CAO Request Board Provide Direction on the Roadway Network and Traffic Analysis Zone Maps
A travel demand model uses computer software to simulate travel patterns and existing demand conditions. Model scenarios for future years are used to help guide policy and funding decisions such as construction of new roadways and land use decisions. The El Dorado County Department of Transportation (DOT) uses the travel demand model to determine its Capital Improvement Program (CIP) and the required Traffic Impact Mitigation (TIM) Fees.CAO, EDC, July 20, 2012
A travel demand model uses computer software to simulate travel patterns and existing demand conditions. Model scenarios for future years are used to help guide policy and funding decisions such as construction of new roadways and land use decisions. The El Dorado County Department of Transportation (DOT) uses the travel demand model to determine its Capital Improvement Program (CIP) and the required Traffic Impact Mitigation (TIM) Fees.
The data inputs required to develop a regional travel demand model include the roadway network and socioeconomic data such as housing and employment for the county. The data is tabulated and entered into the software package using a Traffic Analysis Zone (TAZ).
History: In the early 1990’s DOT developed a travel demand model in support of the County’s General Plan and its accompanying Environmental Impact Report (EIR). The initial TAZ’s were based on census data blocks and were nested within the Sacramento Area Council of Governments as well as Caltrans TAZ structures. The existing conditions socioeconomic data was based on information from the Planning and Building Departments. The land use projections for the 2010 and Build Out planning horizons were developed by Economic and Planning Systems, Inc. (EPS) using estimated average development densities across market areas and was not capacity constrained.
This model was used to generate traffic volume forecasts so that future roadway deficiencies resulting from implementation of the County’s General Plan could be determined and mitigated. The required TIM fee program and the accompanying CIP were developed using the El Dorado County Travel Demand model. The use of the model for development-specific traffic analysis highlighted the need for additional work on the land use projections as using estimated average development densities, in some instances, did not reflect the actual conditions.
In 1998, as part of continued planning efforts to address transportation infrastructure needs, DOT started a major update of the County-wide travel demand forecasting model. The update of the model was conducted under the oversight of a peer review panel consisting of representatives from Caltrans District 3, El Dorado County Transportation Commission and the Sacramento Area Council of Governments. A peak hour component was added to the model during this update.
Measure Y was passed in late 1998 and in February 1999 the Superior Court ruled that the County had failed to comply with the California Environmental Quality Act (CEQA) in the adoption of the 1996 General Plan. The certification of the General Plan EIR and the adoption of the General Plan were set aside. In response to the judgment and the Writ of Mandate, the County began the process of adopting a new General Plan and conducting a full environmental review pursuant to CEQA. Updating the General Plan necessitated updating the TIM fee program and CIP. EPS was hired to update the land use forecasts with consideration of the Writ and Measure Y for 2025 and Build Out planning horizons.
In 2004, the five year review of the County’s General Plan began, and the Board of Supervisors (Board) directed DOT staff to begin a process to revise and update the County’s Road Development Fee Program. A Citizen Advisory Committee (CAC), which became the TIM Fee Working Group (TFWG), was formed to work with DOT to explore different development fee options. At this time both a 10 year and 20 year program were developed. The socioeconomic data previously generated by EPS for the travel demand model was evaluated and determined as still valid therefore travel demand model was not given a major update at this time. Additional programmatic analyses occurred and resulted in an updated TIM fee program that was adopted in August 2006. This version of the travel demand model is still being used for development-specific traffic impact analyses. In 2010, an effort to update the travel demand model was started, as new software technologies highlighted the limitations of the existing travel demand model. This effort included an attempt by the TFWG to redraw the TAZ boundaries; however the draft map was created but was not formally approved.
On December 19, 2011, the Board received a Travel Demand Model Needs Assessment. The assessment highlighted areas where the existing model could be improved. On January 24, 2012, the Board authorized the update of the Travel Demand Model (TDM) through a contract with a traffic consulting firm, Kimley-Horn and Associates, Inc. (KHA).
