That's far from why she is stepping down as CEO of HVCCC - which co-ordinates the movement of coal via the train, terminal and port network to markets beyond - after close to seven years.

"It's technically very interesting and challenging, the interplay of all the needs and us being the balancing act ... and that's probably when I feel at my most competent and valuable and useful," she says of the stresses involved.

Weighing up another contract extension, Ms Molloy realised it was time to pursue new challenges. The first is in in September, when she hopes to be elected as the Hunter's representative on NRMA's board of directors.

A non-executive director on the boards of Hunter Medical Research Institute, Regional Development Australia Hunter and Hunter H20, among other committees, she wants to grow her board portfolio.

"Things rise up to boards because they are complex to solve and [I enjoy] working as group to solve that. I guess I bring a capability, arounds strategy, commercial knowledge and dealing with complex problems and developing positive cultures to work," she says. "To be able to have that impact in multiple organisations and industries just adds another dimension."

The NRMA position appeals to Ms Molloy because of its "strong community component".

"As a working mum, I also believe that we must not only plan our future but move quickly to develop new ways for our community to connect and move," she says.

She "feels good" about leaving HVCCC "in a good place", having been a part of a drive to build capacity in technology to improve services: "We've invested a lot in that and it's becoming part of the business ... Someone can come in and there is lots to do and they can move it forward."

Balancing the needs and demands of HVCCC's 20 members amid the highs and lows of the commodity cycle is a constant pressure.

"We are here for the good of the whole and sometimes that means parties don't get what they want because we have a high-level view - that creates conflict," she says.

Having battled to resurrect her career after maternity leave, Ms Molloy says things are better for women but says men are often penalised for seeking flexible work conditions, in turn penalising women.

She says gender diversity is lacking at executive level: "Whether it be gender or race, LGBTQ, or religion... there is a gap in leadership that doesn't reflect the diversity of society."