CEEn 662
Lab #4
Using Synchro and SimTraffic
For simulating freeway and ramp junctions
According to Trafficware, SimTraffic does not simulate ramp metering (See page 23-1 of the Synchro Studio 9 User Guide, which states “SimTraffic will not
model ramp metering, bus stops, bus routes, bus and carpool lanes, light rail, on-street parking, and short-term events.”). Hence we later use CORSIM (TSIS) in
this class to simulate freeways with ramp metering. This lab is intended for you to get used to freeway simulation using Synchro Studio. We try to model a ramp
area that does not have ramp metering.
Today, we create a freeway section with two onramps as shown in page 232 of May’s book, 8.2.1 Base Conditions using Synchro Studio to get a feel of freeway
simulation. Basically I want you to see queue forming on a freeway segment that has a demand greater than the capacity of the facility—something like the one
you see in Figure 8.8 on page 236. Note that the analysis done in Chapter 8 is a static analysis; hence what you see in the simulation may be quite different from
this one. Pay attention where you see queues. Create a network shown in Figure 8.4 (b) using Synchro. First, use the demand values for time slice 1 in Figure
8.4(b) then the demand values for time slice 2.
Today we will simply use one-interval simulation; so you need to simulate time slice 1 first, then change the demand values, and simulate time slice 2. To do
multi-time period analysis, you need to create a UTDF (Universal Traffic Data Format) file outside Synchro Studio for each extra interval you need. CORSIM
allows you to create a multi-period analysis file within CORSIM and do a multi-period by simply selecting a multi-period analysis. In that sense, CORSIM is
superior to SimTraffic but the SimTraffic’s output presentation is much better than CORSIM. Synchro is the main tool of this software (signal optimization) and
SimTraffic is meant to give the user a simple simulation analysis and animation that will help the user review the correctness of his or her input data and prepare
a 3D animation for clients to understand what may happen with the cases you have analyzed.
Read pages 5-9 and 5-10 of the Synchro Studio 9 User Guide to learn how to make freeway links. First, follow exactly what the instructions on pages 5-9 and 510 to learn how to use “bend node” to create the acceleration lane. SimTraffic gather MOE statistics on bend nodes also; make sure you click the Bend node
statistics in the Select Report(s) window after selecting the Create report option (Beware that Synchro does not analyze bend nodes because they are not
intersections.). Read a paragraph about the Headway Factor (Also, use the Find command to search through the Synchro Studio 9 User Guide for the Headway
Factor). Sample screenshots of Synchro and SimTraffic models are shown in the following pages.
This exercise will help you understand better the concept presented in Chapter 8 of May’s textbook later on.
Report of Lab #4: Summarize MOE’s of each freeway link for time slice 1 and 2 from SimTraffic and comment (Make sure you make 5 15-min runs of each
case. Usually 10 runs are recommended but 10 runs will quickly fill up your account.) Maximum three single-spaced pages. Tables and figures are part of this
page limit.
Bend node
Ramp node as a regular
intersection
Ramp node as a regular
intersection
Bend node
Sample of Time Slice 1
Sample of Time Slice 2