Roadscape corridor packet - screening draft
Fremont Blvd @ Mowry Ave
Fremont, CA. Real Caltrans data separated from screening estimates and field gaps - same format as the Fremont report, auto-assembled from the free-pool pipeline (corridor data + research + swept-path). Not PE-stamped.
Nearby AADT context220,000freeway context - not the arterial
Peak hour15,300Caltrans, where available
Swept-path (worst)FAIL5 turns run AASHTO off-track
Evidence statusScreeningnot PE-stamped
Roadscape does not add crash-reduction factors together. Ranges are evidence references, not promises. Combined outcomes require verified volumes, local crash history, final geometry, and licensed engineering review.
0. Proof Status
Real Caltrans/public facts kept separate from Roadscape estimates and from what still has to be measured in the field.
Real / measured
3 items- nearby state-route AADT context (measured): I-880 @PM 2.283 - FREMONT, JCT. RTE. 262 EAST, AADT 220,000, peak 15,300. [FREEWAY/interchange context - NOT this arterial's own volume]
- 8 nearby Caltrans state-route segments matched (source: Caltrans public AADT ArcGIS).
- Swept-path scene loaded: Fremont corridor - Fremont Blvd -> Mowry Ave -> I-880 N (Exit 17) - 5 modeled turns (Roadscape geometry).
Estimated
3 assumptions- Classification: surface arterial (verify against city functional-class map).
- Peak-hour v/c, delay, and exposure: screening estimates until field-measured.
- This corridor own-volume is still a screening gap unless the Caltrans segment directly matches the corridor. Use city counts or Roadscape video counts before citing flow/v-c.
Needs field measurement
4 gaps- Turning-movement + ped/bike counts (Roadscape video analyzer - no field count in hand yet).
- Verified SWITRS/TIMS crash history for this corridor (export from tims.berkeley.edu tims-crashes.csv).
- Curb-to-curb width + controlling design-vehicle swept-path (run the Roadscape swept-path per turn).
- Fire/EMS route status + emergency access confirmation.
1. Corridor Overview
The corridor
JurisdictionFremont, CA
Classsurface arterial (verify)
AADT context only220,000 (freeway nearby)
Segments matched8
Nearby measured segments (Caltrans AADT)
I-880 @PM 2.283220,000 - FREMONT, JCT. RTE. 262 EAST
I-880 @PM 3.247198,000 - FREMONT, LANDING ROAD/ FREMONT BOU
I-880 @PM 10.3195,000 - FREMONT, NORTH JCT. RTE. 84
I-880 @PM 11.404195,000 - FREMONT, FREMONT BOULEVARD
I-880 @PM 4.712186,000 - FREMONT, DURHAM ROAD/ GRIMMER BOUL
I-880 @PM 6.239186,000 - FREMONT, STEVENSON BOULEVARD
2. Flow Diagnosis
Volume context
Top AADT220,000
Peak hour15,300
SourceCaltrans (measured)
Corridor own-volumeneeds local/city or video count
This AADT is context only. The corridor own peak-hour volume must be measured or sourced from the city before flow/v-c is cited.
Movement counts
SourceREPRESENTATIVE - pending Roadscape video count
AM/PM throughfield count needed
Turnsfield count needed
Ped/bikefield count needed
3. Geometry / Swept-Path
Each turn run through the Roadscape swept-path engine (AASHTO low-speed off-tracking) for real design vehicles. Controlling result: FAIL at Mowry Ave -> interchange approach (RIGHT). Screening-grade - verify field geometry.
Turn 1: Fremont Blvd -> Mowry Ave (LEFT study int.)
Angle90
Curb radius40 ft
Turn radius46 ft
Available width~17 ft
| Design vehicle | Off-track (ft) | Swept width (ft) | Fit |
|---|
| P - Passenger car | 1.3 | 8.3 | PASS |
| SU-30 - Single-unit truck | 4.6 | 12.6 | PASS |
| BUS-40 - City transit bus (40ft) | 7.4 | 15.9 | ENCROACHES |
| WB-40 - Semi (WB-40) | 11.7 | 20.2 | ENCROACHES |
| WB-67 - Interstate semi (WB-67) | 42.3 | 50.8 | ENCROACHES |
Field confidencehigh Fremont Hub / Target
Turn 2: Mowry Ave -> interchange approach (RIGHT)
Angle90
Curb radius30 ft
Turn radius35.5 ft
Available width~14.8 ft
| Design vehicle | Off-track (ft) | Swept width (ft) | Fit |
|---|
| P - Passenger car | 1.7 | 8.7 | PASS |
| SU-30 - Single-unit truck | 6.2 | 14.2 | ENCROACHES |
| BUS-40 - City transit bus (40ft) | 10.3 | 18.8 | ENCROACHES |
| WB-40 - Semi (WB-40) | 17.6 | 26.1 | ENCROACHES |
| WB-67 - Interstate semi (WB-67) | - | - | FAIL |
Field confidencemed past Goodwill(4025)/Metro PCS(4095), toward I-880
Turn 3: Interchange weave (RIGHT)
Angle90
Curb radius25 ft
Turn radius30.5 ft
Available width~14.1 ft
| Design vehicle | Off-track (ft) | Swept width (ft) | Fit |
|---|
| P - Passenger car | 2.1 | 9.1 | PASS |
| SU-30 - Single-unit truck | 7.5 | 15.5 | ENCROACHES |
| BUS-40 - City transit bus (40ft) | 13 | 21.5 | ENCROACHES |
| WB-40 - Semi (WB-40) | - | - | FAIL |
| WB-67 - Interstate semi (WB-67) | - | - | FAIL |
