1001 Smart Cities

Permanent project revision

ATSAC Citywide Adaptive Traffic Signals

Revision 2026-10-14-baseline · effective 2026-10-14

Current revision. This is the snapshot used by the live entity page.

unreviewed

Created the first structured Evidence Passport with 12 claims and 7 source dossiers.

sha256:582d32586787654f81029d400ec13148a489fbbb0c7c9c9b3b548e5b4a31afe2
All revisions → Current entity page →

Change set

  • add /evidencePassport — Added claim-level evidence mapping and source dossiers.
  • add /revisionHistory — Established a permanent, hash-addressed baseline revision.
12
of 12 claims mapped
7
source dossiers
5
publication dates recorded
0
archives linked
0
exact locators
0
content captures hashed

Claims, one by one

The text below is copied verbatim from the published record. Each claim names the source dossiers that carry it; caveats stay attached to the claim they qualify.

Claim 1 clm-94422b217c316714 descriptive
LADOT's in-house traffic-signal system
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
LADOT says its staff invented the technology; Governing reports the computer systems were developed in-house and maintained internally.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. LADOT — ATSAC (authority)
  2. Governing — L.A. traffic system completed (press)
Claim 2 clm-6578bd94675ad21d quantitative
first deployed for the 1984 Olympics with 118 signals
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Spectrum News: in 1984 the system was able to control 118 traffic signals.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Spectrum News 1 — LA upgrades traffic control for 2028 Olympics (press)
Claim 3 clm-a0319d6f84f73095 quantitative
by 2024 connected more than 4,900 signals through 26,000+ sensors and more than 590 cameras
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
LADOT's key-figures sheet (revised November 2024) and fact sheet list 4,900+ signals, 26,000+ sensors/detectors and 590+ CCTV cameras.
Caveat
The figures are printed in an image on the programme page; the fact-sheet text is the readable form.

Sources carrying this claim

  1. LADOT — ATSAC (authority)
  2. LADOT — ATSAC fact sheet (authority)
Claim 4 clm-3a5172d32ba41337 quantitative
Los Angeles finished synchronising every signal citywide in February 2013
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Patch (21 February 2013): the last of the nearly 4,400 signals were synchronised on Tuesday.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Patch — Final L.A. Traffic Signals Synchronized (press)
Claim 5 clm-23d78e243f21b3b8 descriptive
LADOT called it the largest US city with remote control of every signal
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Governing attributes to LADOT that Los Angeles is the largest city in the country with complete remote control over every traffic light.
Caveat
A claim by the operator, not an independent comparison.

Sources carrying this claim

  1. Governing — L.A. traffic system completed (press)
Claim 6 clm-17996373c1a0f1b5 quantitative
In 2022 the control centre moved to a larger site and was expanded ahead of the 2028 Olympics
Published field
snippet · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Spectrum News: the new ATSAC headquarters opened on an upper floor of the Caltrans building, a larger space reflecting an expansion of the system, with LA28 present.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Spectrum News 1 — LA upgrades traffic control for 2028 Olympics (press)
Claim 7 clm-cf2d20989c432f6d quantitative
LADOT reported average citywide speeds up from 15 to 17.3 mph and intersection delays down 12 percent
Published field
impact · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Route Fifty, citing the city transportation department via the Los Angeles Times: speed from 15 to 17.3 mph citywide, intersection delays down 12 percent.
Caveat
No method or baseline period is given for these figures.

Sources carrying this claim

  1. Route Fifty — L.A. synchronizes traffic signals, but drivers might not notice (press)
Claim 8 clm-cf947ff7c72d76dc quantitative
A May 2020 state audit of two state-funded adaptive-control projects found the city had achieved the expected benefits
Published field
impact · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The Department of Finance's Office of State Audits and Evaluations concluded the City achieved the expected project benefits/outcomes for both projects.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. California Department of Finance — audit of two Proposition 1B signal projects, City of Los Angeles (May 2020)
Claim 9 clm-5225a6af9f970a49 quantitative
its floating-car studies showed a 4 to 9 percent reduction in travel time
Published field
impact · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The audit tables quote the Final Delivery Reports: the floating car study showed a 4 to 9 percent reduction in travel time.
Caveat
The studies were the city's own; the auditors checked that they supported the reported benefits.

Sources carrying this claim

  1. California Department of Finance — audit of two Proposition 1B signal projects, City of Los Angeles (May 2020)
Claim 10 clm-32f539f8c9e8ac6d quantitative
For one project the original study could not be found and was redone in November 2019
Published field
impact · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Finding 1: the City could not provide the floating car study cited in the report and conducted an additional study in November 2019.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. California Department of Finance — audit of two Proposition 1B signal projects, City of Los Angeles (May 2020)
Claim 11 clm-058d65273a8bdb51 descriptive
Even a citywide synchronised network buys modest gains — 'a smoother kind of slow', with more people travelling as speeds improve
Published field
lesson · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
Route Fifty quotes the Los Angeles Times' 'smoother kind of slow' and a USC engineer: improved traffic speed leads to more people traveling.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. Route Fifty — L.A. synchronizes traffic signals, but drivers might not notice (press)
Claim 12 clm-42ea200e44096b00 descriptive
state auditors could confirm one project's benefits only after the city repeated a lost floating-car study
Published field
lesson · verbatim
Mapping
mapped · no interpretation or interpolation added by this file
What the mapping says
The audit found the original study missing and accepted the benefits on the strength of the November 2019 repeat study.
Caveat
No claim-specific caveat recorded

Sources carrying this claim

  1. California Department of Finance — audit of two Proposition 1B signal projects, City of Los Angeles (May 2020)

Source dossiers and revision state

This layer records what is known about each source, what is still missing, and the exact snapshot this page is rendering. A missing date, archive or hash stays visible as missing.

