# Transportation Deployment Casebook/2024/Suzhou Metro
## Overview
### What is Metro?

A metro is a train system that runs underground or above ground in big cities to help people move around fast.

### Background: Suzhou City and Its Metro

Suzhou, a Chinese city housing 10 million residents, ranks as a significant metropolis. Over the past half-century, the city has seen remarkable growth, transforming from a town with limited touristic appeal to a global award winner in urban planning.
Suzhou stands as a major industrial hub, holding the second-highest count of factories in China, including those manufacturing iron, steel, textiles, electronics, and computers.
The city’s robust growth has also fueled the service sector, with tourism being a notable contributor, adding 150,000 Yuan to the city’s revenues in 2013.
Due to its proximity to Shanghai, a city with a rising demand for premium services, Suzhou has turned into a magnet for foreign investment. Public transportation, epitomized by the Suzhou Metro, is a critical component of these services.
The inception of the Suzhou Metro occurred in 2007 when the local government decided to address the transportation needs of its citizens, leading to the metro’s construction.
The operational lines of Suzhou Metro, namely lines 1, 2, and 4, were initiated in 2007, 2009, and 2010 respectively, becoming fully functional in 2012, 2013, and 2017. At present, these lines traverse a cumulative 120 kilometers across their 93 stations. There are prospective plans to double this coverage to 240 kilometers by the end of the decade.

## Qualitative Analysis
### Historical Background of Suzhou Metro System
#### Overall development

In 1996, Suzhou City began to study the construction of rail transit [1].
On December 28, 2003, the foundation of the Jinji Lake test section project of Suzhou Rail Transit Line 1 was laid, which was the first rail transit project in Suzhou [2].
On December 26, 2007, the construction of Suzhou Rail Transit Line 1 started [3].
On April 2, 2008, the logo of Suzhou Rail Transit was determined [4].
On December 25, 2009, the construction of Suzhou Rail Transit Line 2 started [5].
On January 12, 2012, Suzhou Rail Transit Line 1 began trial operation [6]. On April 28, Suzhou Rail Transit Line 1 opened for trial operation [7]. On September 27, the construction of Suzhou Rail Transit Line 2 extension, Suzhou Rail Transit Line 4 and branch line started [8].
On December 28, 2013, Suzhou Rail Transit Line 2 opened for trial operation [5].
On December 16, 2014, the construction of Suzhou Rail Transit Line 3 started [9].
On June 28, 2016, the construction of Suzhou Rail Transit Line 5 started [10]. On September 24, Suzhou Rail Transit Line 2 extension opened for trial operation [11]. On December 7, Suzhou Rail Transit Line 4 and branch line began trial operation [12].
On April 15, 2017, Suzhou Rail Transit Line 4 and branch line opened for trial operation [13].
On November 27, 2018, the construction of Suzhou Rail Transit Line 6 and Suzhou Rail Transit S1 Line started [14].
On August 18, 2019, Suzhou Rail Transit Line 3 began trial operation [15]. On September 30, the construction of Suzhou Rail Transit Line 8 started [16]. On December 25, Suzhou Rail Transit Line 3 opened for initial operation, and Suzhou Rail Transit Line 7 started construction [17].
On February 7, 2021, Suzhou Rail Transit Line 5 began trial operation. On June 29, Suzhou Rail Transit Line 5 opened for initial operation.
On May 6, 2022, the construction of Suzhou Rail Transit Line 2 extension, Suzhou Rail Transit Line 4 extension, and Suzhou Rail Transit Line 7 extension started. From November 11, Suzhou Rail Transit Line 5 opened the cab, becoming the first fully automatic operation line in Jiangsu Province to open the cab. In December, Suzhou Rail Transit Group Co., Ltd. held a special consultation and demonstration meeting, suggesting that the "S1 Line" be renamed as "Line 11".

### Technology
#### Signal System

Suzhou Metro employs the Fourth Generation FAO Signal System, commonly known as the unmanned driving system. Compared to the third-generation system, the fourth-generation system offers higher automation and reliability. It enables automatic train operation, automatic stopping, passenger embarkation and disembarkation detection, and automatic departure. Additionally, a failure in a single system module does not impact the overall system operation.
Suzhou Metro utilizes an advanced train control system provided by Siemens, known as the Train Guard MT Communication Based Train Control (CBTC) system, along with a free propagation radio WLAN system, Sicas ECC electronic interlocking system, and AzS axle counters for its signaling and communications. This setup ensures efficient and safe operation of the metro lines​​ [18].

#### Typical Cases

As part of Suzhou Metro Line 6, Hanqingqiao Station is considered a pioneer in digital transformation. It has introduced a range of intelligent passenger service equipment, including smart service terminals, dual-eye fare gates, intelligent customer service robots, and smart guidance screens. These devices enhance passenger convenience and intelligence during their journeys [19]. Including:
* Smart Service Terminals: Passengers can directly voice their needs for ticket purchase, recharge, and issuing exit tickets at these terminals, which will automatically execute the corresponding actions.
* Dual-Eye Fare Gates: Using visual technology, these gates make logical judgments for passage and intelligent person recognition, improving safety and reliability.
* Smart Guidance Screens: Combining electronic media with traditional directional lightboxes, these screens display operational information within the station and enhance station management flexibility.