Field confidencelow I-880/Cedar interchange frontage
Turn 4: Interchange weave (LEFT)
Angle90
Curb radius25 ft
Turn radius30.5 ft
Available width~14.1 ft
| Design vehicle | Off-track (ft) | Swept width (ft) | Fit |
|---|
| P - Passenger car | 2.1 | 9.1 | PASS |
| SU-30 - Single-unit truck | 7.5 | 15.5 | ENCROACHES |
| BUS-40 - City transit bus (40ft) | 13 | 21.5 | ENCROACHES |
| WB-40 - Semi (WB-40) | - | - | FAIL |
| WB-67 - Interstate semi (WB-67) | - | - | FAIL |
Field confidencelow on-ramp approach
Turn 5: I-880 North on-ramp merge (Exit 17)
Angle40
Curb radius150 ft
Turn radius157.5 ft
Available width~21 ft
| Design vehicle | Off-track (ft) | Swept width (ft) | Fit |
|---|
| P - Passenger car | 0.4 | 7.4 | PASS |
| SU-30 - Single-unit truck | 1.3 | 9.3 | PASS |
| BUS-40 - City transit bus (40ft) | 2 | 10.5 | PASS |
| WB-40 - Semi (WB-40) | 3 | 11.5 | PASS |
| WB-67 - Interstate semi (WB-67) | 6.8 | 15.3 | PASS |
Field confidencemed Nimitz Fwy -> Oakland
Off-tracking uses the AASHTO low-speed radius formula. Radius = curb + half-lane; available width is a conservative screen. Field-verify curb radius + lane width before any official use. Not a substitute for AutoTURN + a licensed engineer.
4. Prescription Map
Screening candidates - not stacked. Backed by the free-pool research briefs; final call needs a PE.
Primary candidates
Dedicated right-turn pocketprimary
Lets right-turners queue out of the through lane where blocked-turn queues occur; keep the crossing short + protected.
Evidencerear-end/angle ~20-55% (reference)
Needsturning counts; queue events; curb-to-curb width
Signal retiming / protected turnprimary
Cheapest flow smoother; protected phase cuts turn crashes where they cluster.
Evidencedelay 10-30% (reference)
Needssignal plans; turn volumes; delay observation
Study instead
Road diet (43)study
Best-documented safety fix if daily traffic stays under ~20-25k; reclaims width. Verify this corridor's OWN volume first.
Evidence~19-47% crash reduction (reference)
Backfires whenADT above ~25k, or a true regional through-route
Complements
Leading Ped Intervalcomplement
Cheap signal change, strong ped safety record.
Evidence~13-59% ped crash reduction (reference)
Truck/bus turning-radius fitcomplement
Corners must fit the design vehicle so it doesn't off-track - balance vs. car turn speed past crosswalks.
Needsheavy-vehicle counts; swept-path template
5. Packet Grade and Value Path
Professional grade
CurrentB+ screening-grade
With local dataA- with local crash, arterial volume, video counts, and delay/exposure data
With reviewA+ with field verification and qualified professional sign-off
$75k-$120k per multi-intersection packet after crash data, local counts, measured video analysis, delay/exposure, field verification, and PE review
Value gaps
- Add 5-year TIMS/SWITRS crash data
- Add local arterial AADT, peak-hour counts, and turning-movement counts
- Add measured Roadscape video analysis with curb strikes, encroachments, queues, and screenshots
- Add delay and exposure calculations
- Add field-verified geometry for lane widths, curb radii, and turning paths
- Add qualified professional review/sign-off for official recommendations
6. What Must Be Measured Next
Field package
Agency ADT + classified turning counts
Multi-day AM/PM peaks
Verified SWITRS/TIMS crashes
Curb-to-curb widths
Queue length + delay
Bike/ped counts
Fire/EMS route status
Design-vehicle swept-path
Engineer review lane
This packet shows what the evidence supports, what it doesn't yet, and what to measure before a licensed engineer makes the call.
Research framing used (free-pool, self-evolving): 5 briefs.
Appendix
Nearby Caltrans AADT (all matches)
- I-880 @PM 2.283 - FREMONT, JCT. RTE. 262 EAST: AADT 220,000, peak 15,300
- I-880 @PM 3.247 - FREMONT, LANDING ROAD/ FREMONT BOULEVARD: AADT 198,000, peak 13,900
- I-880 @PM 10.3 - FREMONT, NORTH JCT. RTE. 84: AADT 195,000, peak 12,900
- I-880 @PM 11.404 - FREMONT, FREMONT BOULEVARD: AADT 195,000, peak 12,900
- I-880 @PM 4.712 - FREMONT, DURHAM ROAD/ GRIMMER BOULEVARD: AADT 186,000, peak 12,600
- I-880 @PM 6.239 - FREMONT, STEVENSON BOULEVARD: AADT 186,000, peak 12,800
- I-880 @PM 7.189 - FREMONT, MOWERY AVENUE: AADT 186,000, peak 11,900
- I-880 @PM 8.842 - FREMONT, SOUTH JCT. RTE. 84: AADT 185,000, peak 12,200
Research briefs
- crash modification factors cmf for common corridor treatment
- high traffic corridor scoping methodology ranking segments b
- right turn pocket vs shared lane the queue overflow tradeoff
- road diet feasibility check when converting a 4 lane undivid
- turning geometry swept path how off tracking dictates curb r