DISCRETIONARY
REVIEW REQUIRED
Controlling FindingControlling finding: Shasta Road adds 27.43 min of marginal evacuation clearance time — 12.2× the 2.25-min threshold (45 min × 5%, Very High FHSZ, NIST TN 2135). Exceeds threshold by 25.18 min.
Analysis
A
Applicability Threshold
Minimum 15 dwelling units — integer comparison, no discretion
IN SCOPE
80 dwelling units proposed ≥ 15-unit threshold.
Project size threshold: 15 dwelling units
(ITE Trip Generation de minimis; SB 330, Gov. Code §65913.4).
B
Site Parameters
CAL FIRE FHSZ classification — sets road capacity degradation factor and ΔT threshold for clearance analysis
VERY HIGH FHSZ
Project site: Zone 3 (Very High) (source: CAL FIRE OSFM)
CAL FIRE HAZ_CLASS: 3 —
vhfhsz; road capacity reduced to 0.35× HCM base
(HCM Exhibit 10-15/10-17 composite + NIST Camp Fire validation).
ΔT threshold: reduced proportionally (shorter safe egress window
applies; see Clearance Analysis below).
Mobilization rate: 0.90 (NFPA 101 constant — unaffected by
FHSZ zone; ~10% zero-vehicle HH per Census ACS B25044).
C
Evacuation Clearance Analysis
Route identification (0.5 mi radius) + per-path ΔT test — this is the operative determination step
EXCEEDS THRESHOLD
111 serving route segments within 0.5 mi (OSM evacuation route network).
ΔT threshold: 45 min safe egress window (NIST TN 2135, Very High FHSZ) × 5% max project share = 2.25 min
Project vehicles: 180
(units × 2.5 vpu × 0.90 NFPA 101 constant).
Effective capacity = HCM raw × 0.35 hazard degradation.
| Path | Bottleneck Segment | FHSZ Zone |
Eff. Cap (vph) | ΔT (min) | Threshold |
Margin | Result |
| proj_100565801_243670952 | Shasta Road
Two-lane · 25 mph · 2 ln → HCM 1,125 × 0.35 = 394 vph | Very High FHSZ | 394 | 27.43 | 2.25 | +25.18 | CONTROLLING |
SB 79 Transit Proximity
Transit stop within 0.5 mi — does not affect this determination
INFORMATIONAL
Determination
DETERMINATION →
Project meets the 15-unit applicability threshold and 1 serving path(s) exceed the ΔT threshold of 2.25 min (max ΔT: 27.4 min). FHSZ Zone 3 (vhfhsz) — road capacity degradation applied. Mobilization: 0.90 (NFPA 101 design basis, constant). Discretionary review required. Legal basis: AB 747 (California Government Code §65302.15) — General Plan Safety Element mandatory update for evacuation route capacity analysis; HCM 2022 (Highway Capacity Manual, 7th Edition) — effective capacity with hazard degradation; NFPA 101 (Life Safety Code) — 0.90 mobilization design basis (100% occupant evacuation, adjusted for ~10% zero-vehicle households per Census ACS B25044); NIST TN 2135 (Maranghides et al.) — safe egress windows by hazard zone.
Wildland Evacuation Analysis: DISCRETIONARY
SB 79 Transit Proximity (Informational): NOT_APPLICABLE
Legal authority: AB 747 (California Government Code §65302.15) — General Plan Safety Element mandatory update for evacuation route capacity analysis; HCM 2022 (Highway Capacity Manual, 7th Edition) — effective capacity with hazard degradation; NFPA 101 (Life Safety Code) — 0.90 mobilization design basis (100% occupant evacuation, adjusted for ~10% zero-vehicle households per Census ACS B25044); NIST TN 2135 (Maranghides et al.) — safe egress windows by hazard zone
Required Next Steps
This project requires discretionary review under AB 747
(Gov. Code §65302.15). The objective standards analysis has determined that this project
would add more than 2.25 minutes of marginal evacuation clearance time (ΔT)
on one or more serving evacuation paths in hazard zone vhfhsz
(maximum ΔT: 27.43 min vs. 2.25-min threshold).
