A team of rope access specialists and engineers will start work to stabilise La Coupée on Monday after the structure was damaged by rockfall.
Part of the wall along the isthmus collapsed earlier this month.
Damage was also caused by rockfall in the same area to the southern end on the western side of the crossing.
A civil engineer from Geomarine in Guernsey and a geological engineer from the firm's Jersey arm rushed to Sark on Thursday to assess the damage.
They've already been planning the remedial work which is expected to take until next Friday to complete.
The materials and equipment needed to do the work are being shipped into Sark from Guernsey, Jersey and the UK. It should all arrive before or on Monday so a five-man team of rope access specialists can start work alongside the engineers to stabilise the wall area and adjacent cliff face.
They'll be using reinforced concrete and anchor pins to shore it up.
La Coupée is already closed to "all but the most essential vehicle traffic" - with "weights to be kept to an absolute minimum" - but from Monday the crossing will be closed to all traffic.
The current partial closure and next week's full closure are "for the safety of all and a precaution against further damage" said a spokesperson for the Douzaine, which is a committee of Chief Pleas, Sark's government.
The Douzaine said it wanted to thank Geomarine, Isle of Sark Shipping, Kevin Adams, and Shaun Southern for their "swift response and assistance".
Pictured: La Coupée was damaged by rockfall last January too.
The recent damage is not the only time that a rockfall has caused fears over the safety and long term future of La Coupée.
The isthmus connects Sark and Little Sark and is the only way to get between the two except for by boat.
Made up of sedimentary rock, it has had handrails since the early 1900s, and the current handrails were put in place by German prisoners of war after Sark's liberation in 1945.
While minor rockfalls may be common from cliff faces, last January saw a 'large chunk' fall from La Coupée.
At the time, the Seigneur described it as being around 1000tonne.
Christopher Beaumont called for a survey of the iconic walkway to be carried out then, believing the damage then had been caused by coastal erosion following a period of wet weather.
Express has asked Chief Pleas if this was done, or when the last survey was carried out.
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La Coupée closed after rockfall
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