Shanghai has intensified security measures along its major railway routes for the upcoming Expo, the local authority said Thursday.

Two headquarters and many checkpoints have been set up, connecting various regions, such as Nanjing, capital of Jiangsu Province, and Hangzhou, capital of Zhejiang Province, in three rings considered as the railway security front lines, said Fan Fuming, director with the Public Security Bureau of Shanghai Railway.

The move, along with previous security inspection measures, is expected to further block "suspicious people or goods" from entering the city during the Shanghai World Expo, which will run from May 1 to Oct. 31, he said.

Shanghai railway system has mobilized people from neighboring regions this year to reinforce the security campaign for the upcoming event.

More than 28 million people are estimated to visit Shanghai during the event via rail routes. Shanghai's rail network comprises more than 110 passenger stations and some 100 cargo stations.