Hampstead Road & PSB Building
HS2 and Costain Skanska JV
58 weeks
£NDA
Camden, London
Location & Overview
Having already carried out works across the HS2 site with a value of over £30m, this particular area was situated on the busy Hampstead Road, directly adjacent to Euston Train Station, within 15m of LUL Northern Line running tunnels. Close by was a former LUL site that contained a vent shaft to the Northern Line tunnels that were visible at basement level.
Work, Challenges & Solutions
Enabling work, involving Asbestos removal under fully controlled conditions, soft strip of all buildings, including service isolations and disconnections, including a UKPN substation.
Demolition of a petrol station, 2 abnormally high 4 & 6 storey warehouses and the Power Signal Building for Euston, which contained a SCARDA cable controlling all rail tracks into and out of Euston Station.
The Network Rail specification required crane and lifting equipment to be de-rated, and no open-face methodology was permitted.
Two of the warehouses shared a basement; therefore, a combined demolition scheme for both was designed. Due to the capacity of the basement walls, one did not require basement propping, whilst the second used a combination of raking steel props based on the slab and a mass filled berm.
Basement works were simplified by the clever use of demolition-generated materials, and a sequenced method of slab removal to maintain the stability of the neighbouring roads and buildings.
To accommodate future piling, the basement was cleared of obstructions, including the raft foundation and all temporary works, for which a 75-tonne machine was used to break the slab due to its thickness.
The project involved land remediation to one of the buildings, obstruction and pile cap removal, land preparation and pile mat design.
Utilising a large crawler crane to service the buildings with occasional supplementary visits with a mobile crane, as well as using large lifting bins for metal clearances and reducing machine times for moving debris across the floor slabs, all expediated the programme.
We designed a bespoke methodology to minimise noise and disruption due to the neighbouring properties being occupied by our client, Network Rail, i.e larger plant was utilised for hydraulic processing to reduce percussive methods.
Achievements
The PSB building used shipping containers as a demolition protection screen to protect both rail assets and operatives. This was the first time this method had ever been used.
98% of waste resulting from the project was diverted away from landfill.
Innovative use of 35,000 tonnes of demolition arisings crushed on site to replace a temporary propping solution, reduced transport journeys by 1,200 as well as costs and subsequent emissions to the environment.
Successful delivery of the project required an innovative design of propping, sequencing, and load balancing to maintain overburden pressure on the tunnels and provide support to the basement walls during the demolition of the ground floor and raft slabs.
The project team were given the Construction News Project of the Year by a Specialist Contractor Over £5m Award.