Commuters lined up in droves in anticipation of the opening of Sydney's new Wynyard Walk on Tuesday, hoping to catch a glimpse of history as they snapped pictures on their phones.

And as soon as Premier Mike Baird and Transport Minister Andrew Constance had cut the ribbon, the crowd poured through the entrance of the 180-metre pedestrian tunnel linking Wynyard Station to Barangaroo.

About 23,000 workers are eventually expected to be based at the fast-growing precinct on the western edge of Sydney's CBD, while a further 30,000 people are forecast to visit each day.

For them, the new tunnel will halve the time it takes to walk from the train station to Barangaroo - it will take about six minutes. Four years in the making, the nine-metre wide tunnel can handle about 20,000 people an hour, and features escalators, stairs and lifts.