The Cedar St. number
nobody calculated

In the central case — 9 PM demand, 750 veh/hr junction throughput, 1.74 vehicles per household, gate open — median clearance is 26.13 minutes and the slower one run in ten is 31.82 minutes. Across every condition tested, the median ranges from about 16 to 33 minutes. That is the local Cedar number alone, before anyone reaches North Ventura Avenue.

The central case leaves 93 project vehicles waiting at Cedar/Alabama. At 25 ft per stopped car, that is 2,325 ft of traffic. Only 142 ft of Cedar — about five car lengths — lies between the project boundary and Alabama. As a contiguous single-lane queue, the remaining 2,183 ft would have to stand on the project’s internal streets, the same streets fire apparatus would need.

Even the most project-favorable assumption tested — moving every existing neighborhood vehicle below Alabama, even though that overstates the relief — still leaves 47 vehicles, about 1,175 ft.

Moving Cedar junction throughput from 950 to 600 veh/hr moves median clearance at 9 PM from 20.68 to 32.64 minutes; overnight, from 21.14 to 33.39. No field measurement or capacity analysis of Cedar under evacuation demand appears anywhere in the record. The largest uncertainty is not Monte Carlo sampling error — it is this physical input, and how many existing vehicles use each Cedar segment.

Appendix I credits School Canyon with 20% of project traffic. If the gate isn’t open when those residents are ready to leave and they redirect onto the other published routes, more of the project enters Cedar: a 15-minute delay puts all 291 vehicles on Cedar and pushes median clearance to 30.64 minutes (P90 37.22). The record should say who or what opens the gate, and how long after an evacuation order civilians can actually use it.

With the gate open, only 80% of project demand enters Cedar and only 60% continues south of Alabama — at 9 PM, 233 and 175 vehicles. But School Canyon, Willett and Seneca all feed the same southbound North Ventura system. Appendix I’s own unmanaged “Worst Case Scenario” south of Seneca already runs over four hours:

The local and regional questions should stay distinct — but linked. School Canyon and Willett reduce the number of project vehicles on Cedar. They do not create a new regional arterial.

Appendix I page 30 defines capacity as C = N × s × g, and Exhibits 20–21 show 1,700 vphpl (1 lane), a 37.16% green-time value and an adjusted capacity of 631.653 veh/hr. But 0.14 ÷ 0.371 is about 37.7%, not 37.16% — possibly unrounded V/C values. The consultant should identify them, the number of southbound lanes, and the basis for the effective-green figure.

Appendix I also disagrees with itself at 9 PM: the page 33 narrative states an 18-minute project increment north of Seneca, while Exhibit 21 shows about 99 minutes without the project and 110 with it, and Exhibit 22 reports +11 minutes. And the overnight period, when project demand peaks at 303 vehicles, was never analyzed at all.

This is a screening model prepared by a resident, not a certified traffic or evacuation study. It is a Monte Carlo queueing model of the local Cedar corridor — not a traffic microsimulation — built to test whether local clearance is materially sensitive to reasonable changes in demand, junction service and gate timing.

• The 47-household count is resident-mapped; there is no verified household-by-junction route map.
• The 600–950 veh/hr values are sensitivity rates, not measured capacities of the Cedar intersections.
• The 2.00 vehicles-per-household case rests on a small, self-selected neighborhood sample.
• No capacity penalties are applied for smoke, fire apparatus counterflow, disabled vehicles, collisions, trailers, pedestrians or emergency lane closures.
• Willett is treated as unconstrained after Alabama, and School Canyon as unconstrained after the gate — both favor shorter clearance.
• The model does not reproduce the full Zone 1 + Zone 4 network; North Ventura figures on this page come from Appendix I.

These limits are why this model should not be used to declare a precise real-world evacuation time — and why a calibrated, Cedar-specific City analysis would give the Planning Commission the missing local number. This model identifies and bounds that missing calculation. It does not replace professional evacuation engineering.

• A project-specific Cedar evacuation clearance calculation using the applicant’s 1 PM, 9 PM and overnight demand.
• Verified existing-household route assignment and evacuation vehicle demand for the local Cedar feeders.
• Measured or calibrated sustained discharge rates for Cedar/Alabama, Cedar/Chickasaw and Cedar/Seneca under evacuation conditions.
• An explicit School Canyon gate opening and operation assumption, with a sensitivity if the gate is delayed or unavailable.
• A clear separation between local Cedar clearance and the downstream North Ventura calculation, linked rather than conflated.
• Identification of any evacuation traffic-control measures relied upon, whether they are enforceable, and who implements them.