Problem 6: Planning Level Analysis 

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Thus far, we have taken an operational perspective in our analysis. Occasionally, when we are considering future conditions, we are better served by looking at a less detailed level of analysis, often called a planning level analysis. Let's take this planning perspective now, considering the twenty-year traffic projections. All of the intersections on U.S. 95 will be examined to assess their sufficiency at the end of the twenty-year period. The signalized intersection quick estimation procedures contained in Appendix A to Chapter 10 of the HCM 2000 will be applied for this purpose.

The question to consider now is whether or not the number of lanes at the U.S. 95/Styner-Lauder Avenue intersection will be sufficient to accommodate the projected traffic demand over the twenty-year planning horizon. A uniform increase of two-percent per year will be applied to the current volumes on all traffic movements. Compounded annually, the two-percent annual increase will produce a growth factor of 48.6% to apply to the current volumes.

The quick estimation method covers all aspects of signalized intersection analysis, including determination of left-turn treatments, lane-volume computations, estimation of signal timing plans, calculation of the critical v/c ratio, and calculation of average control delay. The delay calculations use the same mathematical procedures as the operational analysis method, except that certain details, such as pedestrian minimum times, are excluded from consideration. Liberal use is made of assumptions and approximations.

This method is well suited to analysis of conditions projected over the long term where the accuracy of the traffic volumes is questionable and immediate implementation of results is not an issue. The method will be applied to each of the intersections on U.S. 95 in separate sub-problems:

Sub-problem 6a: Planning Analysis at Palouse River Drive

Sub-problem 6b: Planning Analysis at Styner-Lauder Avenue

Sub-problem 6c: Planning Analysis at Sweet Avenue

Sub-problem 6d: Planning Analysis at SH-8