When a direct freight train line between China and Europe launched in March 2011, many believed it wouldn't last longer than a few years. 

The 8,000 km trip followed a complicated route that snaked through Kazakhstan's mountains and Russia's prairies. It was far more expensive than long-established ocean freight services that had become the industry standard. 

But 10 years on, the railway is now a desired way for companies to move goods between two of the world's biggest economies. 

A handful of departures in 2011 have become more than 40 in 2021. In fact, the COVID-19 pandemic has had little effect on the frequency of service and more trains are likely to be added in the next year.

"This train has proved how vigorously it [the rail service] can step up, how efficient it is and how quickly it is able to work through weak moments," said Bernt Puten, who manages a cargo company that receives Chinese rail freight in Germany. 

READ MORE:

AstraZeneca jab 'safe,' clot fears remain
 

Hackers leak fake polish radioactive threat
 

Secrets of 'world's first computer' revealed
 

Billions of dollars in subsidies from Beijing have improved travel time along the route, which now averages between 14 and 16 days.

Most of the trains make their first European stop in Duisburg, Germany, an industrial city along the Rhine river, which has become the continent's largest inland port. From there, goods are put on barges, trucks, or other trains and taken to all corners of Europe. 

The growing demand for rail shipments coincides with European trade with China reaching record levels in 2020.

Exports of EU goods increased by 2.2 percent and imports rose 5.6 percent.

China is now the bloc's biggest trading partner and ports such as Duisburg have become key logistics hubs to exchange goods. 

Electronics, toys, and automobile parts are some of the most common imports to Europe that are shipped using the rail service. 

Chinese imports exceed the volume of European exports, which consist of mostly high-end goods such as wine and textiles. 

For every two full containers arriving in Europe from China, only one heads back the other way and the port only earns a fifth of the fee from empty containers that have to be sent back to China.

Port officials say the ratio of imports to exports is improving. 

Beyond shipping containers, many say the train has created a special economic link between China and Duisburg. 

The city's mayor, Soren Link, has called Duisburg "Germany's China city" – and in 2016, China's President Xi Jinping visited the city during his state visit to Germany. 

Telecommunication giants, engineering firms and chemical companies from China have launched or relocated their European headquarters to the region. 

"In the future, this rail connection can also help to get even more out of our economic opportunities. There are a number of industries here that are very excited to do so," said Felix Neugart of the NRW Trade and investment agency.

But a worldwide shortage of empty containers threatens to stunt the pace of growth.

Shipping costs between China and Europe have quadrupled since the end of last year.