A number of agencies consider the development and maintenance of a multi-year master network an efficient method for developing, storing, managing, updating and accessing the entirety of network related data. A multi-year master network file typically includes a base year network and all future year network alternatives.
E-mail List respondents noted similar means of developing and maintaining multi-year master networks. The general basic steps employed by respondents to develop a master network are as follows:
The extraction of a single year network from the master network for model application purposes is accomplished through the use of a selection flag or filter to select the relevant links and attributes required for a specific model year application. One respondent noted that their process includes coding an initial year attribute to designate the year that the facility is operational. Likewise, a delete year attribute is used to disregard links that will no longer exist in a future year network. Upgrade and final year attributes account for network enhancements that occur in interim or final year networks.
One noteworthy observation was the importance of having a means of checking extracted networks for internal consistency. Once an alternative or year specific network has been extracted, it is important to have an automated process perform a sequence of tests to ascertain the integrity of the network.
E-mail List respondents noted a number of benefits in maintaining a master multi-year network; these included the following:
The task of creating and maintaining multiple networks appears to be more manageable within a multi-year master network process; a process that has been facilitated with the advent of GIS integrated modeling platforms. Individual year application is a straight forward process; year specific networks can be built by a simple query process. As noted, numerous benefits are derived from maintaining a master network, perhaps none more so than the reduction of network coding time, and the added accuracy and internal consistency among networks. This is especially relevant for large urban area networks that may include numerous alternatives and proposed improvements.
The objective of the series is to provide technical syntheses of current discussion topics generating significant interest on the TMIP e-mail list. Each synthesis is drawn from e-mails posted to the TMIP email list regarding a specific topic. The syntheses are intended to capture and organize worthwhile thoughts and discussions into one concise document. They do not represent the opinions of FHWA and do not constitute an endorsement, recommendation or specification by FHWA. These syntheses do not determine or advocate a policy decision/directive or make specific recommendations regarding future research initiatives. The syntheses are based solely on comments posted to the e-mail list.