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

6-56 shows a permanent CMS over an arteriallocated adjacent to a stadium venue andserving venue parking areas.to a central management point, making thema very attractive and flexible tool.Portable signs are usually located at the sideof the road and do not sit as high as an overheadsign, which can impair drivers visibility.Most are 3-line, 8 or 9-character signs,and although most have the capability ofdisplaying multiple phases, they tend to beused with simple short messages to allowdrivers to read and comprehend the message.Highway Advisory RadioFigure 6-56Permanent CMS Over Stadium Access RoadA CMS should not compete with existingroadway signs. In general, a CMS should bepermanently installed at the following locations:• Upstream from major decision points(e.g., exit ramps, freeway-to-freeway interchanges,or intersection of majorroutes that will allow drivers to take analternate route)• Upstream of bottlenecks, high-accidentareas, and/or major special event facilities(e.g., stadiums, convention centers)• Where regional information concerningweather conditions such as snow, ice,fog, wind, or dust is essentialPortable CMSThe use of trailer-mounted CMSs providesan agency with a great deal of flexibility.The signs, which are typically much smallerthan permanent, over-the-road CMSs, areused most commonly for temporary applications.As such, portable CMSs are verysuitable for special event management.They are usually diesel- or solar-poweredand use wireless (cellular) communicationsAlthough not as widely used as changeablemessage signs, highway advisory radio isanother means of providing highway userswith information in their vehicles. Traditionally,information is relayed to highwayusers through the AM radio receiver in theirvehicles. Upstream of the HAR signal, usersare instructed to tune their vehicle radios toa specific frequency via roadside or overheadsigns. Usually, the information is relayedto the users by a prerecorded message,although live messages can also be broadcast.Highway advisory radio is an effective toolfor providing timely traffic and travel conditioninformation to the public. It has variousadvantages and disadvantages. Its most importantadvantage is that it can reach moretravelers, or potential travelers, than theother roadside technology, changeable messagesigns. While CMSs reach only thosemotorists at a particular point, and can onlyconvey a short message, HAR has the advantageof being able to communicate withany person in the HAR broadcast range.Furthermore, the amount of information thatcan be conveyed to the user is much greater.Its primary disadvantage is that it is restrictedto low power, and this can lead topoor signal quality (since many outside6-64