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Chapter 4 - Model Details
Pages 32-39

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From page 32...
... • Model 2 was restricted to only more easily obtained data, similar to Model 1B, except that the simpler negative binomial equation form was used. • Model 3 was a simple model (using logistic regression)
From page 33...
... Model Details   33   V2 V3 V1 RTOR LT P1 P2 Figure 14.   Movements at a typical intersection that conflict with RTOR. The equations for the models are as follows.
From page 34...
... 34   Right-Turn-on-Red Site Considerations and Capacity Analysis: Practitioner's Guide For single right-turn lanes, Model 3: exp ;- 2.321 + 3.470 a r C kE q RTOR = R V (7) 1 + exp SS- 2.321 + 3.470 a r C kWW T X For shared right-turn lanes, Model 1A: R V q RTOR = SS- 0.458 + 2.734 a r C k + 0.01406q RWW T X R V S2.670 + 1.438 a r C k - ` 2.870 # 10 -4 j q 1, r - ` 9.837 # 10 -4 j q 2, r W S W S W # exp S- ` 2.733 # 10 -3 j q 3, r - ` 1.939 # 10 -3 j q ped, r + ` 3.692 # 10 -3 j q RW (8)
From page 35...
... S + ` 3.582 # 10 -3 j q R - ` 1.736 # 10 -3 j q ped W T X For dual right-turn lanes, Model 3: R V exp SS- 2.293 + 0.4159d I + 2.851 a r C kWW q RTOR = TR X V (15) 1 + exp SS- 2.293 + 0.4159d I + 2.851 a r C kWW T X where: qRTOR = RTOR flow rate, qR = total right turn flow rate, r/C = red-to-cycle ratio, q1 = total conflicting thru flow rate, q1,r = conflicting thru flow rate during red, qL,r = shadowed left turn flow rate during red, q2 = total opposing left-turn flow rate, q2,r = opposing left-turn flow rate during red, qSL = total shadowed left-turn flow rate, qped = total conflicting pedestrian flow rate, qped,r = conflicting pedestrian flow rate during red, qplped,r = parallel pedestrian flow rate during red, qLT = total shadowed left turn flow rate, δ2L = indicator variable for the presence of two or more right-turn lanes on the approach, δPLCW = indicator variable for the presence of a parallel pedestrian crosswalk, δ1RCL = indicator variable for the presence of one receiving lane, δSLT = indicator variable for the presence of a shadowed left turn, δCBL = indicator variable for the presence of a conflicting bicycle lane, and δI = indicator variable for whether the subject approach is an interchange ramp.
From page 36...
... If a right-turn overlap exists at the intersection, this interval would be part of the green time. If no overlap exists, drivers may turn right and typically do not have conflicting vehicle volumes unless U-turns exist from the shadowed left-turn movement or pedestrian overlaps exist.
From page 37...
... In brief, the RTOR movement is analyzed as a two-way stop-control intersection during this interval. The same procedure is done to calculate the capacity contributed by the unsaturated red time associated with movement V2, cV2, by using the above three equations, substituting values for movement V2 in place of V1.
From page 38...
... To employ the estimated RTOR capacity in a delay estimate for a right-turn movement, the HCM delay equation may not be the appropriate equation form, because it is based on the assumptions of certain traffic behaviors occurring in the red and green intervals, which for a RTOR movement do not follow those behaviors. NCHRP Web-Only Document 368 discusses this in more detail.
From page 39...
... 4.6 Conclusion This chapter provided a description of the equations used for the volume and capacity adjustments contained in the spreadsheet tool. Complete methodological details, including descriptive statistics of dependent variables, other alternative models considered, and model validation are included in NCHRP Web-Only Document 368.


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