Design of a KSP wall is relatively straightforward and no different in essence to design of a conventional sheet pile retaining wall except that the wall stiffness and structural properties are reduced in proportion to the ratio of the length of the wall made up of kings. The reduced stiffness of a KSP wall typically has only a minimal effect on wall deflections.
KSP walls are designed for use with Z piles. U piles do not work efficiently in a non-continuous wall.
The simplest and most efficient form of KSP wall consists of pairs of crimped Z piles as kings, with pairs of the lightest practicable Z piles, as intermediates.
For more detailed guidance on the design and specification of a KSP wall, including options for water cut-offs, see the detailed Technical Guidance download below.
KSP walls are suitable for installation by pitch and drive method. This eliminates the problem of forward lean and reduces the need for alignment correction - making installation considerably faster. KSP walls can also be installed by silent pressing.
For further information and for guidance on other aspects of construction, see the detailed Technical Guidance download below.
Click here to download Technical Guidance on design and construction of a KSP wall.
May 2023: KSP walls are due to start shortly for slope stabilisation on both rail and highway applications, taking advantage of the important benefit that KSP facilitates groundwater flow.
2022: Saw completion of further KSP walls on the M1, M45 and M56 motorways.
31 August 2021: Correct Link to Technical Guidance Download reinstated (inadvertently re-directed in website upgrade of 28 July 2021).
July 2021: Installation of the last KSP wall on M4 Junctions 3 – 12 Smart Motorway marked completion of many kilometres of Smart Motorway KSP walls across the Highways England network. KSP walls are currently being designed for further schemes under the Smart Motorway Alliance programme.
2020 saw completion of substantial anchored and cantilever KSP walls for Langport Embankment for Network Rail, following on from those on Bridgewater rail embankment in 2019. KSP walls completed or in progress for Highways England include M23 J8-10, M1 J13-16, M4 J3-12, M25 EAs 01 & 06 and A19 Norton to Wynyard. Further KSP walls are envisaged on Highways England SMA schemes currently in the design phase.