As described in the lead article, we at TModel Corporation have been hard at work on several fronts. Level of Service (LOS) is often used as a decision point in transportation planning. Any tool that can facilitate the evaluation of LOS and allow comparison between different alternatives is beneficial.

The new LOS module (section 1.7.5) was shipped with the most recent TMODEL2 update and is available on the BBS. LOS is defined for 20 categories of facilities including Freeways, Ramps, Multi-Lane Highways, and Arterial Streets. The new module allows you to also designate categories that permit automatic selection of the facility based upon speed or number of directional lanes. For example, you may designate all freeways as category 1, then during analysis the 2 lane segments with coded speeds of 70 or above will be analyzed with the category 2 criteria. The categories, facility type descriptions and the criteria from the 1994 HCM are shown in the table above.

Once the category designations are setup according to your model structure, you can use the same criteria for each alternative you analyze. The analysis value and the color are coded into the SZ1 and SZ2 fields of the link file. After the analysis is performed, menu options allow you to save the link file containing the results of the link file analysis as well as the display attributes file (.DAF) that will allow quick and easy plotting of your results.

You have two ways to analyze your data, either on a link by link basis or by segments that may include several links. In order to average the results over several links, all of the links must be in a contiguous segment and all of the links must be given a unique Area designation. Link Area is easily assigned for groups of links using the Buffer command in the Network Graphic Editor. It is crucial that the link segments be contiguous for the LOS computation. It is recommended that check plots be created if you are using this feature.

One other helpful tool included in the LOS module is the ability to rapidly create Display Attribute Files (.DAF) for any of the link attributes. You may select any of the standard attributes to display. Colors will be automatically assigned using the number of colors and the starting color that you specify. Colors will be sequentially assigned for each attribute value up to the number of colors and then the sequence will repeat. Colors are assigned for each changeof 100 units of capacity and length and for each change of 5 units for speed.

This module has been released as a Beta module, and we are planning on adding more features to it in the future. We welcome and appreciate your comments.