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

clude: (1) remote modification of thesystem, (2) individual signal timing inresponse to changing conditions, and (3)highly sophisticated adaptive controlsystems, which, due to a higher level ofdata acquisition and system programming,automatically adapt to changingtraffic flows. Closed Loop Signal Systems,which are relatively inexpensiveand are becoming widely used, offer ameans of implementing planned systemtiming plans designed for a particularspecial event. Individual signals andsystem timing can be monitored andmodified remotely from a transportationmanagement center or any other locationequipped with a personal computer andmodem.The more sophisticated centrally controlledtraffic signals have a fixed communicationsystem between the trafficsignals and a control center. The trafficsignals and signal systems under controlare constantly monitored. These systemsgenerally have a higher level of programmingsophistication then the ClosedLoop Systems. Planned special eventmanagement is accommodated in muchthe same way as with Closed Loop Systems,with special timing plans beingdownloaded into the system in responseto event conditions. The timing plansare configured in advance, but as withClosed Loop Signal Systems, can bemodified from a transportation managementcenter in response to changes in thefield.Adaptive control systems represent themost sophisticated traffic signal systems.These systems require considerablymore detector input and communicationability. Adaptive control systems relyon intricate software packages to producean ever-evolving signal timingplan. These systems have the capabilityto continuously adapt to changing trafficpatterns, thus optimizing traffic flow.With adaptive traffic signal systems itwould not be necessary to downloadspecial signal timing plans in order tomanage a special event. The adaptivetraffic signal systems would automaticallyadapt to changes in traffic causedby additional event-generated traffic.• Ramp management represents a freewaystrategy that controls the amount oftraffic entering and exiting a freeway inorder to maintain or increase its efficiency.It is typically provided by meansof metering or closing ramps. The theorybehind metering is that the rate atwhich vehicles enter a freeway is controlled,reducing turbulence at rampjunctions where most congestion occurs.This, in effect, improves the efficiencyof the mainline freeway, thus reducing avehicle’s overall trip time. Ramp closureis rarely used as a long-term solution,but can be implemented when thecapacity of an entrance or exit ramp isexceeded and the resulting queues jeopardizesafety.• Lane use management is a process usedto maximize benefits and use of existingpavement, and improve the safety andefficiency of freeway operations. Laneuse management is typically exercisedthrough use of signs (static and dynamic),temporary traffic control devices,economic incentives and disincentives,and law enforcement. Lane usemanagement includes designating certainlanes for the use by a particular classof vehicles (e.g., buses, carpools), theuse of shoulders as a traveled lane duringpeak periods, contra-flow lanes, reversiblelane control, and lane use control.Lane use control uses dynamic4EVENT PROFILE POST-EVENT ACTIVITIES DAY-OF-EVENT ACTIVITIES ADVANCE PLANNINGOVERVIEW4-31