Urban rail transit encompasses two primary systems: subway and light rail. In many major cities, both systems coexist, but what sets them apart?

Here, we'll delve into the distinctions between light rail and subway.

There are various misconceptions about the differences between light rail and subway. Some erroneously believe that rail transportation below ground constitutes a subway, while anything above ground is considered light rail.

Others suggest that light rail employs lighter steel rails, while subway systems utilize heavier ones. However, these distinctions are not entirely accurate—the primary differences lie elsewhere.

Both light rail and subway systems can be constructed underground, at ground level, or elevated on viaducts. While subway rails generally have greater weight than light rail tracks, both systems utilize heavy-duty steel rails to enhance track stability, reduce maintenance, expand the cross-section for passenger flow, and mitigate stray currents.

Differentiating between the two systems is primarily based on their capacity to handle maximum peak hourly traffic. Subways typically accommodate a one-way maximum peak hourly flow of 3-6 million passengers, while light rail systems cater to 1-3 million passengers.

Consequently, subway design incorporates features to handle higher passenger volumes. For instance, subway cars typically have axle weights exceeding 13 tons, whereas light rail cars weigh less than 13 tons.

Subway tracks generally have a plane curve radius of not less than 300 meters, whereas light rail tracks range from 100 to 200 meters. Subways typically operate with more train groupings and crew members than light rail systems.

The disparity in transportation capacity, vehicle design, and construction investment further delineates light rail from subways. Subways boast higher capacity, with a peak hour one-way transportation capacity ranging from 30,000 to 70,000 passengers, whereas light rail systems typically accommodate 6,000 to 20,000 passengers.

Consequently, subway trains comprise more groupings, ranging from 4 to 10 sets, while light rail trains consist of 2 to 4 sets. These differences in capacity influence axle weight, train length, and platform size, which is crucial for cost-effective construction and efficient passenger flow management.

The classification of rail transit lines into subway or light rail is based on train specifications.

According to international standards, urban rail transit trains are categorized into three models: A, B, and C, corresponding to train widths of 3 meters, 2.8 meters, and 2.6 meters, respectively.

Subway lines typically utilize A or B type trains, comprising 5 to 8 sets, while light rail lines employ C type trains, consisting of 2 to 4 sets. Train models and sets dictate axle weight and platform length, impacting construction costs and operational efficiency.

It's essential to note that the definition of a subway extends beyond underground tunnels. Instead, it encompasses high-capacity urban rail transit systems that utilize high-specification electric passenger trains to accommodate peak hour traffic ranging from 30,000 to 70,000 passengers.

Subways operate across various terrains, including underground, above ground, and elevated structures, providing a versatile solution for urban transportation needs.

In essence, while both light rail and subway systems serve as integral components of urban transit networks, their differences lie in capacity, design, and operational characteristics, each tailored to meet the unique demands of their respective urban environments.