Traffic model, CIP on tap Monday

By From page B1 | February 24, 2014

Policy wonks will have a full plate Monday when the El Dorado County Board of Supervisors holds a special meeting to discuss, growth, traffic and road maintenance. The new Travel Demand Model will be officially unveiled and explained by the county’s Long-Range Planning Division staff. A TDM, as it’s called, is a collection of data gathered over several years using several methodologies. The model shows real and anticipated patterns of travel throughout the county projected over the next 20 years and is primarily based on projections of residential development and population growth.

“TDMs are used to forecast future trips on transportation facilities (e.g., roadways) and predict a transportation system’s performance on roadways as a result of vehicular, transit, bicycle and pedestrian traffic” the agenda summary reads. “TDMs provide an objective look at the transportation system, and help policy-makers, planners, engineers and other stakeholders make informed transportation investment decisions. TDMs are one of many tools used by El Dorado County and others to generate information that helps inform the board in the decision-making process.”

The documents further note that: “Since the 1950s when they were first developed, TDMs have become sophisticated analytical tools used at all levels of government, by educational and research organizations, and by the private sector. Modern TDMs are capable of:

• Showing effects of road improvements (i.e., road widening, etc.), the addition of new roads, and intersection and interchange improvements on traffic patterns and overall transportation system performance.

• Showing impacts of proposed land development projects.

• Forecasting roadway volumes.

• Estimating traffic patterns and impacts based on alternative land-use plans.

• Providing inputs for micro simulation analysis which can show individual vehicle movements at intersections and roadway segments.

* Providing inputs for California Environmental Quality Act (CEQA) analysis, such as air quality and noise impacts resulting from traffic.”

The county’s TDM, developed in 1998, has become significantly “dated.” Software is no longer available and the system is incapable of operating numerous more modern applications, according to the agenda packet. Similar models are currently in use by Caltrans and the Sacramento Area Council of Governments (SACOG), albeit for somewhat different purposes. SACOG is responsible for creating a regional transportation plan and prepares a Regional Housing Needs Assessment which is also used in the county’s travel model.

Responding to residents’ concerns regarding several proposed large housing developments that could require amendments to the county’s General Plan, planning staff clarify that the TDM includes “only existing  General Plan land-use designations were used as the basis for the TDM. No proposed development projects were included.”

Two other items round out the Feb. 24 special meeting. Information on the county’s Capital Improvement Program and Traffic Impact Mitigation (TIM Fee) program will be updated. Also, information on how the county implements its General Plan policies regarding traffic issues  — Measure Y — will be discussed.


Chris Daley

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