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Safety ImpactsMetering can improve safety by breaking upplatoons entering the freeway Reduces turbulence in merge zones Accident rate reductions of 20% to 40% havereportedLeads to reduction in non-recurring delay

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Freeway Impactsy Freeway speeds typically improve by 5% (over 15%

assuming throughput increase)y Shifts delay to ramps - typical meter delay of 2 to 5

minutesy Total hours of travel remains relatively constant

(0% to 5% change)y Expect improved travel time reliability y Longer trips most likely to benefit the mosty Can increase maximum throughput (5 to 15%)

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A rterial Impactsy Q ueue impact mitigated through design and operating

considerationsy Improved freeway operation can divert longer trips to the

freeway y Potential for diversion to arterials is limited:y Short queues and meter delaysy Lack of alternative route in many casesy Short trips most likely to diverty is this a benefit?y Can discourage ramp-hopping around bottlenecksy Where practical, integration of metering and local signaly systems should be pursued

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How It Works

http://www.stancog.org/pdf/ramp-metering-hov-lane-study.pdf

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R ec e ti s

I le e t ti Acti sy Incorporate ramp metering elements into other

planned improvementsy Local jurisdictions and Caltrans should establishcooperative policies for the management of the

ramp metering:y Establish a process to ensure that future concerns

of local agencies are addressedy Determine how intersection impacts would be

identified and resolvedy Define system integration requirements

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Pic ture of Ramp Meter

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Pic ture of Ramp Meter

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R amp Acceleration Distance is a critical Design IssueMinor Arterial Congestion

Crossing Arterial Congestion

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http://www.ite.org/meetcon/2007AM/Session_36_Marion%20Waters.pdf

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