"Significant ground improvement works under the box structures are required to support the bridge approach ramps which was different from the assumptions at concept design. The high groundwater table at this location would also pose significant challenges.
"The underpass would have had to be built in stages while moving traffic lanes back and forth to keep the busy state highway open to traffic. A complex staging sequence meant construction would have a significant impact on the potential costs and time to build the underpass."
In December 2016, the Bay of Plenty Times revealed the agency's plans to demolish the original underpass as part of construction works for the Baypark to Bayfair Project. Pedestrians and cyclists were expected to navigate up to 11 lanes of traffic with controlled crossings instead, sparking strong opposition from many residents including community cycling groups.
In May, 2017, the transport agency revisited the plans and in November 2018, announced changes to include a new pedestrian and cycle underpass following community feedback at the removal of the existing underpass. The final costs to build the underpass were to be determined once the detailed design was complete.
"While we anticipated that including an underpass at this stage of the project would be expensive because of its complexity, it became unfeasible when the extra time and very significant cost was added to the existing contract," Thackwray said.
Bike Tauranga chairman Kevin Kerr said he was "absolutely gutted".
"If their numbers are correct, you cannot justify spending $33m on an underpass, so I do understand."
Kerr said his focus now was to work on safe options for pedestrians and riders to use the Bay Link.
The current underpass will close in September 2019 to allow for ground improvement works for the approach ramps to the flyover to be built.
Temporary signalised crossing points will be installed near the existing underpass on Maunganui Rd to provide safe crossing for pedestrians and cyclists.