CET traffic control centre and São Paulo's observed congestion index
CET, São Paulo's municipal traffic company, has run the city's signals and control rooms since 1976. Its famous daily congestion figure — kilometres of jams — came not from sensors but from observation: interns on rooftops, later patrol cars, field posts and cameras covering a fixed 868 km sample. Only since mid-2020 has CET derived it from Waze data, widened to the city's roughly 20,000 km of streets in March 2023. The signal estate is still largely fixed-time: 1,677 of about 6,751 signalised crossings had been converted to adaptive SCATS control by July 2026, under a 17-year addendum folding signal upkeep into the city's public lighting PPP with Ilumina SP. In October 2024 the city took down Sinal Verde, the page that had shown since 2014 which signals were dark.
City-reported 12.16% less congestion and 5.72% more circulation capacity in areas with modernised signals; 1,677 of about 6,751 signalised crossings converted by July 2026 (Prefeitura de São Paulo figures, not independently audited).
🎓 Lesson
The measurement layer and the control layer can be decades apart. São Paulo published a world-famous congestion number produced by human observers for some forty years, while most of its signals still ran fixed timings — and no independent evaluation of either has been published.
Evidence🏛️ Official
Scale🏙️ City-wide
Cost≈R$1.12bn over 17 years for signal maintenance and modernisation (PPP addendum); R$725.5M invested by July 2026
FundingMunicipal, via the Ilumina SP public lighting PPP addendum
Sources
↗ Prefeitura de São Paulo — Semáforos inteligentes reduzem lentidão e tornam o trânsito mais fluidoCity page dated 25 July 2026. Establishes that the modernised signals run SCATS, which 'monitora o fluxo de veículos em tempo real e ajusta automaticamente os ciclos'; 1,677 intersections modernised, 217 in final implementation, 689 approved, target 2,583; R$725.5M invested; and the operator-supplied results (−12.16% congestion, +5.72% capacity overall; +12.05% capacity and −26.04% congestion in the Southeast and East zones). All performance figures here are city-supplied.
↗ Prefeitura de São Paulo — CET amplia medição do trânsito para todas as vias da cidadeThe load-bearing source for the entry's spine. States that the Monitrans indicator has been produced since the 1980s 'mediante a observação das rotas operacionais, dos postos avançados de campo, viaturas, agentes e câmeras de monitoramento', and that 'antes a medida era feita com pessoas em cima dos prédios. Eram estagiários que mediam o trânsito'. Also establishes the 868 km monitored sample (since 2010), the adoption of the Lentidão CET-Waze indicator in mid-2020, the extension to the city's ~20,000 km of streets from 3 March 2023, and that the Waze-based indicator proved three times more sensitive than Monitrans.
↗ Prefeitura de São Paulo — Prefeitura amplia PPP e Ilumina SP assume rede de semáforosDated 1 September 2022. Establishes that São Paulo has 'o maior parque semafórico do país, com 6.666 cruzamentos e travessias semaforizadas' (a city claim, reported here as attributed rather than asserted); the 17-year, R$1.12bn addendum transferring signal maintenance, replacement and modernisation to concessionaire Ilumina SP including vandalism and cable-theft costs; the stated R$138M saving against a standalone tender; and that CET retains traffic engineering and operational oversight.
↗ Metrópoles — Com concessão, Nunes tira do ar site que mostra semáforos apagadosEstablished press, 16 October 2024. The entry's main counterweight. Establishes that the Sinal Verde page — launched October 2014, updated by CET in real time, showing the share and location of signals off or flashing yellow — was taken offline after the Ilumina SP concession began, with the city saying it was being 'reavaliada em razão do início de manutenção e modernização do parque semafórico da cidade'. Also gives 6,751 signalised crossings, fewer than 10% with backup power, and 48 signals still dark four days after the 11 October 2024 storm.
↗ TomTom Traffic Index — São PauloFETCH FAILED — the page is JavaScript-rendered and returned no figures to automated retrieval. Listed for the editor as the canonical independent congestion series, but NO figure from it is used in this entry. Widely circulated numbers (e.g. '132 hours lost in 2025') could not be verified sentence-level and were therefore cut. As it stands, no independent evaluation of CET's control centre or the SCATS retrofit was found.
↗ Prefeitura de São Paulo — CET, competências e atribuições definidas por leiInstitutional page. Establishes CET as a mixed-economy company with majority municipal capital, created in 1976, responsible for traffic engineering and operation in the municipality — the basis for yearStart and for the scope boundary against state operators (DER-SP, ARTESP, Metro, CPTM).
📎 Cite this project
1001 Smart Cities (2026). “CET traffic control centre and São Paulo's observed congestion index” — São Paulo, Brazil. The Smart City Atlas. https://1001smartcities.org/projects/sao-paulo-cet-traffic-control/ (last verified 2026-07-26). Data: CC BY 4.0.
The underlying data is free to reuse with attribution — see the open data page.
