The 71-year old China-North Korea Friendship Bridge connects North Korea's Sinuiju and Northeast China's Dandong, a border city in Liaoning Province, through which 70 percent of Sino-North Korean trade passes. Every day, cargo vessels from both sides make their way across the Yalu River.

However, in the past year, according to truck drivers, things have changed. "Since Jang Song-thaek was executed, many border trade companies have collapsed. Now the freight cars going to North Korea are obviously fewer than before," a longtime truck driver told the Global Times last week.

Jang Song-thaek, a deposed senior North Korean official, was executed in December 2013 for treason and driving the country's economy "into an uncontrollable catastrophe."

The traders have also become more wary while dealing with the counterparts on the other side. One cautionary saying among Chinese trade circles says you can trade with North Koreans but never invest. "There are too many cases where people's investment was completely wiped out. Now we demand payment before delivering the goods," said a driver surnamed Zhang.

A planned economy, political uncertainty and lack of reliable adjudication in disputes are all cited as reasons for investment in North Korea being high risk.

While waiting in line for customs to cross the bridge, Zhang received a call from the owner of the goods, who asked to cancel the shipment that day as he hadn't received payment from the North Korea side as scheduled. Zhang had to turn the truck around and drive back to the port customs storehouse. Such cases are frequent, Zhang says.

The much wider New Yalu River Bridge, built 8 kilometers downstream of the Friendship Bridge, was completed and set to be open in October last year. However, the bridge, paid for by China with an investment of 1.8 billion yuan ($288 million), remains closed due to North Korea's failure to build facilities on the other side.

The truck drivers all hope the bridge can open earlier as its capacity is much larger than the Friendship Bridge whose construction was started in 1937 and completed in 1943.