Introduction to the Four Step Travel Demand Model
The center of most travel demand models is the "Four Step Model". This model was created in the 1950s to determine the demand on roadways. The four steps include: Trip Generation Trip Distribution...
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Travel Demand Modeling 101 Part 1: Terminology
It occurred to me that many people likely do not understand all of the terminology of travel demand models. Because of this, I felt the need to list many of them here. Assignment: A process that...
View ArticleCube Voyager Speed Clinic
There are several issues with long travel demand model run times. Deep down, these are supposed to be planning tools, and taking too long for results can reduce the practicality of using a travel...
View ArticleCube Voyager: Using Cluster with DBI
Credit for this goes to Citilabs Support, although I made some adaptations. In Matrix when using DBI, PAR ZONES=1 will effectively shut off Cluster. Therefore, the following works really well....
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Using a C++ DLL in Cube
One thing that can drastically speed Cube is using a DLL to do big tasks, like Nested Logit Mode Choice. However, doing this can be fraught with hair-pulling errors. This post shows some techniques to...
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Trip Rates: Averages and Analysis of Variance
This is second in the R in Transportation Modeling Series of posts. I've been going between R, R Graphics Cookbook, NCHRP Report 716, and several other tasks, and finally got a chance to get back on...
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Cube Voyager XCHOICE: The Missing Help Doc
First note: I sent this to the support people at Citilabs recently, so maybe on the next update they'll include this in the help document, as I think it is sorely missing. Or maybe I'm just crazy (you...
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Logsum Issues
I've been working through distribution in the model, and I was having a little bit of trouble. As I looked into things, I found one place where QC is necessary to verify that things are working right....
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