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40 Cards in this Set
- Front
- Back
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5 general principles of the MUTCD
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fulfill a need, command attention, convey clear, simple message, command respect of road users, give adequate time for proper response
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3 critical aspects of traffic control devices addressed by the MUTCD
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standards for physical design of the device, specifying shape, size, colors, legend types and sizes, 2-where devices should be located, 3-warrants that justify use of a particular device
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4 different categories of the legal aspects of the MUTCD
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standard, guidance, option, support
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4 mechanisms to convey messages to drivers by traffic control devices
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color, shape, pattern (such as double yellow or dashed), legend (words on signs)
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shall, should, and may used in the MUTCD – their implications
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standards use shall, guidances use should or should not, options use may or may not
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MUTCD
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Manual on Uniform Traffic Control Devices
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semi-actuated control
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used where small side street intersects major street, two phase with all turns permitted
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full actuated control
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all lanes of all approaches monitored by detectors, cycle lengths subject to variation, accommodates multi-phase
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volume-density control
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same as full actuated with additional demand response features
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gap reduction
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smaller gaps required as time progresses in order to maintain green for the phase
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6 Features and operations of actuated signals
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min. green time, passage time (PT), max green time, recall settings, yellow & all-red intervals, pedestrian WALK
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6 components of the HCM 2010 signalized intersection models
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input module, define movement groups and adjusted flow rates, compute lane group flow and saturation flow rates, input or compute phase duration, compute capacity, compute performance measures
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difference between critical lane and critical lane group concepts (24.2.1)
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HCM uses critical lane instead of lane group since it accounts for unequal use of lanes through a process of adjustments to saturation flow rates
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Effect of changing offsets (26.3
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changes bandwidths
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Potential problems of coordination (Course notes)
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increasing bandwidth efficiency in one direction could decrease efficiency in another
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bandwidth
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time difference between the first and last vehicle that can pass through the entire system without stopping
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common types of progression (26.6)
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simple, forward, flexible, reverse
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bandwidth efficiency
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bandwidth / cycle
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how max green is timed
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begins when there is a "call" on a competing phase
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how min green may be estimated for point or presence detection (2 equations)
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Gmin = start-up lost time + 2 * int(dist between STOP line and detector / 25)
Gmax = start-up lost time + 2 * number of veh stored in detection area |
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point detection passage time is the same as...
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PT = MAH (max allowable headway)
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presence detection passage time (equation)
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PT = MAH - (length veh + length detection zone) / (1.47 * avg approach speed)
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capacity of a lane group
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c = sat flow rate* (eff green / Capacity)
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degree of saturation ( v/c ratio)
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actual flow / capacity
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flow ratio (v/s)
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actual flow / saturation flow rate
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degree of saturation for an intersection
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(v/s) / (g/C) or (actual flow / saturation flow rate) / (eff green / cycle length)
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X = v/c = ?
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= (v/s) / (g/C)
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arrival type (equation)
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AT = 3* P / (g/C) or 3*proportion of vehicles arriving on green / (eff green / Cycle length)
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arrival types 1-6
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progression quality increases from 1 to 6, density increases moving up or down from #3
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relation between flow rate, volume, PHF
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v = V / PHF or flow rate = volume / peak hour factor
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desribe the 4 cases in figure 24.8 (pg 593)
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initial queue? residual queue?
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explain d = d1 + d2 + d3
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avg control delay per veh = avg uniform delay per veh + avg incremental delay per veh + additional delay per veh due to queue
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sneakers equation
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additional eff green used by sneakers = 2*(1+ proportion of veh in left lane) / eff green
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ideal offset
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t(ideal) = length of block / vehicle speed
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simple progression
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all signals set for vehicle released from 1st intersection arrives as green phase begins
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forward progression
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vehicles advancing from simple progression
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flexible progression
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progression coordination changes during the day to meet peak demand direction
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reverse progression
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results when ideal offset is large
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alternate progression
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works for 50:50 splits, uses (C / 2) = (L / S), where L = block length and S = platoon speed... 50% efficiency
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double-alternate progression
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25% efficiency so C = 4L / S
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