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You can help expand this article with text translated from the corresponding article in French. (March 2016) Click for important translation instructions. Machine translation, like DeepL or Google Translate, is a useful starting point for translations, but translators must revise errors as necessary and confirm that the translation is accurate, rather than simply copy-pasting machine-translated text into the English Misplaced Pages. Do not translate text that appears unreliable or low-quality. If possible, verify the text with references provided in the foreign-language article. You must provide copyright attribution in the edit summary accompanying your translation by providing an interlanguage link to the source of your translation. A model attribution edit summary is Content in this edit is translated from the existing French Misplaced Pages article at ]; see its history for attribution. You may also add the template {{Translated|fr|Système d'aide à la conduite, à l'exploitation et à la maintenance}} to the talk page. For more guidance, see Misplaced Pages:Translation.

The Système d'aide à la conduite, à l'exploitation et à la maintenance (SACEM) is an embedded, automatic speed train protection system for rapid transit railways. The name means "Driver Assistance, Operation, and Maintenance System".

It was developed in France by GEC-Alsthom, Matra (now part of Siemens Mobility) and CSEE (now part of Hitachi Rail STS) in the 1980s. It was first deployed on the RER A suburban railway in Paris in 1989.

Afterwards it was installed:

• on the Santiago Metro in Santiago, Chile;
• on some of the MTR lines in Hong Kong (Kwun Tong line, Tsuen Wan line, Island line, Tseung Kwan O line, Airport Express and Tung Chung line), all enhanced with ATO,
• on Lines A, B and 8 of the Mexico City Metro lines in Mexico City; and
• on Shanghai Metro Line 3.

In 2017 the SACEM system in Paris was enhanced with Automatic Train Operation (ATO) and was put in full operation at the end of 2018.

The SACEM system in Paris is to be enhanced to a fully fledged CBTC system named NExTEO. First to be deployed on the newly-extended line RER E in 2024, it is proposed to replace signalling and control on all RER lines.

Operation

The SACEM system enables a train to receive signals from devices under the tracks. A receiver in the train cabin interprets the signal, and sends data to the console so the driver can see it. A light on the console indicates the speed control setting: an orange light means slow speed, or 30 km/h (19 mph); a red light means full stop. If the driver alters the speed, a warning buzzer may sound. If the system determines that the speed might be unsafe, and the driver does not change it within a few seconds, SACEM engages the emergency brake. SACEM also allows for a reduction in potential train bunching and easier recovery from delays, therefore safely increasing operating frequencies as much as possible especially during rush hour.

References

1. "MTR > Tenders & Contracts". www.mtr.com.hk. Retrieved 2021-12-17.
2. "Mexico City (Mexico) Lines A, B and 8 - SACEM high performance Automatic Train Control for driver-based operation" (PDF; 600 kB). Siemens SAS; Infrastructure & Cities Sector; Mobility and Logistics Division. 2015-03-05. Retrieved 2017-12-23.
3. 张郁; 黄佩伟 (2004). "上海轨道交通3号线轨道电路分析" [An analysis of track circuits deployed on Shanghai Metro Line 3] (in Chinese). 城市轨道交通研究. Retrieved 2020-05-12.
4. "Alstom-developed Automatic Train Operation system successfully enters service on the RER A". ALSTOM Holdings. 2017-10-05. Retrieved 2017-12-23.
5. "RER E – soon one train ahead thanks to NExTEO …". SNCF Réseau. 2017-07-20. Retrieved 2017-12-23.
6. "Système d'Aide à la Conduite, à l'Exploitation et à la Maintenance". Institution of Railway Signal Engineers. 2003. Retrieved 2017-12-23.

External links

• Operation principles and examples with pictures in Hongkong

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