海角视频

Sun, sun, sun. Our initial trips to Liverpool’s Bramley-Moore Dock for project design workshops were all characterised by idyllic, hot, sunny days, and that happened all the way from the first spring right through the year.

The blue skies provided a wonderful backdrop and welcome to the city of Liverpool. Surprising? Maybe. Certainly notable at the time and memorable looking back. But I also remember walking back into the city from site on one of those balmy evenings, heading away from Regent Road (the main road to the east of the site) and turning to the walkway along the River Mersey, and feeling a change in the air. Let鈥檚 call it a 鈥榖reeze鈥�.

The need for wind studies to be part of the design had been known to us from the start of the project. We have extensive previous experience of wind comfort and safety issues from other stadia projects, like Aviva Stadium in Dublin and London 2012 Olympic Stadium (where we also looked at wind speeds in the track and field area 鈥� both for athlete comfort and to help limit speeds for validity of records).

For The People鈥檚 Project, our wind studies would be the most extensive and comprehensive we鈥檇 ever undertaken for a stadium. Moreover they were part of a wider 海角视频 design that addressed comfort, safety and atmosphere for spectators arriving, using and leaving the stadium for this most idiosyncratic and challenging, but unique and amazing site. This blog presents our design journey of this part of the project.

The challenge of Bramley-Moore Dock

The stadium site would be on a newly filled dock platform, with retained water in Nelson Dock to the south, the Half-Tide Dock and utilities building to the north and the River Mersey to the west. These constraints meant access for 54,888 spectators and vehicles could only be from the west side. But that 鈥榖reeze鈥� that I felt stepping out onto the waterfront was representative of the site-winds from the west, which could be strong.

Placing a large stadium into a windy area influences the wind regime. The free flowing wind has to 鈥榞o somewhere鈥� and, on impact, the obstruction of the building either causes it to move over the top of the building, or it can move down to ground in a downdraught, creating more wind at low level.

After these initial disturbances to the free flow, the wind moves around the sides of the building and can then build up to high values at the corners, where it will be able to sweep around the stadium. We found the north-west and north-east areas would be crucial for the stadium, and that the wind could still be strong along north and south sides before starting to dissipate.

A data-driven approach to wind engineering

Our approach to the wind engineering for the new stadium was thorough and considered. We gathered the wind data, defined a site climate regime, established the building effects through modelling, considered the differing impacts and from this developed our design solutions.

We’d undertaken some conceptual computational fluid dynamics (CFD) modelling and desk-study thinking, but the first tranche of engineering modelling was through wind tunnel testing with specialist tunnel testing experts, RWDI. This is a very tangible process, in which the real scale of the building in the surrounds is visible.

Smoke plumes in the test tunnel can be used to show the direction, movement and intensity of wind flow. We modelled a series of configurations: the existing site (at the time before work started), the future with the stadium, and the future with the stadium and other potential developments. It didn鈥檛 surprise us too much that the findings showed that an unmitigated stadium design would show locations of strong 鈥榮peed-up鈥� of wind that would not conform to usual compliance criteria.

The process would ordinarily move straight into mitigation designs and to an extent it did, but there was also an intense period of challenge and reflection. The design task that was clearly presented ahead of us made us all scrutinise the criteria and findings. The results showed that the existing site was not an entirely happy working environment under wind, and that visiting spectators would need to be protected against potential strong winds. Questions were asked: 鈥淲hat does this wind speed really mean?鈥�

Wearing goggles and holding onto a barrier, we stood on a platform in the wind tunnel with the speed increasing towards representative values. This very real experience helped the team appreciate that strong wind was not to be taken lightly. Our extensive wind engineering experience meant we supported the long-standing criteria and results, and that we could bring other members of the project team into these vital conversations to share and develop our final approach.

Working together to develop mitigation measures

We fully appreciated that any wind mitigation measures could have potential to disrupt the proposed design. Because of this, we set-out clear philosophies for a direction of travel:

• Provide a safe microclimate around the proposed development
• Provide a comfortable wind environment around the proposed development
• For any design mitigations, ensure they preserve the initial concept, speak to the heritage aims, are minimal, are cost efficient and effective

Design mitigations can include altering the massing and form of a building, and/or landscaping of trees and artworks at pedestrian level, and/or other management strategies. We found that active management was possible for some local balconies but not for the majority of affected areas. It was clear that, for The People鈥檚 Project, the challenge would be extensive to work through. Parallel studies were initiated.

MEIS was proactive in developing some variations of massings. We quickly developed a full CFD design model which we calibrated against wind tunnel tests and used to quickly assess these alternatives. In parallel, we examined an extensive number of mitigation designs 鈥� considering areas of tree planting, modifications to the facade to break-up wind, and areas of landscaping banners.

From first wind tunnel testing in December 2017, moving to planning through further tunnel testing and CFD, we explored a huge range of studies. These included 6,907,680 pieces of data that came from 78 mitigation options for the required safety and design criteria, encompassing five seasonal studies across spring, summer, autumn, winter and annual. Data was gathered from 246 probe positions embedded within the wind tunnel testing (WTT), tracking 36 directions at 10 degree intervals.

We developed the mitigation design as part of pre-planning and submitted through all parties for discussion. In October 2022, we delivered a three hour, 120 slide presentation to Liverpool Council. Planning was achieved but the story doesn鈥檛 stop there, as we (海角视频, the client, council, and architect) continued to consider and refine the complex wind issue to optimise and create an improved design.

A solution that mitigates wind and elevates the spectator experience

As the design stood, wind mitigation devices had been introduced as integrated into sculptures and banners, but any such interventions are always going to disrupt people flow. Also, the mitigation around the western corners of the stadium was not sitting easily into the overall design.

The team reflected on whether there was something missing from the design, and with it a further opportunity for the project. Architects BDP Pattern took a fresh look and created the notion of the western terrace. This offered something more to the project, adding to the composition while also providing a new concept that could stabilise the western corners against wind.

A further series of detailed options was modelled which were all tested under CFD for a full range of wind conditions. The final choice (shown in the figure below) was found to significantly improve wind conditions. From this, a submission was made to the planners with the new developments, and the stadium design as we see it today was approved.

The wind engineering was one of the most challenging parts of the project, and that is also what made it one of the most enjoyable. Working closely with the client and the wider project team, we were able to provide outstanding creative and problem-solving support in navigating a difficult phase of the project. Determined to find the best solution, we pulled together to deliver a final mitigation design that solved the problem of high winds while creating a welcoming new terrace for visitors and spectators to enjoy.