The Freespan bridge (“Bridge 16”) is situated on Thesen Islands in Knysna. This is on the site of the former Thesen Sawmill, which has been developed into a large residential estate with a smaller commercial core. The original island was divided into nineteen smaller islands, which necessitated the construction of various bridges. Two of these formed part of a previous Steel Awards submission in 2006 where the project won the category for “Recycling and Sustainable Projects”.

The Freespan bridge completes the pedestrian link from the residential portion of the islands to the commercial area called Harbour Town and is a continuation of the route that crosses the two Monorail bridges. Due to the width of this particular canal, the difficulty (and cost) involved with piling and the sensitive nature of the site, the only viable option was steel. A suspension bridge with pylons on both sides of the canal was considered and discarded due to cost constraints and the impact it would have had on the views from the surrounding houses. This led us to the idea of a free-span bridge.

We decided on a tubular “spaceframe” structure to keep the size of individual members down, to minimise the visual impact and because we believed it would work well aesthetically.

To work out the design in order to span the required 46 meters, calculate the sizes and install the bridge were all challenges in their own right. The entire steel structure was erected in less than a day and the bridge had to be assembled from both sides of the canal.

People in residential areas are usually skeptical of structures that consist predominantly of steel, but everyone was pleasantly surprised by this bridge. The combined efforts of everyone involved resulted in a unique and visually appealing structure that blends in well with its surroundings.

The Dry Mill Phase 2 & 3 Sky Walks

Steel girder type “skywalks” providing horizontal movement between the North and
South second floor Penthouses was the design choice in the sectional title Phase 2 and 3 of the Dry Mill in an attempt to emphasize its historic steel character.

Steel stairs on either side of the 11-meter skywalks, supplemented by a lift on the Northern blocks, provide vertical movement from the undercover parking areas on grind floor.

Three skywalks in Phase 2, & One x skywalk in Phase 3 connect the ten luxury second-floor Penthouses. By connecting the North and South Blocks, the skywalks freed-up some vital floor area in the Southern Blocks as a Lift shaft, measuring 4,77m2 x 3 floors = 14.31 m2, was only required on the Northern Blocks.

• The western façade is protected from the southwesterly wind-driven rain by aluminium shop front type window frames with small openable windows.

• On the eastern façade, only the first portion of the skywalk structure is clad while the middle section is open with a 1 200mm high slatted handrail.

• These infill elements were positioned on the inside of the skywalks so that the structural steel girders are visible from the outside.
• The floor is constructed with Balau timber decking and the roof is clad with corrugated roof sheets to match the development and to retain the historic shed like the feel of the Dry Mill.

It was decided to paint all the steel elements of the skywalks and stairs with Red Oxide so that these structures are emphasised as a design element in the development where the design philosophy is to show as much of the historic structural components as possible. The Red colour successfully compliments the red De Hoop face brick payers used on the road surface below.

The Dry Mill history

The Dry Mill is one of the oldest industrial structures of the former Thesen Sawmill, originally used for storing and processing timber. Open crawl beam structures made out of goal-post type portal frames supported a center under-slung crawl beam system.

Special permission was given by the National Monuments Commission for the adapting and re-use of the building that have since won the CNBC International Property Awards for Best Re-development in South Africa and went through as a top 5 Finalist in the World.

Project Team – Dry Mill:

Developer Owner: Thesen Islands Development Company
Architect: CMAI Architects
Structural Engineer: LSM Structures & Civils
Quantity Surveyor: Steele Consulting
Project Manager: CMAI Architects
Main Contractor: Shamwari Projects
Steelwork Contractor: Prokon Services
Other: AM Aluminium (Glazing)

Project Team – Freespan bridge:
Developer Owner: Thesen Islands Development Company
Architect: CMAI Architects
Structural Engineer: LSM Structures & Civils
Quantity Surveyor: Steele Consulting
Main Contractor: Prokon Services
Steelwork Contractor: Prokon Services
Other: Lomot (Timber work)