The most recent update implemented some very important changes to the Link and Node Delay Coefficients (formerly called Parameters) files. As you know, we at TModel Corporation are very committed to the premise that you should use realistic, rational values for speed and capacity. That is why we believe accurate node modeling to be so important.

Following the article on node delay parameters, some of our users had suggested changing the node and link delay parameters files to better model the delays that occur as the Volume to Capacity Ratio increases. We have been bothered for some time that the delays really didn't start to show up in the equations until the V/C ratio was close to or greater than one. In some cases, this led to some skewing of capacities so that the delays would be more representative. However, when the capacities have been adjusted, then any comparisons you make using the Network graphics are also skewed.

The July update of TMODEL2 implements new delay formulations that allow the delay curve to be offset with a constant. The new constant provides more realistic representations of the delay. There is also the option of "breaking" the equation at a specified upper limit. That is, you can use one set of coefficients below a V/C ratio of .95 and another set above .95. Using this option, you can have more control over limiting the assignment of volumes when the V/C ratio is greater than 1.0. The new formulation seems to improve every model on which we have tested it. Your previous delay parameters can be imported and still used, if you wish, without implementing the constant and second set of coefficients, but you will be missing out on a powerful way to add more realism to your model. Make sure and read the documentation that came with your update. Important information!