Problem 4: Clifton Country Road

Problem 4 Printable Version

The intersection of Clifton Country Road and Route 146 (Intersection D) is the most complex, busiest, largest, and most complex in the network. Exhibit 2-36 shows an aerial photograph of the site. (North is toward the top.)

The main question at this intersection will be: are geometric changes and/or adjustments in signal timing needed to accommodate the site-generated traffic? Since a lot of the site-generated traffic will be going to and from I-87, the signal timings will have to change, dictated by the actuated controller. But geometric changes might be needed as well. In the process of answering these questions, we can use this intersection to illustrate a number of analysis issues.

As you can see in Exhibit 2-37, the intersection’s eastbound approach is five lanes wide (left, triple through, and signalized right). The westbound approach is also five lanes wide (double left, double through, and free right). The southbound approach has three lanes (left, left/through, and right/through) while the northbound approach has four (double left, through, and free right). The eastbound left-turn bay is about 150 feet long. The westbound left-turn bay is about 400 feet long so it can accommodate heavy volumes coming from I-87. On the southbound approach, there’s space to store about 10 cars per lane to the upstream intersection with Old Route 146. On the northbound approach, about 20 cars can be stored per lane prior to the first side road intersection.