### Policy in Birthing Phase

Policies have played an important role in the birthing phase of the Suzhou Metro, providing guidance for its expansion and operation. Government approvals and support were critical to initiate the construction phase and expand the network. For example, construction of Line 1 began in 2007 and was put into operation in 2012. This was followed by the construction of Lines 2 and 3, each with specific timelines and targets, thus connecting districts and increasing mobility in the city. The government has also introduced a succession of fare and ticketing policies, including discounts and other benefits for users.

### Market Development

Suzhou rail transit has been in operation for 10 years, and has opened and operated 5 lines with a total mileage of 210 kilometers, transporting more than 2.2 billion passengers.
The 5 rail transit lines that have been opened in Suzhou cover an area of about 336 square kilometers and a population of 2,754,500 people in Suzhou. The average daily passenger flow has grown from 100,000 to 1,200,000, with the highest reaching 1,910,000 in a single day, and the proportion of rail transit in public transportation travel has exceeded 50%.
In 2022, Suzhou Rail Transit Group completed engineering investment of 20.5 billion yuan, exceeding the annual plan by 5%.
Among them, Line 6 completed an annual investment of 7.08 billion yuan, Lines 7 and 8 completed a total annual investment of 7.85 billion yuan, Line 11 completed an annual investment of 5.31 billion yuan, and the project of extending Lines 2, 4 and 7 completed an investment of 253 million yuan.

## Quantitative Analysis
### Data Collection and Methodology

The life cycle can be modelled by an S-curve which is used to display data over some time. S-curves (status vs. time) allow us to determine the periods of birthing, growth, and maturity. Here, it is assumed that the data used for modelling takes on a logistic shape to seek a curve that best fits the data.
In the current context, to analyze the life cycle of Suzhou Metro, the operated kilometers by Suzhou Metro are considered as the status and the consequent years as time to plot the S-curve. The required data was then collected from the annual reports published by Suzhou Rail Transit over the years from 2012 to 2022.
The life-cycle model of Suzhou Metro can be represented using the following equation:
S(t) = Smax/[1+exp(-b(t-ti)]
Where:
* S(t) is the status measure, (Passenger-km traveled).
* t is time (usually in years).
* ti is the inflection time (year in which 1/2 Smax is achieved).
* Smax is saturation status level. In this model, I used the maximum passenger volume.
* b is a coefficient to be estimated.
I fit the data using least squares to estimate the values of b and ti.

### Results and Interpretations

To plot the S-curve and the forecasted model, I obtained the data from Suzhou Rail Transit 2022 Social Responsibility Report which was published by Suzhou Rail Transit Group Co Ltd.
Suzhou Metro :
| Time | Passenger volume (10,000 visits) | Predicted passenger volume (10,000 visits) |
| 2012 | 2594.8 | 2104.92 |
| 2013 | 4875.4 | 4260.28 |
| 2014 | 11626.8 | 8053.67 |
| 2015 | 13633 | 13640.56 |
| 2016 | 14850.7 | 20033.11 |
| 2017 | 24569.6 | 25538.47 |
| 2018 | 32414 | 29233.98 |
| 2019 | 36168 | 31318.61 |
| 2020 | 30456.3 | 32380.75 |
| 2021 | 40300 | 32893.89 |
| 2022 | 33344 | 33135.43 |
The parameters and the model derived from the regression analysis on the above data are as follows:
* Final Market Size (S$_{max}$) = 33344.
* Slope (b) = 0.777.
* Inflection Time (t$_i$) = 2015.47.
* R$^2$ = 0.924.

## References

* Suggestions on adjusting the unbuilt lines of urban light rail. Suzhou, China. 2009-04-14.
* The foundation stone of the test section of rail transit line 1 was laid. Suzhou Industrial Park News Center.
* Groundbreaking for Rail Transit Line 1. Suzhou Industrial Park News Center.
* Suzhou rail transit logo out. Suzhou Municipal People's Government. 2010-11-19.
* Cross traffic string of Suzhou City, Line 2 to come. Suzhou Industrial Park News Center. 2013-11-20.
* Suzhou Rail Transit Line 1 first full line test run on January 12. Suzhou Industrial Park News Center. 2012-01-13
* Suzhou became China's first prefecture-level city to open rail transit. Chinese government network. 2012-04-28
* Railway Line 4 and Branch Line 2 Extension Started. Suzhou Industrial Park News Center．2012-09-28
* Line 3 officially started "well" shaped line network landing. Suzhou rail transportation. 2014-12-17
* Vice Mayor Lu Liusheng presided over the mobilization meeting for the start of Line 5. Suzhou Railway Transportation. 2016-06-29
* Suzhou rail transit line 2 extension officially opened. Suzhou Railway Transportation. 2016-09-24
* 480,000 people experience "taste" line 4. Suzhou Railway Transportation. 2017-04-01
* Line 4 and the branch line on April 15, 6:00 opening trial operation of the ancient city of a thousand years to open the north and south "artery". Suzhou rail transit. 2017-04-14
* Suzhou rail transit line 6, S1 line started construction. Suzhou rail transit．2018-11-27
* Line 3 starts test run with no load. Suzhou Railway Transportation．2019-08-18
* Suzhou rail transit line 8 started construction. Suzhou rail transit．2019-09-30
* Suzhou rail transit line 7 starts construction, line 3 opens for operation. Suzhou rail transit．2019-12-25
* Technology iteration for smarter, low-carbon subway operations. https://www.sohu.com/a/638289397_121388342
* Unveiling the "smartest" station of Suzhou rail transit. https://new.qq.com/rain/a/20231019A032IS00