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

forces affect the signal, such as weather)and, therefore, poor listener levels.HAR can be broadcast in two ways: Point orWide-Area coverage.HAR is an element of the Federal CommunicationCommission’s (FCC) Traveler InformationSystems (TIS) designation. Theyare permitted under strict FCC guidelinesand regulations associated with technologyand operations. They are licensed as a secondaryuser, which means simply that theycannot interfere with a primary user, i.e., acommercial broadcast station. As a secondaryuser, HAR broadcasts are restricted insignal strength, a level that limits theirtransmission range to no more than three orfour miles from the transmitter. A numberof technologies are available for HARtransmission, using both AM and FM bands.Typically, HAR has been implemented using10-watt AM transmitters. This is because,beginning in 1977, it was the onlytechnology permitted by the FCC for travelerinformation. As such, this technologyimplementation has also proven to be themost effective. Other means involve verylowpower AM transmission, where multipletransmitters are spaced closely together toform a large area of coverage. This application,however, has not proven very successful.As late as 2000, the FCC ruled to allowthe use of low-power FM transmission forTIS. This technology has limited applicationto-date.Urban areas typically present a unique set ofchallenges to HAR application, which canhinder downtown event management. Tallbuildings present an obstacle to uniformtransmission since the FCC restricts antennaheight to approximately fifty (50) feet.High-power electric lines can incur noise onthe transmission that negatively impactsbroadcast quality.Deployment Strategies• In Point broadcast, a single transmitter isused to broadcast over a given area.This is typically used at diversion pointsin advance of areas of recurring congestionto notify motorists of queues andcongestion. This type of implementationis popular with travelers because the informationis specific to them. This is themost common application for HAR, andit typically utilizes 10-Watt transmitters.It is the simplest to manage in terms ofequipment to maintain.• Wide Area Broadcast transmits a signalto a larger coverage area using multiplesynchronized transmitters. This is an effectivestrategy when a single message isapplicable to a large coverage area andthe coverage area is sufficiently large fora motorist to hear the longer messagelength. The fact that a long single message,that is pertinent to specific travelersfor only a part of the message, is indeeda disadvantage. Studies haveshown that travelers want brief, specificinformation, pertinent to their locationand situation. They are not likely to listenfor long periods of time until their informationis broadcast. Technically,synchronization is difficult to accomplishbetween transmitters because boththe time and repeated voice signal mustbe in sync.Both of these applications are practical andviable for planned special event management.Portable and Mobile SystemsPortable systems permanently installed ontrailers and mobile systems installed on serviceor maintenance vehicles can be of valuein providing timely dissemination of infor-6EVENT PROFILE POST-EVENT ACTIVITIES DAY-OF-EVENT ACTIVITIES ADVANCE PLANNINGOVERVIEW6-65