ΔT exceedance identified on 1 path(s): Path proj_100565801_243670952 — bottleneck: Shasta Road (ΔT 27.4 min vs 2.25-min threshold)
- Environmental Impact Report (EIR) required under CEQA
(Pub. Resources Code §21100) — evacuation clearance time impact must be analyzed
as a significant transportation impact.
- Evacuation Clearance Time Analysis: Applicant shall commission
a study conforming to the JOSH v3.4 ΔT methodology (AB 747 / Gov. Code §65302.15),
analyzing marginal evacuation clearance time on all serving paths within 0.5 miles,
using NFPA 101 design basis mobilization rate (0.90 constant) and HCM 2022
hazard-degraded capacity factors.
- Public Hearing before the Planning Commission is required prior to any
project approval (Gov. Code §65905).
- Fire Department Review: Submit project plans to the Fire Marshal for
review of evacuation access, egress widths, and compliance with Fire Code §503.
- Mitigation Measures or Project Redesign: Applicant must demonstrate
— through the clearance time analysis — either (a) that mitigation measures reduce ΔT
below 2.25 minutes on all serving paths, or (b) that the project scope
(units, stories, or both) is reduced to fall within the ΔT threshold, to qualify for
ministerial review.
- Approval is not ministerial until the ΔT exceedance is mitigated or the project
is redesigned to fall within the ΔT threshold on all serving evacuation paths.
Legal Authority
Every numerical value in this determination is derived mechanically from the authorities below.
No engineering judgment was exercised. The same methodology is applied uniformly to all projects
under AB 747.
| # |
Authority |
Published / Adopted |
Parameter |
Value Applied |
| 1 |
AB 747, Gov. Code §65302.15 |
2021 Ch. 394 |
Analysis mandate |
— |
| 2 |
CAL FIRE OSFM FHSZ (state-adopted SRA map) |
Current SRA designation |
Hazard zone |
vhfhsz — Zone 3 (Very High) |
| 3 |
NIST TN 2135 (Maranghides et al., Camp Fire) |
2021 |
Safe egress window (Very High FHSZ) |
45 min |
| 4 |
Standard engineering significance criterion |
— |
Maximum project share of egress window |
5% |
| → |
Derived from ③ × ④ |
ΔT threshold for this location |
45 × 0.05 = 2.25 min |
| 5 |
HCM 2022 Exhibit 12-7 (TRB 7th Ed.) |
TRB 2022 |
Road HCM base capacity (controlling: Shasta Road
Two-lane, 25 mph, 2 lanes) |
1,125 vph |
| 6 |
HCM 2022 Ex. 10-15/10-17 + NIST Camp Fire validation |
TRB 2022 / NIST 2021 |
Hazard capacity degradation (Very High FHSZ) |
1.00× |
| → |
Derived from ⑤ × ⑥ |
Effective bottleneck capacity |
394.0 vph |
| 7 |
NFPA 101 Life Safety Code, 2021 Ed. |
2021 |
Evacuation mobilization rate (design basis) |
0.90 (constant) |
| 8 |
U.S. Census ACS B25044 |
2020 5-yr |
Zero-vehicle household adjustment (~10%) |
Incorporated in NFPA 101 constant |
| → |
Formula result |
ΔT (marginal evacuation clearance time) |
27.43 min vs. 2.25-min limit |
Core Formula
ΔT = (project_vehicles / bottleneck_effective_capacity_vph) × 60 + egress_penalty
project_vehicles = 80 units × 2.5 vpu × 0.90 (NFPA 101 constant)
= 180 vph
egress_penalty = 0 (building < 4 stories)
Flagged when ΔT > 2.25 min (threshold = 45 min × 5%)
This determination applies the above authorities mechanically. No engineering judgment was
exercised. The same methodology is applied uniformly to all projects under AB 747.
Audit trail not available: determination_37_8914_n122_2494_80u.txt
Appeal Rights
This determination is the result of an objective, algorithmic analysis under adopted city
standards. All inputs, calculations, and threshold comparisons are recorded in the attached
audit trail and are fully reproducible.
An applicant who disagrees with this determination may appeal within 10 business days
of the date of this letter to the City of Berkeley Planning Commission. The appeal must
identify a specific factual error in the data inputs or threshold parameters. Engineering
judgment is not a basis for appeal — these are objective standards.
For questions, contact the Planning Department. Reference the case number on this letter.