Spiderman helps

A few days ago the city of Hangzhou, which is the capital of Zhejiang province and is located a bit south of Shanghai, launched a particular project.
The city has a major problem with its sewer system. The covers of the manholes, which give access tot the sewers, get stolen in order to sell the metal. Citizens of Hangzhou keep in falling in those manholes, renamed as "deathtraps".
So the city developed a plan of installing spiderwebs which can cover the hole and can hold the weight of an adult person.
Hope it works!