Swann Engineering Group has successfully delivered design, manufacturing and installation services for the Heathrow Towers, a dual-screened digital media development located in West London.
Situated along the elevated A312 carriageway, this latest Out-of-Home-Media project was undertaken by our team of engineers for renowned outdoor digital media specialists, Global, and complements their already extensive portfolio of roadside structures.
⬇️ Scroll down to see how we brought this OOHM project to life! ⬇️
Featuring a contemporary and minimalist aesthetic, the two 22-metre-tall standalone structures display digital media to pedestrians and road users on their way to and from Heathrow Airport.
Each structure has been carefully designed to accommodate two 5m x 8m portrait-orientated high-definition screens provided by Daktronics, which can be remotely programmed to display both static and dynamic digital media. This dual accessibility allows content to be viewed by road users travelling in both directions from the carriageway or pavement.
All design, fabrication, groundwork, detailing, and installation services were carried out and coordinated by our in-house project management resources.
Cultivating Design Innovation
As with all structural projects undertaken by Swann, careful design consideration was made at each development stage to ensure the structures can withstand the elemental forces they will be subjected to. Our design process is conducted in-house and overseen by our own chartered engineers, who review and ensure the validity of the proposed design.
Our internal review process verified that the towers will be structurally sound and provided an environment to cultivate innovation. It was during this phase that our team identified an opportunity to utilise and transform the stiffening fins of the structure into aesthetic design features.
We also designed and manufactured an additional steel grillage to support the structure during its transportation to the build site. This provided our ground team with greater logistical flexibility and enabled the structure to be transported to the site in prefabricated sections.
In addition to the grillage, we successfully designed a bespoke stillage that enabled the digital screens to be installed vertically into their steel frames. This increased the accessibility to the screens which allowed for greater efficiency when testing each of their electrical components and wiring.
With our decades of industry knowledge and extensive design capabilities, our in-house Technical Drawing team used 3D CAD software to generate digital proposals of all the components required for this project. Once approved by the client, these virtual concepts provided the blueprints for our highly skilled production team to bring to life.
Utilising Our Manufacturing Expertise
Taking place at our purpose-built manufacturing headquarters in Braintree, Essex, our experienced team of fabrication specialists began construction of the internal structural steel sections and the external screen frames.
Once assembled, pre-determined welds were subjected to (and passed) Non-Destructive-Testing, which is a method used on all our structures to assess the strength and quality of the welds.
Each tower required three sections of internal framework, which once manufactured, were demonstrated to the client during an onsite design review. We also showcased our holding down bolt solution to the client which was designed by our team of in-house engineers.
Once each section was fully assembled, it was sent to Wedge Group Galvanising’s Witham facility to be treated before being transported back to our Braintree headquarters for a trial assembly and screen testing.
Conducting a Trial Assembly
We always take great care in ensuring our structural solutions arrive at their install location ready to be deployed as efficiently as possible. With structures designed to accommodate digital screens, there is an added layer of complexity to ensure all the wiring, electrical components and screens are performing to their optimal level.
This means that for these types of projects we conduct a trial assembly of the structure with the digital screens installed and operational. This provides our own and third-party engineers with an opportunity to ensure that the structure meets the clients’ specification.
Once the trial assembly had been completed successfully, the structure was deconstructed into three separate sections which were then transported to the build location.
Putting in the Groundwork
The structures deployed for this project were split across two separate areas and labelled as the East and West towers, with a car park owned by the site provider identified as the build site. Both sites were set out using land surveying equipment and required our team to remove the existing surface-level asphalt before preparation work could begin on the foundations and piling.
Due to the structures having to be tall enough for the screens to reach above the elevated carriageway, extensive foundations were required to ensure that each structure was secure. This required our ground team to remove over 53m3 of earth for each of the foundation bases with nine Sectional Flight Auger (SFA) concrete piles per base.
With the bases dug, and the reinforced concrete piles installed, Circular Hollow Sections (CHS) of structural steel ducting was placed to accommodate the placement of power and data cables. A sand and cement screed was laid to the excavation formation with timber formwork constructed to the footprints base, which was secured and braced in preparation for the concrete pour.
With over three tonnes of steel reinforcement placed into the base of each tower, the bottom layer of steel was placed to the specification of our structural engineer’s design. A bespoke steel grillage with 48mm diameter holding down bolts was then placed onto the bottom steel reinforcement. A steel base plate template was secured to the shutters which was used to establish the line and level of the holding down bolts. The remainder of the top steel reinforcement was placed and inspected and signed off by the structural engineer.
Each base received over 42 tonnes of design mix concrete poured directly into the bases from the in-transit cement mixer lorry, with concrete cubes extracted after each pour for external testing. After a week, the 80mm steel base plate was placed onto the holding down bolts to confirm a satisfactory fit before the main steel assembly was delivered.
This entire process was then repeated for the opposing tower infrastructure.
Transportation and Installation of the Screens
Due to the size of the screen frames and load regulations on carriageways, the frames were designed to be transported in individual sections and in two separate loads.
Once delivered to the site, external cladding was fitted to both structures at ground level to minimise working at height. However, when required, our field team were able to utilise two lorry-mounted Mobile Elevating Work Platforms (MEWPS) to access the structures at height.
With the foundations prepared and the successful placement of the bottom section of the supporting structure, the screens for the West Tower were partially constructed at ground level and then lifted with a crane onto the supporting steelwork in two sections. The East Tower was fully assembled at ground level and successfully lifted onto the supporting structure in one seamless lift.
We were granted permission by TFL and Hillingdon Council to implement a single lane closure of the A312 carriageway during the lifting process, which took place at night to minimise the impact on road users.
With both sets of screens installed and the final cladding sections added, the electrical and data installation was implemented and tested successfully within the project timeline.
The Heathrow Towers were officially launched in September 2021 and working on this project alongside Global has been a privilege for Swann Engineering Group. It was made possible through the collaboration and coordination of many different parties and we would like to thank everybody involved for their outstanding efforts and commitment in what has been a fantastic project to be involved in.
Swann Engineering Groups Managing Director, Jeff Carlton, commented:
“I’m so very proud of the team here at Swann Engineering Group for their hard work and dedication in bringing this latest digital media site to life.
It takes incredible imagination, skill, persistence, coupled with long hours and hard work to develop an architect’s sketch into a fully functioning twin site like this.
A huge congratulations to everyone involved in this project, which complements our extensive portfolio of successfully managed and fully operational OOHM media developments”.
Click here to find out more information about this digital media superstructure, by reading Globals showpiece article.
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