In collaboration with The Conservancy Association Centre for Heritage (CACHe), a local organisation that advocates social awareness of heritage conservation, “Manhole Covers Exhibition” at Nan Fung Place showcases a selection of the city’s manhole covers to encourage the public to discover the history and industrial story of Hong Kong from one of the most common, yet rarely examined, aspects of the urban landscape.

Visitors will be able to learn more about Hong Kong’s urban development by interpreting the information on the manhole covers and discover how the city developed through different kinds of infrastructure. The idea is to stimulate the effective use of natural resources and provoke discussions on how urban design in the future can be improved and integrated into our daily lives.

To enable workers to easily identify the functions of each manhole cover, they all bear different patterns and codes that identify different government departments, drainage contractors, manufacturers, and loading capacity. The varied colors, shapes, and symbols on the covers are all designed with specific meanings.

For example, the square cast iron manhole covers named “Big Belly Button” were designed in two patterns and commonly used during the 1950 and 60s. According to a “round for rainwater, square for sewer” theory developed by industry insiders in the past, the public can observe the usage of the covers simply by looking at their patterns. The round and radical pattern indicates the cover is for a stormwater drain, while the small square pattern indicates the cover is for a sewer.

Before the 1990s, manhole covers engraved with the symbol “F↑H” were not just for Fire Hydrants, the arrow in the middle, known as a “Chicken Foot Mark”, meant it had been directly purchased by the Government Supplies Management Division before changing to public contractors in the late 1990s.

To improve garbage filtration and drainage efficiency, gully gratings with diagonal slots used to be equipped together with overflow weirs known as “stool chairs” and gully traps which are also commonly called “curry tanks”, to provide safer road conditions and a more convenient city life for us all. Due to the heavyweight of cast iron manhole covers, some of the original designs and materials are no longer in use and have been gradually replaced by more expensive stainless-steel covers to increase overall efficiency. These are just one example of how advances in technology have affected the development of the local cast iron industry over years.

The exhibition includes topics like, “Decoding Manhole Covers” and “The Emergence of Cast Iron Manhole Covers”. Manhole covers from around Sheung Wan are showcased at the exhibition with detailed notes that enable visitors to distinguish the types and characteristics of manhole covers. It also introduces local foundries and craftsmen as well as the manufacturing process of manhole covers.