Laserfiche WebLink
Dowling Associates, Inc. <br />Transportation Engineering Planning Research Education <br />Road Type Validation <br />The standard Federal Highway Administration and Caltrans travel forecasting guidelines recommend <br />validation criteria based on a comparison of total model volumes and traffic counts on various facility types: <br />Freeways: 7% <br />Highways: 10% <br />Arterials: 15% <br />Collectors: 25% <br />Peak Factor Adjustments <br />Dowling Associates would propose to use a peak factor adjustment process. The peak factor adjustment <br />process adjusts the peak hour percentages of daily traffic for specific zonal interchanges based on peak hour <br />congestion levels. <br />Fitting Validation to Traffic Counts <br />In recent years, many travel demand modelers have implemented procedures where the base year trip matrix <br />is factored to better replicate observed traffic counts. This is referred to by various names such as "matrix <br />estimation" or "difference method." Dowling has implemented these procedures for the current Pleasanton <br />models and tested them on several other models. <br />Dynamic Validation <br />The validation criteria above indicate the model's ability to replicate base year observed traffic. Dynamic <br />validation tests the ability of the model to provide reasonable forecasts. For this test, a small and large <br />residential development and a small and large commercial development will be added to the model. We will <br />then report the changes in traffic resulting from the new development and ensure that the increases are <br />appropriate. <br />1.7 CREATE LINK BETWEEN TRAVEL DEMAND AND SIMULATION MODELS <br />As part of the 2006 Model Update and <br />Baseline Analyses, Dowling Associates <br />created a link between the travel demand <br />model nodes and the Synchro Study <br />Intersections. This included identification <br />of the nodes to the north /south /east /west. <br />Thus intersection turn volumes (12 <br />movements) can be summed to <br />approach /departure (app /dep) volumes and <br />uploaded onto the Cube network for model <br />validation. Alternately, with the nodal <br />identification in place, forecast volumes <br />from the travel demand model can be <br />uploaded into Excel and then brought into <br />Synchro. <br />City of Pleasanton <br />2009 Traffic Model Update May 13, 2009 <br />