A row has erupted after a coroner called for a pedestrian bridge over the Northwestern Motorway where a schoolboy died taking a shortcut.

Guile Jackson, 12, of West Harbour, was struck by a car while on his way home at night in October.

Coroner Murray Jamieson held an inquest into the death and backed moves by Transit NZ, Waitakere City Council and Safe Waitakere to build an overbridge.

"I conclude that the provision of an overpass bridge ... will add to community safety and amenity," said Dr Jamieson in his finding.

"It will also enable action to prevent use of the drain under the motorway as an alternative crossing."

The dark, damp drainage tunnel's use as an unofficial shortcut to Westgate Shopping Centre has split the Massey Community Board.

Some members called it "the corridor of crime", said board chairman Andrew Good.

"Undesirables do their business and then dive off through the tunnel to get away.

"We have been trying to get Transit to stop people using the drain and an overbridge will encourage more foot traffic between Westgate on one side of the motorway and West Harbour on the other."

But board member Allen Davies, of West Harbour, said it would be a waste of money to build an overpass as a reaction to a death. "It's emotional claptrap ... Education is the way to stop the shortcuts."

Mr Davies argued that an overpass would not be much of a shortcut compared with the proper route to the Westgate shops - using the footpath and light-controlled crossing at the motorway's end.

Three board members are on an overbridge working party with Transit, the council and safety officials.

But Transit wants to keep the drain route open until an overbridge is built.

This could be two to three years away because money for the project depends on proposed extensions to the motorway, said regional operations manager, Hilton Netterville.

He said Transit had put up 2m-high fences along a 63m length of the motorway where Guile Jackson gained access and wanted to promote use of the drain until an overpass was built.

City councillor Ewen Gilmour, who is promoting road safety in schools, said it was ludicrous for some Massey board members to oppose the overpass.

"The coroner says it's the best option and it makes sense when you see a huge subdivision with thousands of people in it on one side of the motorway and a shopping mall on the other."

Westgate Shopping Centre owner IMF Westland told the council it was willing to share costs.