The inclined elevator at Ian Simpson Architects' exhibition space is far more inviting than an anonymous escalator As a city, Manchester is a unique microcosm that reinvents and renews itself every so often in response to the changing patterns of society. The process started in Victorian times; you have to look hard to find medieval Manchester.
Whereas 20 years ago less than 500 people lived in the city centre, today the centre is alive with old and new loft apartments. And while a single street, King Street, used to be the fashionable shopping area, the shops have now spread east and west, almost reaching to Piccadilly and Victoria stations.
So it was appropriate that Manchester City Council should commission an international competition to design a building to house 'a permanent exhibition that explores people's experience of cities'. The competition was won by one of Manchester's brightest young practices, Ian Simpson Architects.
The winning design, called Urbis, is a translucent shard of glass with a dramatic sloping roofline that echoes a four-storey cascade of open-plan floors inside. The site is a former car park just west of the new department stores that replaced those damaged by the 1996 IRA bomb. It is familiar to the practice, which worked on the masterplan for the adjacent Millennium Quarter.
The building is shaped to create a quiet enclosure away from the street which, it is hoped, will be animated with visitors. As the roof makes its downward slope, the building swells outwards in plan, reaches the ground floor and curves round in a 'boomerang' edge to form the main entrance and ticket office. It is clad with a double wall of glass.
The external single-glazed skin consists of panels of glass. Most are sandblasted but occasional clear panels - in the cafe, for instance - give views out and intriguing glimpses inside.
The real surprise comes when you go through the doors: turn around and in a giant vault of space you can see the floors stepping up in open tiers, reached by an inclined elevator, which glides slowly up and down on a huge steel truss.
'We wanted to get away from the anonymous nature of an escalator in a shopping store, ' explains Ian Simpson. 'The inclined elevator creates a moving element that is part of the building.We envisaged the journey as part of the process of visiting the exhibition'.
In addition, the choice of an inclined elevator makes better use of the limited volume within the building. It is slotted hard against a glazed external wall and its gritty steel structure contrasts well with the smooth glass and the clean cast-in-situ concrete floor slabs. Because it is used with a counterweight and does not run continually, the system also consumes less energy than conventional escalators do.
Having bought their tickets to the exhibition, visitors take the inclined elevator to the top floor. The elevator car has transparent walls and roof, with stainless-steel-clad doors. As visitors rise slowly, they are offered views of the city through the etched glass facade.On arrival at the fourth floor, the elevator's doors open to reveal the exhibition.
In this way, the elevator controls and frames visitors' introduction to the experience.
Visitors then progress through the exhibition, descending to the ground floor by means of staircases, with opportunities to stand and look down at the edges of every gallery floor. The exhibition spaces are flexible - they were designed long before this particular exhibition concept was finalised - and they take the form of a light-filled promenade rather than the more usual 'black box' approach. It suggests that whatever may be on show inside, this is a building that will become an integrated part of the city.
An inclined elevator supported by a steel truss structure Rather than a separate structure supporting a proprietary lift product, the truss was conceived as a pair of rails on which the elevator car would run.
The car moves silently with nylon wheels on top of the truss, while the counterweight and cables run in the depth of the UB top rails. Moving parts are painted yellow and contained by perforated stainless steel, as required by lift regulations, ensuring the operation of the elevator is animated throughout its cycle.
The car has a stainless steelframed floor and roof, with structural glass walls that are curved at each end. The floor is of heavily sandblasted glass with a perforated stainless steel border, which permits natural ventilation. The roof is made of glass and perforated metal; two fans mounted in the roof run at peak periods to maintain comfortable temperatures.
One of the challenges resulting from the design of the truss/track was the control of deflections at landings. With a 25m span and a car with variable loads, a conventional truss could have incurred considerable movement. As a result, the truss comprises top rails of 564 x 186mm UBs and bottom rails of 245mm CHSs, which are connected by 152 x 152mm UB cruciform frames. It is further stabilised with a matrix of tension rods along its sides. The bottom rails 'peel away' from the truss to form inclined support legs. At entrance level these are splayed to frame circulation.
The installation rests on four steel ball-and-socket joints set in the ground floor.
ARCHITECT Ian Simpson Architects
STRUCTURAL ENGINEER Martin Stockley Associates
COST MANAGER Davis Langdon & Everest
MANAGEMENT CONTRACTOR Laing
SUPPLIERS Inclined elevator car and truss WGH Transportation Engineering