Turning Speed

Adding to our series about SimTraffic calibration, today's post focuses on the Turning Speed. Turning Speed is a simple item to code, but it can make a noticeable difference when modeling intersections with large turning radii or freeway ramps. This setting is a great place to start calibrating your SimTraffic model.

Make sure to read rest of the series; we have discussed Link OD Volumes, Lane Alignment, and the Positioning & Mandatory Distances.

We will be focusing on the westbound right turn of the intersection shown below. As you can see, it is a free-flowing channelized right-turn. With this type of geometry, drivers typically turn right at speeds approximately 5 to 8 mph higher than a typical non-channelized right turn (NCHRP 208).

By default, the Turning Speed is 15 mph for left turns and 9 mph for right-turns. As you can see in the image below, the Turning Speed for the westbound right-turn has been increased to 15 mph. This change will be visible the SimTraffic animation, but it will also impact the results such as delay and queue length.

Below you can see the SimTraffic Queuing Report before and after the Turning Speed was increased. Notice how the queue lengths for the westbound right-turn decrease after the Turning Speed is increased.

If you would like a refresher on the various reports available in SimTraffic and some best practices to keep in mind when creating them, please refer to the Just-In-Time Training video "SimTraffic: Creating Reports". JIT videos are available with your Synchro 9 Support package, and can be accessed through the Help menu in Synchro.

Happy calibrating!