120
KSI Total
2015–2025 excl. 2020
22
Fatalities
People killed
662
Visible Injuries
City streets
2,029
Total Collisions
City streets only
5.9%
KSI Rate
120 / 2,029
18.9%
Alcohol KSI Rate
vs 4.8% non-alcohol
Annual collision trend by severity
2015–2025 excl. 2020 — gap marks excluded year
Severity breakdown
All city street collisions
Collision type distribution
Count by type
Primary collision factor
Top contributing factors
Collisions by hour of day
Red=late night · Yellow=PM peak
Day of week
Volume by weekday
What vehicle hit
Motor vehicle involved with
High Injury Network Explorer
Sorted by KSI · All years 2015–2025 excl. 2020 · City streets only
Era Comparison
2015–2019 (pre-COVID) vs 2021–2025 (post-COVID) Equal 5-year windows · 2020 excluded · All metrics normalizedKSI rate per year — trend
Blue=2015–19 · Orange=2021–25
Volume per year
Crash count trend by era
Collision type — KSI rate shift
Blue=era A · Orange=era B · Higher = more deadly per crash
Primary factor — volume/year
Is the mix of causes changing?
HIN Corridor Changes: 2015–19 vs 2021–25
The Safety Story: 2015–2019 vs 2021–2025
Equal 5-year periods · 2020 excluded · Stats normalized for fair comparisonCatastrophic Post-COVID KSI Surge
+72.0%
KSI rate surged from 4.47% to 7.69% — a 72.0% increase. One of the highest post-COVID surges in Contra Costa County. Urgent systemic intervention required.
Speed: #1 Cause of Crashes & KSI
3.0% → 3.8%
Unsafe Speed is the #1 PCF in Walnut Creek with 485 crashes. Speed KSI rate: 3.0% (era A) → 3.8% (era B). Physical calming, feedback signs, and road diet evaluation are the priority responses.
YGNACIO VALLEY RD: Worsening
10 → 17 KSI
YGNACIO VALLEY RD is the #1 HIN corridor with 27 total KSI (7 fatal). KSI worsening era A→B — immediate capital intervention warranted.
HIN: Danger Spreading
13 new corridors
13 new corridors emerged in 2021–25 not present in 2015–19. 15 corridors persist across both eras. Systemic citywide programs needed alongside targeted corridors.
Alcohol: Persistent Risk
13.7% → 23.3%
Alcohol KSI rate rose from 13.7% to 23.3%. At 23.3%, alcohol crashes remain 3.9× more deadly than non-alcohol. DUI enforcement must intensify.
Bicycle Safety on HIN Corridors
183 crashes
183 bicycle collisions with 14 KSI. Bike conflicts concentrated on HIN corridors. Class IV protected bike lanes and signal detection are the priority countermeasures.
Dark KSI Surging
9.4% → 12.7%
Dark-condition KSI rate surged: 9.4% → 12.7%. 462 dark crashes, 51 KSI. LED intersection lighting and retroreflective backplates deliver the highest BCR return.
Volume vs Severity
224/yr → 182/yr
Crash volume: 224/yr (era A) → 182/yr (era B). Volume fell but KSI rate surged — severity crisis, not a volume crisis.
Fatal Intersection: YGNACIO VALLEY RD & OAK GROVE RD
3 KSI
YGNACIO VALLEY RD & OAK GROVE RD — 3 KSI (1 fatal), 23 crashes. Era A: 1 KSI → Era B: 2 KSI. Immediate capital investment warranted.
AI-Powered Safety Insights
Multivariate patterns · Walnut Creek city streets 2015–2025 (excl. 2020) · Ranked by policy impact
Alcohol Multiplier Effect
3.9×
Alcohol KSI rate: 18.9% vs 4.8% non-alcohol. 7.8% of crashes, 25.0% of KSI.
DUI EnforcementDarkness Amplifies Severity
28.4%
Of pedestrian crashes occur in dark. After-dark ped crashes are 1.7× more likely to be fatal/severe than daytime (23.2% vs 13.9% KSI rate).
Street LightingPedestrian KSI Rate Elevated
17.3%
Pedestrian KSI rate: 17.3% across 243 crashes (42 KSI). 28.4% of ped crashes in dark — LED lighting and RRFB crossings are the priority response.
Ped InfrastructureLate Night KSI Spike
16.4%
KSI rate 0–5 AM is 4.0× higher than midday (4.1%). 0.0% of crashes, concentrated fatal risk window.
High-Severity WindowAlcohol + Dark: Compound Risk
23.5%
Alcohol AND dark: KSI rate hits 23.5% — well above city average of 5.9%. Disproportionate harm from this combination.
Compound RiskWeekend Night Danger Window
16.3%
Fri/Sat/Sun after 9 PM: 16.3% KSI rate. 135 crashes, 22 KSI. Targeted enforcement these 3 nights addresses disproportionate fatal risk.
Enforcement TimingCollision type × severity heatmap
Darker = higher KSI rate
KSI rate by time of day
When is each crash most likely to be fatal or severe?
Annual KSI vs total collisions
Volume declining but severity rising — the key trend
Top 5 corridors — KSI persistence
Dangerous year after year
—
Showing
—
KSI
—
Fatal
—
KSI Rate
Severity
Fatal
Severe
Visible
Pain
SS4A FY2026 Implementation Grant — Project Portfolio
Three plans based on 2021–2025 post-COVID crash data · May 26, 2026 deadline
HSIP Cycle 13 — Project Recommendations
Cross-cycle C8–C12 analysis · Walnut Creek award history · 2021–2025 crash data
$5M–$18M est. portfolio
HSIP Grant Intelligence Module
Synthesized from Cross-Cycle Analysis C8–C12 · Countermeasure Trends · C12 Report & Funded Projects List
$2.46M
Walnut Creek HSIP Won
C12
3
Projects Funded
Prior award cycles
$1.15B
Program Total
1,281 projects C8–C12
$5–18M
C13 Portfolio Target
6 recommendations
Walnut Creek HSIP Application History
C13 Statewide Intelligence
🚀 Rising Countermeasures (C8→C12)
Gaining frequency & funding — prioritize for C13
LPI: 0→33 projects · +33
RRFB/Beacons: 11→57 · +46
Retroreflective Backplates: 1→23 · +22
Class IV Bike Lanes: 14→31 · +17
Raised Medians: 8→19 · +11
📉 Declining Countermeasures
Losing funding share — supplement but don't lead with these
Signal Timing Only: 45→12 · -33
Striping/Delineation Only: 28→9 · -19
Guardrail: 22→8 · -14
Rumble Strips Only: 11→4 · -7
BCR Sweet Spot
$1.5M–$4M
Walnut Creek should target $1.5–3.5M per BCR application. Stack 3+ countermeasures for highest BCR score.
Best Win Strategy
3-CM Stack
C12 winners averaged 3+ countermeasures per application. Prior C12 wins provide competitive positioning.
VRU Pool
426 VRU
243 ped + 183 bike = 56 KSI. Qualifies for VRU Special Rule set-aside.