Security measures for the Expo 2010 Shanghai have so far been fully and successfully implemented, heightening the value of the experience for the future, a senior city police official said on Wednesday.

Cheng Jiulong, executive deputy director of the Shanghai municipal public security bureau, spoke on The Summertime Talk Show to answer caller questions on everything from traffic problems to Expo security to common complaints.

The bureau has made spokespeople from 11 functional departments and 12 district-level officials available to respond to public concerns and complaints online via Eastday.com and on air via Shanghai Radio.

The city has witnessed a 16-percent drop in crime year-on-year during the first half of the year, Cheng said.

The security situation in the Expo Garden turned out to be the main concern among tourists at the moment, Cheng said. To ensure safety at the event, a series of actions have been taken to deter a variety of crimes, he added.

As for complaints of long queues for the opening of the Expo Garden, Cheng explained that an excess of visitors seeking to enter the venue before its opening has contributed to backlog of visitors.

"Tourists could avoid trying to enter the Expo Garden in its peak period between 9 am and 9:30 am," Cheng suggested.

Security personnel in the Expo Garden, including 4,700 police officers and security volunteers, he said, have been assigned to rotating shifts, ready for any emergencies or accidents.

There are various police checkpoints and stations surrounding the Expo Garden where officers can help tourists solve their problems immediately.

To prevent crimes, more police have been deployed at key locations, including major airports, railway stations and bus stations for security screenings in 16 cities of the Yangtze River Delta region.

Traffic problems have been another major concern of residents during the Expo period, according to callers.

"Despite the fact that the number of vehicles passing in and out of the city has risen by 50 percent since the official opening of Expo 2010, the slowdown of traffic in the city has been under control thanks to our live monitoring system," Cheng said, while admitting that traffic jams had proven a key challenge.

As summer temperatures rise, car breakdowns and accidents should promptly be reported to police to reduce backups.

Chen added that in the event of an emergency, residents and visitors can call 110 in addition to local police stations, which now have operators taking calls 24 hours a day.

Cheng also cautioned Shanghai residents against incidents of telephone fraud, which are becoming increasingly common.