Following early engagement with the Franklin Local Board on the SH1 Papakura to Bombay project, the NZ Transport Agency Waka Kotahi has been investigating concerns raised over safety, congestion and access at Bombay Interchange.

Investigations and modelling have determined that the most appropriate short-term solution for the issues affecting the interchange is for the interchange to have traffic lights installed.

As a result of those investigations, these traffic lights will be installed at Bombay Interchange and the adjacent bp Bombay service centre exit on Mill Road Bombay, as shown on the plans further below.

The investigations and work undertaken on this project to date are summarised below:

  • In late 2019/early 2020, the Franklin Local Board raised concerns with the SH1 Papakura to Bombay project team on behalf of the community over safety and congestion at Bombay Interchange, particularly when using the southbound off-ramp.
  • In 2020, NZTA commissioned a traffic analysis of the interchange and, in early 2021, those investigations were undertaken and reported back.
  • In July 2021, the report and recommendations were presented to the Franklin Local Board. The report recommended that the southbound and northbound off-ramps and the northbound on-ramp at Bombay Interchange should have traffic lights installed.
  • In August 2021, at the request of the Franklin Local Board, NZTA began discussions with bp NZ due to similar issues experienced at the exit of the bp Bombay motorway service centre at 216 Mill Road, immediately beside Bombay Interchange.
  • In late 2021, further investigations and modelling were undertaken, including the Interchange ramps and the Bombay service centre exit.
  • In early 2022, nine different options for improvements at the interchange and adjacent service centre exit were modelled – all included benefits and drawbacks.
  • In the short-term none of the options modelled would be able to resolve all the congestion issues at the interchange and service centre exit.
  • However, signalising the interchange and the service centre exit with traffic lights right now will provide immediate and significant safety benefits for motorists using the interchange and visiting the Bombay motorway service centre.
  • A review was undertaken of the two short-listed options and the preferred option was progressed through to preliminary design and costing.
  • Since March 2022, regular updates have been reported back to the Franklin Local Board and Bombay community groups.
  • Topographical surveys, underground service plans and a draft concept design were completed by the end of 2022.
  • A preliminary design review, road safety audit and cost estimates of the selected option were completed by mid-2023.
  • Construction funding for the signalisation project was approved by NZTA in October 2023, and agreement was reached on a financial contribution from bp NZ towards signalising the adjacent Bombay motorway service centre exit.
  • Construction cost estimates were completed in early December and detailed design was completed by Christmas 2023.
  • Procurement is underway to appoint a construction contractor.  It is anticipated that construction will get underway in late April/May 2024.
  • The signalisation project will take 3-4 months to complete and will include both day and night works.

View the design plans [PDF, 11 MB]

Bombay interchange - aerial view

At Bombay Interchange, the northbound on-ramp, the northbound and southbound off-ramps and the adjacent exit of the bp Bombay motorway service centre on Mill Road will have traffic lights installed in 2024.