eventpatrons of special conditions and non-eventmotorists of alternate bypass routes. Figure6EVENT PROFILE POST-EVENT ACTIVITIES DAY-OF-EVENT ACTIVITIES ADVANCE PLANNINGOVERVIEW6-63