Information about the travel forecasting package, Quick Response System II
It could be argued that every technical field has its barriers to innovation, but barriers are particularly acute in travel forecasting. If photography innovations were adopted at the same rate as ours, many of us would still be using Instamatics. A good friend of mine recently described the regional model in his locality “the best …
I just recently declined to referee a paper from a journal because the authors so infuriated me by the second paragraph that I decided I could not be objective. Thus, the reason for this blog article. Another TRB paper evaluation season has come and gone. Some authors are delighted to have gotten into the Annual …
QRS II had always had a form of feedback to trip distribution (more correctly to trip generation, although the trip generation step was insensitive to network travel times). In 1988 or so when I was testing a new installation of a “modified” Evans’ algorithm I had put into QRS II, which was quite similar to …
It is not so much that the recent report for FTA “Traffic Assignment and Feedback” is wrong. (I will call it the TAF report from here on.) The TAF report is just not sufficiently prescriptive. It is absolutely clear from the TAF report that traffic assignments, as practiced by many large MPOs, are ill; but …
Balancing of traffic counts is an attempt to eliminate errors due to lack of conservation of vehicles through intersections and interchanges. My friends at the WisDOT swear by it. Most other traffic and travel modelers have never heard of it. One of my co-authors on NCHRP Report 765, Tom Creasey, was charged with writing up …
OD table estimation from traffic counts only makes sense if it is viewed as a method of statistical inference. Any other interpretation of OD table estimation causes splitting headaches. Now that we agree on this fact, we must also face the realization that there is a lot of junk masquerading as good technique. Short of …
It seems that empiricism in the absence of theory is the enemy of transferability. Physicists have postulated that the speed of light in a vacuum is a constant; no matter (not a pun) where or when it is measured, it is always the same. The speed of light is perfectly transferable. However, in travel forecasting …
At some point in the process of performing the contract that led to NCHRP Report 716 its authors (or maybe its project panel) deviated from what many of us thought the contract was all about. Personally (I will not involve a bunch of anonymous confidants), I was expecting NCHRP Report 716 to be an update …
The RADIUS models were originated by John Shaw, once of WisDOT and now working for the TOPS Lab at the University of Wisconsin—Madison. He envisioned using QRS II as a dynamic traffic assignment engine for a group of models for analyzing work zone traffic diversions. Part of the concept was synthetic OD table estimation from …
Estimating origin-destination (OD) tables from ground counts can be controversial. In many cases the number of variables of the estimation problem greatly exceeds the number of data points. This means that additional information must be gotten from somewhere, and the quality of that information is often suspect. QRS II contains many different methods for performing …