STEP 1. DEFINE THE PROBLEM

This first step consists of defining the problem to be studied, identifying the critical intersections to be analyzed and gathering the necessary input data.

Figure 51 Study Area

The problem is to analyze the traffic impacts of the proposed 53 single family dwelling unit Rancho Verde development in Carmel Valley, California. This development also includes 5,000 square feet of local commercial development.

A preliminary engineering inspection of the area has identified 5 critical intersections (see Figure 51) where it is desired to compute the level of service impacts of the project.

There is another approved development, Pecos Steel, (expected to employ 100 people) currently under construction, whose traffic should be included in the cumulative analysis.

The TRAFFIX network (shown in Figure 52) is determined by:

Selecting those critical intersections likely to be impacted by the proposed project and for which a level of service analysis and traffic forecasts are desired.

Identifying gateways for traffic entering/leaving study area.

Identifying zones where land development will generate new traffic. Zones are generally individual development projects but may include multi-use projects and multiple developments. Multiple developments with identical trip distribution percentages and paths to the gates may be combined into the same (single) zone. The impact fee analysis will treat the developments in the zone as a single unit.

Figure 52 Coded TRAFFIX Network

The data needed for a typical traffic impact analysis include:

The amounts and types of land uses for the new developments;

The appropriate trip generation rates and the percent of trips from each development going to each gate;

Intersection lane geometry, signal timing, and turning movement traffic volumes.

For this tutorial we will input the data for only one intersection and one zone. The necessary data are listed in Tables 12, 13 and 14. Users interested in seeing how the entire problem is coded and in checking their work should look at the “Sample.TFX” database using TRAFFIX for Windows.

Table 21 Trip Generation Data

Table 22 Trip Generation Data