Over the years, flooding of the Cogmans River has periodically devastated Ashton and the surrounding farmlands.
The floods of 1981 and 2003 caused major disruptions to local economic activities.
In January 1981, the well‑known Ashton canning factory was busy with its peak summer harvest when the factories were flooded between 1m and 2m deep. High‑water marks can be viewed in some buildings. It was recorded that nearly 50% of the wine grapes was lost that year.
Further downstream in the area of Van Loveren Wines, the river flow was reportedly more than a kilometre wide.
In 1937, the Cape government constructed two bridges over the Cogmans River on the Ashton Main Road at a cost of £5 600.
The bridge over the main channel was 100m long. It consisted of 5 earth‑filled concrete arches resting
on concrete piers and abutments. It had a roadway width of only 10 Cape feet (3.14m), with 2ft gravel
shoulders, allowing single‑lanetraffic only.
The second bridge crossed a second stream of the Cogmans River about 50m to the west. It was a single span bridge only 8m long, but was 5.7m wide to match the adjoining road width.
To allow two‑way traffic, the narrow main bridge was widened to 10.3m in 1951 at a cost of £10 800. The piers were widened to support additional concrete arched walls.
Cantilever beams were added to form the wider bridge deck. The second bridge was buried under the
upgraded road approaches, because by that time, the river had converged into one main stream.
The new Ashton Arch, consisting of 4 traffic lanes and 2 pedestrian pathways, completely replaced the
old bridges. It is wider, longer, and higher than its predecessors, promising better flood resilience and a long service life.
Construction of the Ashton Arch
The new Ashton Arch is a tied‑arch bridge. The roadway deck is carried by steel hanger cables suspended from the two reinforced concrete arches, while each arch is anchored by a horizontal tie‑beam (located between the road lanes and the pedestrian paths). Since the bridge is self anchored
with its forces in balance, it allowed the bridge to be constructed in a temporary position adjacent to the road and then moved transversely into its final position. This ensured minimal disruption to traffic during
the bridge construction.
A key improvement of the new bridgeis the absence of supports in the river. Due to the arch form, the new bridge has a single span of 110m, which significantly improves the hydraulic performance when compared with the previous four large piers that supported the historic bridge.
The Ashton Arch has a design life of 100 years and will be able to withstand a 1‑in‑200‑year flood without overtopping. It has become a landmark of Ashton, complementing the scenic route and paying homage to the road’s history by preserving the arch bridge form.
