Category «QRS II Development»

The Conundrum of NCHRP Report 716

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 …

Convergence Criteria for Equilibrium Traffic Assignments

If you are reading this article you probably know something about equilibrium traffic assignment and how it is done in at least one travel forecasting package.  Traditional methods of equilibrium traffic assignment, say Frank-Wolfe decomposition and MSA (method of successive averages) found in wide use around the world, converge to an equilibrium solution rather slowly. …

Reliability in Path Building

There is an idea floating around the transportation planning community that drivers are sensitive to the variability in travel time when choosing their routes. This idea suggests that drivers will tend to avoid short routes where the travel times are unpredictable and may instead choose longer routes where the travel times are consistent from day …

Parallel Processing and Multithreading

Almost everyone today has a computer with more than 1 core.  Those of us who run time-intensive applications, such as simulations, are frustrated in having to wait for results that should be gotten much sooner had all the cores been fully engaged on the task.  Many of us have had the experience of looking at …