There will be a safe, convenient and efficient system of China-Europe direct cargo trains by 2020, the country's top economic planning body has said.It is estimated that there will be around 5,000 cargo trains running between China and Europe annually by 2020, according to a development plan issued by the National Development and Reform Commission As a key component of the Belt and Road initiative, direct cargo trains will connect a growing number of cities in China and Europe.Demand for rail cargo service between China and Europe has exploded in recent years because it offers an alternative to slower and riskier sea freight and much costlier air cargo.The development plan shows that the cargo train service system will consist of three routes -- an east route, a central route and a west route. The routes will not only connect China with Europe, but also with East Asia and Southeast Asia.Some 43 transport hubs will be created along the three routes and 43 railway lines will be built, according to the plan.There were 1,881 China-Europe cargo trains in service as of the end of June, which transported imports and exports worth 17 billion US dollars.The European Union has been China's largest trading partner for more than a decade, while China is one of the EU's biggest sources of imports. Bilateral trade amounted to 3.51 trillion US dollars in 2015.