unreviewed Revision 2026-10-14-baseline effective 2026-10-14 · created 2026-10-14

Awaiting operator and domain-expert review; publication of this revision implies neither.

sha256:582d32586787654f81029d400ec13148a489fbbb0c7c9c9b3b548e5b4a31afe2
Revision history → Permanent version link → Machine-readable record → Evidence Constitution →
12
of 12 claims mapped
7
source dossiers
5
publication dates recorded
0
archives linked
0
exact locators
0
content captures hashed

Governance facts carried by the record

Operator
Los Angeles Department of Transportation (LADOT)
Actor types
city-government
Funding model
public
Funding description
Not recorded
Cost
Not recorded
Ownership
Not recorded
Decision rights
Not recorded
Exit conditions
Not recorded

7 source dossiers

LADOT — ATSAC (authority) ladot.lacity.gov · 2 linked claims

Open original source ↗

Stable source ID
src-451adf25987df274
Publisher
Name not classified · ladot.lacity.gov
Type / language
web-page · language not classified
Published
Not recorded
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-10-14
Dossier created
2026-10-14
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

LADOT's programme page: real-time detector loops, cameras at major intersections, signal timing changed as traffic changes; its key-figures sheet (revised November 2024) lists 4,900+ signals, 26,000+ sensors and 590+ CCTV cameras, and estimates a 32% cut in travel delays against a system without automated control.

Descriptive only — not page/paragraph exact
Claims linked
Patch — Final L.A. Traffic Signals Synchronized (press) patch.com · 1 linked claim

Open original source ↗

Stable source ID
src-efd1c8147c051a10
Publisher
Name not classified · patch.com
Type / language
web-page · language not classified
Published
2013-02-21
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-10-14
Dossier created
2026-10-14
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Reports that the last of Los Angeles' nearly 4,400 traffic signals were synchronised, completing a $410 million effort; LADOT's design aim was 12% faster travel speed and 16% less time in traffic.

Descriptive only — not page/paragraph exact
Claims linked
Spectrum News 1 — LA upgrades traffic control for 2028 Olympics (press) spectrumnews1.com · 2 linked claims

Open original source ↗

Stable source ID
src-bde2a4debb480aa8
Publisher
Name not classified · spectrumnews1.com
Type / language
web-page · language not classified
Published
2022-11-30
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-10-14
Dossier created
2026-10-14
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Ribbon-cutting for the new ATSAC centre ahead of the 2028 Games: the system controlled 118 signals in 1984 and now manages 4,850; renamed Advanced Transportation System and Coordination.

Descriptive only — not page/paragraph exact
Claims linked
California Department of Finance — audit of two Proposition 1B signal projects, City of Los Angeles (May 2020) ig.dot.ca.gov · 4 linked claims

Open original source ↗

Stable source ID
src-a84ca672c832a702
Publisher
Name not classified · ig.dot.ca.gov
Type / language
pdf · language not classified
Published
2020-05-18
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-10-14
Dossier created
2026-10-14
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Performance audit requested by Caltrans of two adaptive-control projects funded with $18 million of Proposition 1B money: expected benefits achieved, floating-car studies showed a 4 to 9 percent reduction in travel time; for one project the City could not provide the original study and conducted a new one in November 2019.

Descriptive only — not page/paragraph exact
Claims linked
Governing — L.A. traffic system completed (press) governing.com · 2 linked claims

Open original source ↗

Stable source ID
src-3650726666efd9f3
Publisher
Name not classified · governing.com
Type / language
web-page · language not classified
Published
2013-03-25
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-10-14
Dossier created
2026-10-14
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Reports completion of the network; according to LADOT, Los Angeles is the largest city in the country with complete remote control over every one of its traffic lights.

Descriptive only — not page/paragraph exact
Claims linked
Route Fifty — L.A. synchronizes traffic signals, but drivers might not notice (press) route-fifty.com · 2 linked claims

Open original source ↗

Stable source ID
src-e1e112322238c37a
Publisher
Name not classified · route-fifty.com
Type / language
web-page · language not classified
Published
2013-04-04
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-10-14
Dossier created
2026-10-14
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

Citing LADOT via the Los Angeles Times: average citywide speed up from 15 to 17.3 mph and intersection delays down 12 percent, a 'smoother kind of slow'; a USC engineer notes that faster traffic leads more people to travel.

Descriptive only — not page/paragraph exact
Claims linked
LADOT — ATSAC fact sheet (authority) ladot.lacity.gov · 1 linked claim

Open original source ↗

Stable source ID
src-f4ef96fea2db4baa
Publisher
Name not classified · ladot.lacity.gov
Type / language
pdf · language not classified
Published
Not recorded
Updated
Not recorded
Source last checked
No source-level check date
Record last verified
2026-10-14
Dossier created
2026-10-14
Retrieved copy
No local capture recorded
Archive
No archived copy linked
Content hash
No captured content hash
Locator
Open the recorded source note

LADOT fact sheet: over 4,900 signalised intersections, over 26,000 vehicle detectors and over 590 CCTV cameras; describes the system as adaptive; its benefits section cites a 2013 Texas A&M study of signal synchronisation in general, not of ATSAC.

Descriptive only — not page/paragraph exact
Claims linked
Known limits of this file
  • Publisher names and source languages have not yet been classified; domains are recorded without guessing.
  • Existing source notes are descriptive locators, not page- or paragraph-exact citations.
  • A missing archive, publication date or content hash is shown as null rather than inferred.
  • The project-level evidence grade ranks the strongest source in the entry; it is not a truth score for every claim.