Practices in One-Lane Traffic Control on a Two-Lane Rural Highway (2018) / Chapter Skim
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Pages 104-114
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From page 104... ...
104 This appendix provides a literature review of studies focused on 1L2W TTC zone traffic analysis, with a focus on delays and capacity and including the use of manual flagging or signal (TTCS) controls.
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From page 105... ...
Traffic Analysis for 1L2W Operations 105 In a further study, a stochastic method to predict 1L2W TTC zone vehicle delay was proposed and validated by Cassidy et al., replacing their previously proposed deterministic queueing techniques (Cassidy et al.
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From page 106... ...
106 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway where di = average queueing delay per vehicle traveling in direction i, Gi = effective green time in direction i, C = cycle length, qi = traffic demand rate in direction i, and Si = saturation flow rate in direction i. • The total average TTC zone delay: (2)
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From page 107... ...
Traffic Analysis for 1L2W Operations 107 in the evaluation and were achieved using MS Excel spreadsheets and micro-simulation. Results showed that TTC zone closure length and average delay per vehicle were positively correlated for all four traffic control strategies, as shown in Figure A-1.
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From page 108... ...
108 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway v = traffic volume, s = saturation flow rate, and HVi = heavy vehicle percentage for direction i. The queue length was estimated as 0.616983 % 0.598965 % 0.0006855 0.299197 0.003199 (4)
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From page 109... ...
Traffic Analysis for 1L2W Operations 109 where c1 = the directional capacity of 1L2W TTC zone (passenger car unit/s) ; s1 = saturation flow rate in direction 1; g1, g2 = effective green time in direction 1, 2; l = TTC zone length; V1, V2 = vehicle speed within TTC zone in direction 1, 2; and L = total lost time (including start-up lost time and clearance lost time for both directions)
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From page 110... ...
110 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway Site No. TTC Zone Length Control Methods 1 Short (0.1–0.5 mi)
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From page 111... ...
Traffic Analysis for 1L2W Operations 111 placed at the entrance and exit of the open single lane, a signal controller, and a portable set of traffic signals. The signal control algorithms maintained an optimal cycle time and splits, with the optimization objective being the minimization of total delay.
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From page 112... ...
112 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway length decreases when the combined flow rate increases. The optimal clearance time decreases and the total discharge time increases as the combined flow rate increases.
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From page 113... ...
Traffic Analysis for 1L2W Operations 113 To determine the timing of TTCSs, these factors need to be considered: • Length of TTC zone (which may have to be separated into smaller jobs) , • Number and variability of vehicles expected to approach each end of the TTC zone, • Speed of traffic approaching each end of the TTC zone, • Range of speeds within the TTC zone, and • The amount of buffer time used to separate exiting traffic from entering traffic.
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From page 114... ...
114 Practices in One-Lane Traffic Control on a Two-Lane Rural Highway • Extension interval (actuated operation) uses 2.4 seconds or 3 seconds if controller only accepts integer.
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