Quay on the River IJssel, Doesburg
which no foundations may be built and no trees may
be planted. Where steps break into the line of this
wall, continuous piling has to be undertaken.
The wall that bridges the difference in height
between the high and low quays is intended to be
a real river wall, and should not evoke associations
with a fortress. This explains why it has been built
at a slight slope, why it is finished with grey vertical
stripes, and also why it is topped not with a balus-
trade but with railings.
Inclined at an angle of 2.6:1, the quay wall consists
of a piled retaining wall with two slopes of post-
stressed elements. The underlying construction
consists of piles driven into the riverbed at 70cm
intervals, precisely between the anchors for the
sheet-piling. To construct the retaining wall, a slab
was cast onto the top of the piles.
Due to their shape, the elements – which are 4.5m
high and 2m wide, with a projecting upper edge
and a toe slab on the underside – were constructed
on their sides. Post-stressed on site with 12.9mm-
diameter FeP 1860 strands, they abut each other
without any bonding material.
The quay wall has been faced in a random bond
created with grey prefabricated strips in three differ-
ent lengths, but with a consistent width of 20cms.
These have been applied up to the level of the edge
of the quay, which projects slightly. As the wall is
subjected to such extreme conditions, the only
option for creating the desired finish lay in bonding
the strips to the wall. To ensure that they would not
detach when submerged, atmospheric humidity
had to lie below 70 per cent. In northern Europe,
this situation can pertain only in daytime during the
summer. The pace at which work could proceed
was thus determined both by this and by the risk of
high water levels in the river.Designed by OKRA, the strips have a structured sur-
face evocative of ‘solidified water’. They are made
of epoxy concrete sandblasted in the factory, but
do not have an anti-graffiti coating, as this would
affect the structure of the wall. Any graffiti will be
removed by sandblasting.The finish of the curving wall of the quay is accen-
tuated by vertical lines: as you walk along the quay,
the number of strips rises. These have been applied
in a vertical pattern, an effect that is accentuated by
narrow vertical joints and broad edge joints.The refinement of the wall gives expression to its
height relative to the fluctuating water levels. White
slabs are a poetic expression of the high water;
irregular stripes create a graphic representing the
extremely high water levels of 1995.