The fines for trespassing on the Sydney Harbour Bridge could be tripled after a mentally ill man brought traffic to a standstill by climbing onto the iconic structure before peak hour.

The 43-year-old man sparked a major police operation lasting five hours, with NSW Police later saying he climbed up the bridge due to a "family issue" and he suffered "significant mental health issues".

The man scaled the bridge about 4.30am on Wednesday and surrendered to authorities just after 9.30am. He was handcuffed by police rescue officers and brought down to the ground.

NSW Roads Minister Melinda Pavey labelled the bridge climb a "premeditated event" and is considering tripling the current $3000 penalty for trespassing on the structure.

The minister suggested the $10,000 fine for illegally climbing San Francisco's famous Golden Gate bridge was a "good starting point".

Superintendent Michael Fitzgerald says the man - who rode a bike to the bridge - was known to police and would face "significant charges" after being treated in hospital.

Traffic was backed up 20 kilometres from the bridge during peak hour with authorities closing several northbound lanes as negotiators talked with the man.

Supt Fitzgerald said authorities would work with the Roads and Maritime Service to make the bridge more secure.

Climbing the Harbour Bridge is illegal unless authorised, for example as part of an official Bridge Climb Sydney tour.

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© AAP 2018