The 2010 Highway Capacity Manual (HCM) procedures may be used to analyze coordinated intersections, but there are some unique settings such as the Platoon Ratio required for accurate results. Chapter 18 in HCM 2010 highlights the procedures related to isolated signalized intersections, while Chapter 17 focuses on the procedures associated with coordinated intersections. The Platoon Ratio describes the quality of progression for a platoon of vehicles arriving on green. As described in HCM 2010, the user should select a Platoon Ratio based on field observations and their knowledge of the corridor.
Table 1: Traffic Flow Along Coordinated Arterials
“Should I use Synchro, SimTraffic, or both?” We often get this question from users. Today’s post discusses the benefits to help clarify the issue.
The “Choosing an Analysis Method” post from two weeks ago discussed the three macroscopic analysis methods available in Synchro: Percentile Method, HCM 2010, and HCM 2000. In addition to these choices, you can use SimTraffic for analysis.
The intention is to use Synchro and SimTraffic as companion models. Synchro can be used to determine macro level LOS and delays, then use SimTraffic to simulate realworld conditions. Not all projects require use of SimTraffic. Synchro analysis may be sufficient for a high-level planning study, for example.
Not an expert at signal phasing? No problem! Even if you are, using Phase Templates is a great shortcut. The default phase templates are also NEMA compliant. You may remember from last week’s post that the HCM 2010 requires NEMA phasing. Phase Templates are a quick way to set the phasing in preperation for an HCM 2010 analysis.
It is common to assign the main street through movements as phases 2 and 6, so the Phase Templates are setup in this manner. For example, selecting the East-West template will set the eastbound through as phase 2 and the westbound through as phase 6. Here is a diagram of the Synchro default Phase Templates:
In Synchro, there are 3 methods for reporting signalized intersection delays. This includes:
Each of these methods are macroscopic models, which use equations to determine measures of effectiveness such as delay and queue length. Synchro’s companion model, SimTraffic, is a microscopic simulation model. Microsopic models, like SimTraffic, simulate the movement of individual vehicles. Operational measures of effectiveness are collected on every vehicle and can be summarized in a report. Here I will focus on the 3 macroscopic models listed above and save the comparison between Synchro and SimTraffic for another post.