UPDATE: The open day has been cancelled due to weather. Read about Andrew Campbell's sneak preview of the TEL below.

A section of the Bay of Plenty's largest highway project is open to the public on Sunday as part of the first open day for the Tauranga Eastern Link.

The open day on Sunday from 10am till 2pm is mostly based at the information centre in Tara Road, but there will also be walking access from the Tara Road centre to the nearby section of TEL site.

Although most of the work on TEL is undercover, the public will be able to learn more about the work through the information centre and a limited tour of Tara Road.

The information centre is where the public is able to view progress via a computer fly-through, recent photos and models. There is also some of the machinery that is building the 23km road on display.

Apart from the section from Te Maunga to Domain Road, most of the highway is being built out of sight of the general public. A map is produced with the open day showing where people can drive to see different parts of the $450m project.

After months of preparation because of the peaty swamp soils, most of the highway west of the Kaituna is being built over, there is now more to see on the surface.

At some places, not much is happening. Wick draining is completed at the Domain Road interchange site and the area is now under pre-load. Engineers are waiting for the sand to sink further into the ground. They have sunk 3.5m so far and about another 1.5m is expected.

Sand embankments visible at other parts of the site are also areas under pre-load. The water is being squeezed out of the sub soil to provide a steady surface for the highway.

Another construction method being used is Mechanically Stabilised Earth walls – where 500mm layers of sand are separated by cloth to create stable sand embankments.

MSE is being used at the Mangatawa interchange, and the bridge abutments for the 150m Kaituna River bridge.

Sheet piling will protect the river bank when the 55m deep bridge piles are driven for the bridge piers.

Work on the bridge above ground comes after months of subsurface preparation necessitated by the fact the highway and the bridge are being built across centuries of bog and swamp.

At the Kaituna bridge abutments, in-ground rock columns have been placed under the abutments to counter the threat of liquefaction in earthquakes. Holes were drilled 15-20m into the ground and gravel dropped in as the drill shafts were withdrawn. The result is an invisible network of about 2000 underground gravel columns.

At the open day, you will see: latest construction progress photos, fly-through animation of the future highway, scale model of the completed Domain Road interchange, DVD presentations featuring construction footage and interviews and a section of the construction site open to public.

Activities for kids include: a virtual digger, bouncy castle for the kids and food and refreshments will be available.