[CTPP] sub-area analysis

Hi, everyone - I am working on a sub-area analysis and ran into some problems. I wonder if you happen to have similar experiences and would share your suggestions/comments. Our travel forecast model covers more than 50 towns in our region and has 1174 TAZs. The sub-area analysis focuses on an area of 2 towns. The current 25 traffic analysis zones in these 2 towns will be expanded to 67 zones for a more sensitive highway alternative analysis. The total number of model zones will increase from 1174 to 1216. The sub-area analysis is in the traffic assignment step only. The plan is to borrow the trip matrices from the first 3 steps of the model and to expand the trip matrices from 1174*1174 to 1216*1216, so that the matrices can be used in traffic assignment. A highway layer with the expanded zone system is available. It has 1216 centroids. A network will be created which has the following link attributes: Link id, Link direction, Link mode, Link speed and capacity, Link free flow time, and Alpha and beta value for the BPR equation. Traffic assignment will be run from the tool menu using: The network *.net (1216 zones) The highway layer (1216 zones) The trip matrix (1216*1216) The link traffic volumes generated from this assignment step is very different compared to the original model link volumes. I wonder if the additional centroid connectors in the highway network caused this problem. Any thoughts? Your input will be appreciated. Hua Tan Transportation Engineer Capitol Region Council of Governments 241 Main Street Hartford, CT 06106 Phone: 860-522-2217 * 21 Fax: 860-724-1274 www.crcog.org