Choosing an Analysis Method

In Synchro, there are 3 methods for reporting signalized intersection delays. This includes:

• Synchro Control Delay (Percentile Method)
• HCM 2000
• HCM 2010 (new in Version 8)

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.

To make an educated choice on which method is the best to use in each situation, you should familiarize yourself with the each of these methodologies and their limitations. Here is some information to get you started.

The basic premise of Synchro’s Percentile Method is that traffic arrivals will vary according to a Poisson distribution. Vehicle delays are calculated for the 90th, 70th, 50th, 30th, and 10th percentile scenarios, and reported using a weighted average.

The results displayed in the Timing and Phasing windows and the “Int:” reports are based on the Percentile Method. The HCM 2010 data is displayed in the HCM 2010 window. The HCM 2000 and HCM 2010 results can also be found in their respective reports.

All macroscpic models have limitations. The table below summarizes the limitations of methodologies available in Synchro.

Additionally, the HCM 2010 requires strict adherence to standard dual ring NEMA phasing. Phase overlaps and other non-compliant phasing sequences cannot be analyzed using this method.