New messaging for Over Height Detection System for Penrose Overbridge


Penrose Bridge is the lowest clearance bridge above Auckland’s motorways.

Despite a high-visibility LED early warning system the bridge has now been struck more than 50 times in the last decade.

From tomorrow (1 July 2023)  Waka Kotahi NZ Transport Agency is making changes to the Over Height Detection System (OHDS) to try and help prevent bridge strike. 

“We are altering the sensors so they will be set at the critical height limit,  that means if you now see the lights you are over height and will definitely hit the bridge”, says Auckland Systems Management Alliance Manager Paul Geck.

There will still be two illuminated signs preceding the bridge in both directions, but the messaging on them will also change to reflect the need for vehicles to stop.  

Before the Ellerslie off-ramp (southbound) and the Mt Wellington off-ramp (northbound) if the OHDS is activated by an over height load it will display the message:

Over Height Take Next Exit

If vehicles do not take the exit, the OHDS sign on the Penrose Bridge will display the message:

Over Height Stop

“This change is necessary to reduce the damage and disruption caused by bridge strikes. We often need to close the motorway in order to inspect and repair the damage after the bridge is hit.

“This understandably causes delay and frustration for other road users, not to mention it’s costly” says Paul Geck.

The most common causes of motorway bridge strikes include unsecured crane booms and digger arms, uncovered open containers, loose loads and loads that have shifted during transit. 

“If the warning sign is activated by an over height load, drivers are asked to move their vehicle into a lay-by and wait for assistance. We will dispatch responders to come help you.”

Under current guidelines the maximum height for a load is 4.3 metres, with over-dimension permits required when a load exceeds five metres. 

However, all loads over 4.3m height require written approval from Waka Kotahi to pass under all bridges spanning over motorways.

The Penrose Road overbridge sits 4.57m above the road.

“We believe the signs are pretty hard to miss, and would urge drivers to follow the instructions, otherwise the road user is at significant risk of serious injury and death.”

Waka Kotahi is asking heavy haulage operators and independent excavator companies to make sure drivers are aware of their surroundings when driving and is distributing guidelines to ensure drivers know the rules before setting out.

“When a bridge strike occurs, Police can issue infringements on the spot and Waka Kotahi can investigate and review a transport operator’s fitness to maintain a transport service licence and suitability to obtain a permit.

“In addition to compliance action, Waka Kotahi will seek to recover costs for the damage, which can be significant” says Paul Geck.