Report No. : GEO Report No. 116
Report Title : Review of Effective Methods of Integrating Man-made Slopes and Retaining Walls (Particularly for Roadside Slopes) into Their Surroundings (2001), 212 p.
Author : Halcrow China Ltd.
Hong Kong has a large number of man-made slopes, which form an increasingly visible element in the landscape. In recent years media attention has been directed at the visual appearance of man-made slopes. As a result, GEO commissioned a study (Agreement No. 9/98) to provide guidance on methods of integrating slopes into their surroundings.
The objective of the study was to produce guidelines to reduce the visual impact of slopes to enable them to be integrated into their surroundings. This was to be achieved by incorporating accepted good landscape practice into the findings of a review of local and international practice into methods of reducing the visual impact of slopes. The local review incorporated current design practice, inspection of some 200 slopes, and surveys and interviews with the industry. The international review comprised a literature review of slope landscape techniques used to reduce visual impact elsewhere in the world, that might be applicable to Hong Kong.
This report is set up as a guidance document taking the reader through the various stages of the design process. This includes a substantial section on the different slope landscape treatment methods used in Hong Kong. This is accompanied by tables that provide an evaluation of a wide range of slope treatment techniques.
The landscape treatments reviewed are based on the treatments identified from the inspection of local slopes and information on proprietary products provided by the manufacturers or their agents. Altogether, about 50 treatments are included, which are grouped by treatment type, namely soft, hard and mixed. For each type, applications and considerations on their use are presented. The individual treatment types are evaluated based on the findings of the inspections.
The main conclusions based on the findings of the study are as follows:
- Feedback received from engineers indicates that the existing landscape guidance is considered insufficient.
- Landscape objectives are not clearly stated in the design process, providing no mechanism against which to verify the finished landscaping product.
- A large number of treatments are available in Hong Kong but only a few are used in practice.
- From the inspections, sprayed concrete was found on 50% of the slopes inspected.
- Several alternative treatments for vegetating steep soil slopes exist and should be trialled in Hong Kong.
- Improvement in landscape treatment was noted on slopes completed in the last few years.
The report is in 2 volumes. This is Volume 1 and is the guidance document. Volume 2 contains the results of some 200 slope inspections carried out during the course of the local review. The guidance is intended for use by geotechnical engineers, and is not meant to be a complete coverage of aesthetic slope design. Emphasis is placed on subject matter that is particular to Hong Kong.