The new TDM will use a software platform known as CUBE which will maximize the use of the County’s Geographical Information System (GIS) and allow DOT to house and maintain the new updated model. The updated model will be a macro regional model for El Dorado County and will allow county staff to efficiently evaluate the potential impacts of any proposed development. It is the intent of staff to provide the model scenarios to outside consultants for use in their preparation of project specific analyses, thus ensuring consistent projections for input to their studies. The update of the TDM will also allow El Dorado County Transportation Commission (EDCTC) the opportunity to use a local regional model for their studies and preparation of the Regional Transportation Plan and Regional Transportation Improvement Plan. Consultation and coordination with the EDCTC will ensure compliance with all the applicable state requirements. As requested, each step in the update process is being presented to the Board for their information and approval.
On April 16, 2012, KHA presented the Draft Land Use Assumptions for the Travel Demand Model to the Board, as the first component of the TDM update. On May 1, 2012 the Board approved the assumptions for determining the projections for a new 2035 planning horizon.
On June 26, 2012, the Board received Technical Memorandum #3: Revised Roadway Network and Technical Memorandum #4: TAZ (Traffic Analysis Zone) Development and Considerations for review and comment.
The Technical Memorandums #3 and #4 were distributed to the TIM Fee Working Group (TFWG) and the Engineering Subcommittee of the Economic Development and Advisory Committee (EDAC) for review and comment on June 14, 2012. A workshop for these groups was held on June 27, 2012. A public informational workshop on the Travel Demand Model was held on June 28, 2012. The Power Point presentations from the workshops are posted on the Land Use Policy Programmatic Update (LUPPU) website. The Technical Memorandums #3 and #4 have also been supplied to El Dorado County Transportation Commission, Caltrans, and the Sacramento Area Council of Governments for review and comment.
The previous workshops provided an introduction to Travel Demand Modeling and covered the following topics: · Why update the travel demand model? · What is a travel demand model? · Micro vs. Macro models · Four Step Process · What the model can and cannot do
Additional topics included discussions on the Land Use Forecasting using examples from the Board presentations on April 16, 2012 and May 1, 2012. Staff requested comments on the documents be submitted to DOT by early July to ensure inclusion in the information provided to the Board at the July 24th meeting.
Reason for Recommendation: Staff is requesting the Board of Supervisors provide comment and direction on the summary of network changes of the Roadway Map as discussed in Technical Memo #3 (Attachment 3A) and the development and considerations of the TAZ Map update as discussed in Technical Memo #4 (Attachment 3B). The Roadway Network Map, included as Figure 4 in Attachment 3A was developed by including base year and future networks for the updated Travel Demand Model. A revision to the Roadway Network was required for use of the updated TDM.
The roadway network provides multiple uses which include serving as the: · Basis for estimating travel time between TAZ’s · Basis for traffic assignments · Tool to facilitate an understanding of how trips are distributed; and · Tool for displaying the level of traffic congestion associated with different land use scenarios.
The Traffic Analysis Zones are an essential part of the TDM that serves multiple purposes, including: · Providing the basic unit for converting spatial area data into tabular data for use by the TDM · Managing interactions between internal land uses, · Channeling trip loading onto the model roadway network, and · Displaying information related to land use, employment, population, socio-economic, and other data.
Finalizing Technical Memos #3 and #4 is critical for the continued update of the Travel Demand Model. It should be noted that minor changes to either memorandum may be needed during the validation and calibration portion of the model update process. Any changes made will be noted in future Board items.
Next Steps: · Consultant to revise Technical Memorandum #3: Revised Roadway Network for El Dorado County Travel Demand Model Update based on direction from the Board of Supervisors at the July 24, 2012 hearing · Consultant to revise Technical Memorandum #4: TAZ Development and Considerations for El Dorado County Travel Demand Model based on direction from the Board of Supervisors at the July 24, 2012 hearing · Staff to return to Board next month for update on Travel Demand Model. Action to be taken following Board approval: Staff to incorporate Board direction into project efforts.
Contact: Kim Kerr, Assistant Chief Administrative Officer