我國城市軌道交通信號系統發展方向探討

李中浩

(中國城市軌道交通協會專家與學術委員會榮譽委員,正高級工程師)

中國的城市軌道交通信號系統具有后發優勢,除了上世紀九十年代早期建設的幾條地鐵線路的信號系統外,幾乎全部采用CBTC(基于通信的列車控制)系統,實現了移動閉塞,這是幾代軌道交通信號人夢寐以求目標。隨著北京燕房線自主化的基于CBTC的FAO(全自動運行)列車控制系統開通以后,多家國內信號供應商擁有了自主化的FAO產品,并得到了工程驗證。中國城市軌道交通信號系統的發展進入了“無人(領跑)區”,我們必須自己回答,我國城市軌道交通信號系統向何處去。

談到方向,就必須認清軌道交通有別于其他交通模式的特點。無論列車跑的多塊,開的多密,有多少節車廂,軌道只有一條,這是唯一的專用資源,集中控制才能使唯一的專用資源在保證絕對安全的條件下發揮最大的效益,所以鐵路具有半軍事化的管理特征。鐵路通過按圖行車實現列車的集中調度指揮與控制,運行圖是關聯運輸需求和運輸能力的紐帶。

FAO是城市軌道交通運輸的發展方向,實現列車運行全過程的自動化,可以最大限度節省人力,提升運輸效率,保證運輸安全。FAO使信號系統的架構大大擴展了,凡是與列車運行安全、效率有關的專業,比如綜合監控系統、供電系統、屏蔽門、旅客導向系統等,都可以歸納到FAO系統內。系統大了,出現故障的幾率就大。考慮FAO系統的運行韌性,提升在故障環境下列車運行的效率,在故障條件下賦予列車自主運行的能力,成為發展中的需求。要實現這一目標,需要引入“故障導向安全運行”的理念。信號系統最顯著的特點是“故障導向安全”,這是指在任何情況下要保證列車運行的絕對安全。當采用FAO系統以后,故障導向安全的安全側發生了變化,安全側要求保證乘客的絕對安全,而不僅僅是保證列車裝備的絕對安全。引入故障導向安全運行的原則要求具有列車自主運行功能的FAO系統,要求具有有安全完整性要求的列車主動障礙物檢知的功能。

具有列車自主運行功能的FAO系統,是對FAO系統提出的特殊要求。需要強調:一是在FAO系統正常時,系統處于全自動運行狀態,不需要賦予列車自主運行的能力;二是市域快軌等中小運量系統,不必都采用具有列車自主運行功能的FAO系統。

運行圖指令的下達,傳統的路徑是下達給地面裝備,由地面裝備對軌道唯一資源進行聯鎖,形成列車安全運行的進路后,通知列車在指定范圍內按給定的速度行車。為了提高地面資源的利用率,也有將運行圖指令下達給列車,由列車向地面要資源,地面資源可以縮小聯鎖單元,結合車車通信等新的聯鎖條件,提高資源利用率、提升運輸效率。有些信號供應商把車車通信也看作一種信號制式,這是不對的,車車通信只是一種技術手段。

地鐵是以通勤流為主的大運量交通運輸工具,早晚高峰特征非常明顯,從縮短運行間隔、減少能耗的角度,針對這種運輸模式,靈活編組是剛需;如果能實現動態靈活編組將更有利于運輸組織。有一種動態靈活編組的形式是虛擬聯掛。技術上實現虛擬聯掛,一定要對列車的加速度進行控制,對列車的速度控制也更為精確,這樣才能具有撞軟墻功能;但是將虛擬聯掛用于運輸組織并且確保安全和帶來效益,還需要工程驗證。

我國城市軌道交通信號系統的發展進入無人區以后,信號系統的標準化顯得更為重要。為此,中國城市軌道交通協會組織編制了CMTCS(中國城市軌道交通列車運行控制系統)總則,歸納了城市軌道交通信號系統的本質需求,將其分為CMTCS0—CMTCS4五個種類。CMTCS0具有ATP(列車自動保護)功能,CMTCS1具有ATO(列車自動運行)功能,CMTCS2具有FAO功能,CMTCS3具有故障條件下列車自主運行功能,CMTCS4具有動態靈活編組功能。將互聯互通的需求作為CBTC系統的基本需求。各個級別之間沒有誰比誰更先進一說,只有誰比誰更適用的選擇。

在城市軌道交通進入網絡化的時代,我國的軌道交通建設正在從高速發展階段轉向高質量建設階段,其經濟性、可持續發展的要求尤其要引起重視。所有的運輸裝備要以滿足運輸需求為目的,要滿足交通強國提出的安全、高效、便捷、綠色、經濟的總體方針要求,這才是中國城市軌道交通信號系統的發展方向。

Commentary

Discussion on the Development Direction of Urban Rail Transit Signaling Systems in China

LIZhonghao

(Honorary Committee Member of China Association of Metros Expert and Academic Committee,Professor-level Senior Engineer)

China′s urban rail transit signaling systems possess the distinct advantage of later development.Nearly all existing metro lines adopt CBTC (communication-based train control) system and has achieved moving block except for few lines constructed in early 1990s,which is a long-awaited goal for several generations of rail transit signal professionals.Following the commissioning of Beijing Subway Yanfang Line FAO (fully automatic operation) train control system based on CBTC,numerous Chinese signaling system suppliers have independently developed their FAO products and completed engineering validation.The development of China urban rail transit signaling systems is now entering the ′unmanned (leadership)′ phase.The question of the future direction for China urban rail transit signaling systems must be addressed by ourselves independently.

