On July 10th, at the track laying base of the No. 4 intermediate air shaft between Hengli and Panyu Square on Guangzhou Metro Line 18, workers slowly laid a 25 meter long track panel on the tunnel foundation, marking the official entry of the "fastest subway" under construction in China into the track laying stage.

(Construction site)

Set up 16 track laying bases along the entire line
The total length of Metro Line 18 is 61.3 kilometers, starting from Wanqingsha Hub in Nansha and ending at Tianhe Guangzhou East Station, passing through Nansha District, Panyu District, Haizhu District and Tianhe District, with 9 stations and 8 sections. Among them, 8 out of 9 stations are transfer stations, with the longest distance between stations reaching 25.9 kilometers. It is the section from Hengli to Panyu Square, which is currently the subway section with the largest distance between stations in China.

The entire subway line 18 needs to lay 122.6 kilometers of tracks. To ensure the smooth progress of the track laying operation, the construction unit steadily advances the construction while doing a good job in epidemic prevention and control.

The track laying construction plan includes 12 machine laying bases and 4 loose laying bases. The entire track laying project plan will invest in 32 mechanical equipment track cars, 64 subway specific flatbed cars, 24 gantry cranes, 94 track laying machines, 6 sets of welding equipment, etc. During the construction peak, more than 2200 people will work simultaneously.

As the track of Line 18, it is also "unique"
As a high-speed subway line with a speed of up to 160 kilometers per hour, unlike ordinary subway lines that use integral track beds, Line 18 of the subway is built according to the standards of high-speed rail, greatly improving the smoothness of the subway line and the comfort of passengers. At the same time, combined with the actual situation of the subway, three integrated track bed construction processes were comprehensively adopted, including steel spring floating slab prefabricated track bed, vibration damping pad prefabricated board, and double block sleeper. Among them, 1.23 kilometers of steel spring floating slab prefabricated track bed and 36.2 kilometers of vibration damping pad prefabricated track bed have been applied in schools, hospitals, residential areas and other areas. The application of steel spring floating slab prefabricated track bed in 160km/h rail transit is still the first time. The vibration damping pad prefabricated track bed is similar to the high-speed railway CRTS III slab ballastless track bed, with good vibration reduction effect, reducing the impact of train operation on environmental vibration and noise.

In addition, the vibration damping pad prefabricated slab track bed also needs to be filled with self compacting concrete during the laying process, just like high-speed railway construction. To ensure construction quality, subway builders carried out technological research and development. After up to 15 peeling tests, a series of data results such as the optimal mix ratio, performance parameters, and pouring process parameters of self compacting concrete were finally formed. They found a method to solve the difficult problems of strength differentiation, bubble retention, water seepage, track slab floating, and unsightly appearance of self compacting layer concrete. This not only effectively improved the overall quality of the track bed, but also achieved vibration reduction and noise reduction effects.

During the track laying construction, subway builders will also adopt the most advanced domestic high-speed rail CPII track control network precision measurement technology. The total station will cooperate with the track inspection car to comprehensively and systematically measure, analyze, and adjust the static geometric dimensions of the track. The measurement error will be controlled at the level of 1 millimeter, greatly reducing the "bumpy feeling" during train operation and improving passenger comfort. At the same time, smoothness is the core of construction, with emphasis on track alignment, reasonable adjustment of track geometry dimensions, and reduction of later operation and maintenance costs.
A 'high-level' subway track construction 'artifact'
In the track laying operation, subway builders will apply multiple new technologies. Introducing the most advanced self deformable wheel rail concrete construction vehicles, track laying cranes, and slab transport vehicles independently developed and produced by Anhui Xingyu Rail Equipment Co., Ltd. in the field of urban rail transit construction in China, the pouring of concrete in tunnels is relatively flexible and efficient, effectively improving material transportation efficiency while protecting tunnel segments. The application of new pure electric track tractors effectively reduces construction noise, reduces exhaust emissions, greatly improves energy utilization efficiency, and improves the working environment. We have invested in a new type of induction positive train for seamless rail welding and normalizing operations. Electromagnetic induction technology is used to heat the welding joints, overcoming the adverse factors of flame heating such as the state of the fire hole, gas quality, and gas flow rate. The heating quality is significantly improved, reducing the impact of human factors and comprehensively improving the quality of rail welding.

According to Guangzhou Metro Group, as of now, the civil engineering of Line 18 has been completed by 67%. Among the 9 stations, 1 has been capped, 7 are undergoing civil construction, and the remaining 1 is undergoing pre construction preparation; All 8 sections will undergo civil construction, including the entrance and exit lines of Longzhen Parking Lot, Wanqingsha Vehicle Depot, and Longzhen Parking Lot.