With mobile vendors flooding back to streets in many cities, residents are noticing the return of nighttime vitality, but experts have called for more effective guidance to help street markets work well.

When mobile vendors occupied some streets in Dalian, Liaoning province, on Tuesday, they attracted enthusiastic visitors but also caused a traffic jam. After the night market finished, the area was littered with plastic bags, disposable paper bowls and other waste.

That led to the night market being closed for rectification, the organizers of the ongoing Dalian Shopping Festival told news website ThePaper.cn on Wednesday, adding that the spontaneous setting up of stalls by vendors without unified management had adversely affected the environment and traffic conditions.

"I'm really happy we have street markets again. It is part of our lives. But I hope they become more clean and tidy," said Dalian resident Jiang Lijuan, 65.

On June 1, when Dalian launched its first batch of street markets, it listed nine requirements, including that all commercial operators must remove garbage as soon as possible and keep the areas they operate in clean and tidy.

Similar measures to encourage street markets and the nighttime economy have been adopted in more than 20 other cities, including Chengdu in Sichuan province, Shanghai, and Nanjing in Jiangsu province.

Since March, Chengdu's city government has allowed people to run businesses in designated areas on some pedestrian streets in a move to boost the economy.

In past decades, street stalls were gradually banned in big cities because they were considered dirty and messy and affected the good image of a city. But this year's national civilized city evaluation index excluded roadside booths, street markets and mobile vendors from its assessment criteria.

Zhou Xueren, a researcher with the School of Economic and Social Development at Dongbei University of Finance and Economics, said urban managers should strengthen guidance and support.

"We need to reduce health and safety problems, ensure market order and provide supporting services for transportation and other coordination in order to maintain market vigor and the power of consumption on the one hand, while also meet requirements for safety, health and tidiness," Zhou said.

Street markets, which do not require much investment, can stimulate the independent employment of individuals, increase their income and bring new vitality to the recovery of local economies from the impact of the novel coronavirus outbreak, he said.

Traffic police in Shenyang, Liaoning province, said they will participate in the planning and setting up of roadside stalls to facilitate the activities of vendors and consumers and prevent traffic from being affected by stalls occupying roads.