A bypass of Pōkeno was also constructed at this time, as well as several partially separated interchanges to allow access for local property owners along the route.

[6] A grade-separated interchange at Mercer was also constructed, incorporating an overpass for the southbound lanes to cross over the North Island Main Trunk railway (NIMT) at this point.

[8] The $210m[9] Mangaharakeke Drive section, originally known as the Te Rapa Bypass, was opened on 3 December 2012 between Horotiu and Rotokauri.

[10] Construction of the section of the expressway and Mangaharakeke Drive between Taupiri and Horotiu, bypassing Ngāruawāhia, began in late 2011 and was officially opened on 14 December 2013.

[18] In May 2017, the NZTA started consulting on a 16 km (9.9 mi) extension of the expressway, from the current terminus at Cambridge south to the SH 29 intersection at Piarere.

[22] On the grand opening day for the final section, a celebration of the completion of the entire expressway project was held.

[23] On the 16 km (9.9 mi) Cambridge section in the year following its opening, up to 50 serious crashes were avoided because of road safety barriers.

[34] A 2009 report for New Zealand Transport Agency (NZTA) concluded that the benefit cost ratio of the Expressway was 0.5, i.e. for every dollar of investment the return was 50 cents.

[40] In December 2020 the NZTA reported that an evaluation of extending the Waikato Expressway south of Cambridge 16 kilometres (10 mi) to the SH 1/SH 29 intersection at Piarere would be completed in 2021 but that there was as yet no funding for the project.