Sub-problem 4b: Clifton Country Road PM peak hour - Existing Conditions

Right Turns on Red
In all of the datasets for the Clifton Country Road intersection we assumed there are a substantial right turns on red (RTOR) for the eastbound, westbound, and northbound approaches. (click here to open any one of the datasets.) Each of these three approaches has an auxiliary right turn lane. The one difference among them is that the eastbound right-turn lane is quite short and the right turn on red is often difficult to make because the lane is blocked, the westbound lefts are turning, or the southbound throughs are in motion.

Exhibit 2-44 shows you the difference in predicted performance between the base case PM Existing condition and a more conservative condition involving downward adjustments to the RTOR values. Follow the link to see Dataset 38 (2002 PM base case) or Dataset 39 (downward adjusted RTOR) datasets. Compared with Exhibit 2-43, three columns show the RTOR values being employed for the eastbound, westbound, and northbound approaches. For the eastbound approach we assume 10% of the right turning vehicles turn on red. For the westbound approach we assume all of them turn on red since there is a separate right-turn auxiliary lane and there’s not much opposing traffic. (There is never a queue in that lane.) For the northbound approach we assume as many vehicles turn right during phases 1 and 2 as westbound lefts in a single lane (550/2). We also assume that 10% of the total northbound rights turn right during other times when the light is red northbound. (550/2+0.1*508 = 326).

  to Sub-problem 4c