Infinity Bridge

Infinity Bridge
County Durham, Yorkshire
The Infinity Bridge from the Tees Barrage
Location
Carrying:	Pedestrians and cyclists
Crossing:	River Tees
Location
Grid reference:	NZ45411907
Location:	54°33’53"N, 1°17’57"W
Structure
Length:	787 feet Main span: 394 feet
Design:	Asymmetric double tied arch and suspended deck
Material:	Weathering steel, stainless steel and reinforced concrete
History
	Built December 2008
Information

The Infinity Bridge is a public pedestrian and cycle footbridge across the River Tees, between Stockton-on-Tees town centre in County Durham, to the university and industrial estates on the opposite bank in the North Riding of Yorkshire.

The name of the bridge The name derives from the infinity symbol (∞) formed by the bridge and its reflection in the water.

The bridge illuminated after sunset, showing ∞ reflection

The bridge is half a mile downriver of Stockton town centre, between the Princess of Wales Bridge and the Tees Barrage. It connects the Teesdale Business Park and the University of Durham's Queen's Campus in Thornaby-on-Tees on the Yorkshire bank.

The bridge had the project title North Shore Footbridge before being given its official name Infinity Bridge, chosen by a panel of representatives from the funding bodies, from a pool of names suggested by the public.

Description

The bridge is a dual, tied arch bridge or bowstring bridge. It has a pair of continuous, differently-sized structural steel arches with suspended precast concrete decking and one asymmetrically placed river pier. The tapering arches with a trapezoidal box section are fabricated from weathering steel plate.

Each of the arches bifurcates within the spans to form a double rib over the river pier.

A reflex piece between the two arches holds them together, making the two arches one continuous curve. No other bridge is known to have quite the same design.

The offset river pier is to accommodate water sports and leisure craft to one side. The river pier is supported by an 11.5 m square by 2.5 m thick pile cap on sixteen 1 m diameter hollow steel pipe piles. On the pile cap beneath the water line are four 3 m cylindrical concrete legs, onto which are bolted and welded the four inclined grey steel legs visible above water.

Riprap covers the river bed around the river pier for scour protection against the large flows when the Tees Barrage downstream discharges.

The bridge deck is 16 feet wide and 13 feet between its custom-made handrails.

The main arch of the bridge is 394 feet long, weighing 300 tons, and 105 feet tall, with its top 131 feet above the Tees. The short arch is 197 feet long and 52 feet tall. The hangers (droppers) are spaced 25 feet apart and are made from high-strength, locked-coil steel cable.

To ensure any bridge oscillation is controlled, the deck is fitted to the underside with seven tuned mass dampers – one on the short arch, and six on the larger weighing 5 tons in all. The mass dampers control horizontal as well as vertical oscillations — a feature only required on very slender bridges. There is provision for the addition of further dampers when the issue of maintenance arises.

The clearance (heading) below the decking on the navigable part of the river is 8 m.

Illumination

A special feature is made of the way the bridge is lit at night.

At night the bridge handrail and footway are lit with custom-made blue-and-white LED lighting built into the handrail that changes colour as pedestrians cross the bridge; sensors trigger a change from blue to white, leaving a 'comet’s trail' in the person's wake. Attached to the steel cable ties are white metal-halide up-lighters to illuminate the white painted bridge arches, and blue LED down-lighters to illuminate the water and ground surfaces immediately below the deck. At night from certain viewing angles when the river surface is flat calm, the twin arches together with their reflection in the river appear as an infinity symbol <math>\infty</math>, and it is this effect that inspired its name.

Uplighters on the southern riverside pier illuminating the southern end of the arch Uplighters on the southern riverside pier illuminating the southern end of the arch   White metal halide up-lighters and blue LED down-lighters, attached to two steel tie cables running along either side of the bridge walkway White metal halide up-lighters and blue LED down-lighters, attached to two steel tie cables running along either side of the bridge walkway   Handrail and integral custom-made walkway lighting Handrail and integral custom-made walkway lighting

Outside links

• Infinity Bridge at Structurae
• Infinity Bridge: Bridges on the Tyne
• Construction animation: Oasys
• Images:
  • Dorman Long Technology
  • Flickr.
• Bridge model: Imperial College.

Pictures

("Wikimedia Commons" has material about Infinity Bridge)

The smaller south arch The smaller south arch   The larger north arch The larger north arch   Central pier and large arch Central pier and large arch   The central pier The central pier   The southern riverside concrete pier with reaction plate viewed from the north side The southern riverside concrete pier with reaction plate viewed from the north side   The south riverside pier and concrete decking The south riverside pier and concrete decking   The seven south piers and approaches The seven south piers and approaches   The north riverside pier and abutment The north riverside pier and abutment   An angled dropper, deck support and bowstring cables An angled dropper, deck support and bowstring cables   Tie cable tensioning clamps on the north bank Tie cable tensioning clamps on the north bank   Infinity Bridge information board Infinity Bridge information board   Infinity Bridge from the River Tees Watersports Centre Infinity Bridge from the River Tees Watersports Centre