Many of us may still remember, during the onslaught of super typhoon Mangkhut on Hong Kong in September 2018, a large wall-growing tree at Duddell Street in Central collapsed and damaged the adjacent declared monument over a century old – the Duddell Street Steps and Gas Lamps. After more than a year of hard work by the Antiquities and Monuments Office (AMO) of the Development Bureau (DEVB), together with the Highways Department and Towngas, the steps have now been restored to their previous appearance and the gas lamps have been relit. This time, I have invited my colleagues from the AMO to talk about the restoration process and challenges involved.

The exact construction year of the flight of granite steps at Duddell Street in Central cannot be ascertained. According to a series of old maps of Hong Kong and related archival materials, the steps were already there between 1875 and 1889. The four gas lamps at the top and bottom of the steps are two-light “Rochester” models made by the firm Suggs and Co. in the United Kingdom and were erected in the early twentieth century. Although originally lit manually, they now operate automatically. Since the electrification of street lights in Hong Kong, the four gas lamps have been the only surviving working examples of their type in the city.

Restoration with original materials and craftsmanship

On 16 September 2018, the steps and gas lamps were seriously damaged by the typhoon. On the following day, within two hours of the cancellation of the Tropical Cyclone Warning Signal No. 8, colleagues from the AMO arrived on the scene to conduct preliminary inspection and recording. At that time, the granite railings and their urn-shaped cement balusters on the left side of the steps were almost completely destroyed. Three of the four gas lamp posts had fallen, severely damaging their gas lanterns, and one of the cast-iron lamp posts was broken into pieces.

The Executive Secretary (Antiquities & Monuments) of the AMO, Ms Susanna SIU Lai-kuen, said that even though she had a heavy heart at that time, colleagues were determined to restore the monument using original materials and craftsmanship. They promptly collected, identified and recorded the scattered fragments of the monument and then sent them to the repository for detailed investigation and storage. In the afternoon of the same day, the AMO convened an inter-departmental meeting on-site. Apart from government departments, representatives of Towngas also attended the meeting to discuss the follow-up work.

Seeking assistance from the original gas lamp supplier

During the restoration process, AMO colleagues encountered various challenges. First, the gas lamps and steps had to be handled separately as different restoration techniques were involved. Second, as information about historical gas lamps and the craftsmanship required for their restoration were not available in Hong Kong, colleagues had to undertake a great deal of research and preparatory work. For example, they had to investigate the history and repair records of the gas lamps and steps, and also conducted various material analyses. I was delighted when, after much effort, the AMO finally managed to successfully contact the original gas lamp supplier in the United Kingdom. They then invited an expert from the supplier to Hong Kong in order to conduct a detailed inspection of the damaged gas lamps, and explore how they might be restored using the original craftsmanship and materials of a hundred years ago.

According to the Curator of the Historical Buildings Sub-unit of the AMO, Mr NG Chi-wo, after conducting a detailed inspection of the gas lamps in Hong Kong, the visiting British expert Mr Mark JONES brought them good news by advising that the three gas lanterns and one cast iron lamp post that had been broken into pieces could be restored. This was exciting news for the project team. In September last year, the AMO sent the parts of the gas lanterns and lamp post to the original supplier’s workshop in the United Kingdom for restoration. Meanwhile, AMO colleagues went to the United Kingdom three times to check on the restoration progress and exchange views with experts and engineers. The restoration process was also recorded.

Restoring the steps with the help of 3-dimensonal (3D) laser scanning

The restoration of the steps was no easier than that of the gas lamps. After the storm, more than 200 fragments of the steps were salvaged. Fortunately, AMO colleagues conducted a 3D scanning of the monument in early 2018 and collected a full set of survey data of the steps, providing important reference materials for the preparation of the restoration proposal. According to Mr NG Chi-wo, AMO colleagues recorded the damaged steps after the incident using 3D scanning. They also made 3D printout models of the stone fragments at a reduced scale and numbered them. A complete model of the steps was then assembled. Since the components of the steps were rather large, having this arrangement put in place meant that the restoration team only had to follow the numbers when assembling the components on site, making the restoration more efficient and accurate, and the construction time a lot shorter.

The urn-shaped cement balusters presented a different challenge during the restoration of the steps. Of more than a hundred urn-shaped cement balusters, 42 were crushed by the fallen tree. After investing a great deal of time and effort, the restoration team successfully reassembled 29 of the balusters, but it was impossible to restore the remaining 13 as they were too seriously damaged. The team then made copies of those 13, matching the original materials and style. In line with the international guidelines on heritage conservation, the numerals “2019” were marked on the bottom of the new urn-shaped balusters for the purpose of identification.

With all the hard work done by the AMO, the Highways Department, Towngas and various experts, the steps were reopened fully on the evening of 23 December last year with the four gas lamps relit. Here, I extend my special thanks to our colleagues at the AMO for having done so much to help conserve and restore Hong Kong’s monuments through their dedication and professionalism. If you ever walk past Duddell Street, why not take a close look at the monument and inspect the hard work of our colleagues?