The height of Penlink’s Wēiti River Bridge is almost the same height as the iconic Auckland Harbour Bridge.

The bridge is a part of the Penlink road, which is being built across the Wēiti River and stands at a height of about 46 metres above the highest point in the river.

Due to its height, wind loads will play a significant role in the design and construction of the bridge. 

A wind load is the force exerted by wind on an object and when it blows against an object, it creates pressure that can push or pull on the object. 

When designing a bridge, the Penlink project team has taken wind loads on the structure, as well as the safety and comfort of its users, into consideration. 

This includes pedestrians, cyclists, cars, trucks, and motorcyclists. Trucks and motorcyclists are particularly vulnerable to high winds.

To calculate wind effects on the bridge and its users, the team used a wind load formula and published drag coefficients. 

They used drag coefficients to calculate and compare wind load against different parts of the bridge, and this helped them create structures that are resilient in the face of extreme wind forces.

Penlink is also undertaking wind tunnel testing of key components to confirm the accuracy of their calculations. 

This testing is currently underway in a specialist wind tunnel facility in Denmark and will be completed in the next six weeks. 

The wind tunnel testing allows the team to observe the performance of key bridge components in controlled wind conditions.

The detailed design of the Wēiti River Bridge will continue for about another seven months, and the team will use insights from the wind tunnel testing to create a robust and resilient bridge design.