When it comes to direction,it is essential to recognize the characteristics that set rail transit apart from other transportation modes.Regardless of the train speed level,departure density,or the number of compartments,there is only one track,making it the sole dedicated resource.Only centralized control can ensure that this sole dedicated resource operates at maximum efficiency while maintaining absolute safety.Consequently,railway inherits a semi-militarized management characteristic.Railway achieves centralized dispatching,command,and control of trains by adhering to train diagram,which serves as the link between transportation demand and transport capacity.

FAO (fully automatic operation) is the development direction for urban rail transit transportation.By implementing the automation of train operation entire process,manpower can be significantly saved,transportation efficiency enhanced,and transportation safety ensured.FAO greatly expands the architecture of the signaling system.Any disciplines related to train operation safety and efficiency,such as comprehensive monitoring systems,power supply systems,platform screen doors,and passenger guidance systems,can be categorized under FAO system.With a larger system,the probability of malfunctions increases.Considering the operational resilience of the FAO system and improving the efficiency of train operation under fault conditions,the ability to enable trains to operate autonomously in fault conditions becomes a developmental requirement.To achieve this goal,it is necessary to introduce the concept of ′fault-tolerant safe operation.′ The most significant feature of signaling system is ′fault-tolerant safety,′ which means ensuring the absolute safety of train operation under any circumstances.When adopting FAO system,the aspect of fault-tolerant safety changes to demanding the absolute safety of passengers,in addition to the absolute safety of train equipment.The introduction of fault-tolerant safe operation principles requires FAO systems with train autonomous operation capabilities to have active obstacle detection functions that meet safety integrity requirements.

FAO systems with train autonomous operation capabilities impose specific requirements on FAO system.It is essential to emphasize that:first,when the FAO system is functioning normally,it operates in fully automatic mode,without the necessity to grant train the autonomous operation capability; secondly,for low-medium capacity systems such as urban rapid rail,it is not necessary for all of them to adopt FAO systems with train autonomous operation capabilities.

The issuance of train diagram instructions conventionally involves communicating through pathway to ground equipment.The ground equipment then interlocks the sole dedicated track resource to establish a train safe operation entry routing,notifying the train to travel within a specified range at a given speed.In order to improve ground resource utilization rates,there is also the approach of issuing train diagram instructions directly to trains,letting trains request resources from the ground,and the ground resource can reduce interlocking units.Considering new interlocking conditions such as train-to-train communication,resource utilization rate can be improved,leading to enhanced transport efficiency.Some signaling suppliers incorrectly consider train-to-train communication as a signaling system,whereas it is simply a technical means.

Metro is the high-capacity transportation means primarily serving commuting flows,and the characteristics of peak hours are very prominent.From the perspective of shortening the operating intervals and reducing energy consumption,flexible train formation is essential for this transportation mode,and achieving dynamic flexible marshalling is advantageous for transport organization,a specific form of which is virtual coupling.Technically,implementing virtual coupling requires controlling the acceleration of trains and ensuring precise speed control to have crash-softening capabilities.However,engineering validation is needed for applying virtual coupling to transport organization,ensuring safety,and delivering benefits.

After the development of urban rail transit signaling systems in China has entered the era of unmanned operation,standardization of signaling systems becomes evidently crucial.In response,the China Association of Metros organizes the compilation of the CMTCS (China Metro Train Control System) general principles.These principles summarize the essential requirements of urban rail transit signaling systems,categorizing them into five types:CMTCS0 to CMTCS4.CMTCS0 has ATP (automatic train protection) functionality,CMTCS1 has ATO (automatic train operation) functionality,CMTCS2 has FAO functionality,CMTCS3 has train autonomous operation functionality under fault conditions,and CMTCS4 has dynamic flexible marshalling functionality.The demand for interoperability is considered a fundamental requirement of the CBTC system.There is no claim that one level is more advanced than another; instead,the focus is on applying the most suitable version.

As urban rail transit enters the era of networking,China′s rail transit construction is transitioning from a high-speed development stage to a high-quality construction stage.The economic and sustainable development requirements are especially emphasized.All transportation equipment must aim to meet transportation needs and fulfill the overall policy requirements of being safe,efficient,convenient,green,and economical,as outlined in the strategy for building a nation of transportation power.The development direction for China′s urban rail transit signaling systems is thus established.

(TranslatedbyZHANGLiman)