Trains are back in service in Auckland today after a two-week shutdown for work including the installation of new signals needed to handle Rugby World Cup crowds.
Passenger services are expected to resume on the western line, the Onehunga line and between Otahuhu and Britomart on the southern line.
Buses will keep replacing trains for another week south of Otahuhu and on the eastern line as work continues on five replacement bridges and lowering of tracks through the 800m Purewa Tunnel west of Glen Innes for the $1 billion rail-electrification project.
Limited freight trains will run only along the southern line, using one set of tracks through construction zones.
KiwiRail has spent the fortnight since Boxing Day resignalling the critical Quay Park rail junction in downtown Auckland for the "bi-directional" running of trains needed to clear Kingsland Station of 15,000 rugby fans in 75 minutes after Cup finals.
That means trains will leave from both of the station's platforms in alternating departures every five minutes, a system to be put to its first big test on February 19 after the Super 15 rugby clash between the Auckland Blues and Canterbury Crusaders.
Resignalling Quay Park through to Britomart, which KiwiRail deemed the most challenging of a range of construction tasks, is also critical to the electrification project.
Auckland rail upgrade director Peter King defended the unprecedented scale of the shutdown, saying it had enabled crews to get far more work done. "Trying to do work with trains whistling past every 10 minutes is just impossible," he said.
"We've been able to achieve a huge amount, and a lot of the work to tidy up the track and get it to a reasonable state hopefully means we've got a network that performs pretty well over the next 12 months."
The summer programme has also included the erection at Newmarket and Baldwin Ave Station on the western line of the first 45 of 3500 power supply masts needed for the arrival of electric trains in 2013, and the construction of more than 300 mast bases at various locations.
Work will continue until the end of January on a replacement station at Baldwin Ave, bringing its two platforms closer together and making them long enough for six-car trains.By Mathew Dearnaley Email Mathew