With almost 60 per cent of roads in Northland unsealed the policy would make a ''huge difference'', he said.
"I've been a strong advocate of sealing our roads here in the North because I've seen first-hand the effects of unsealed roads ... we need to get on with upgrading the most important.
"Councils really struggle to pay for the cost of sealing roads, particularly here in the North, and it's time central government stepped up to the plate.''
Northland roads by numbers
Northland has one of the highest proportions of unsealed roads in the country. Overall the region has 5820km of roads (excluding state highways), 3440km of which (59 per cent) are unsealed. Whangārei is in a relatively good position with just 40 per cent of its 1750km of roads unsealed, but in the Far North 65 per cent of its total 2510km is unsealed. In the Kaipara, with a tiny ratepayer base, 71 per cent of its 1570km network is unsealed. Using an average of $500,000/km, the cost of sealing only the most important routes — the so-called primary and secondary collector roads — would be an astronomical $141m, $116m of which would be in the Far North. Sealing every road in Northland would cost about $1.7 billion.
Bishop said the NZ Transport Agency, which administers the subsidies, spent just $6.4m sealing rural roads nationwide in 2018 because it was seen as a low priority.
''We're saying, we'll increase the subsidy, ring-fence a minimum of $15m a year for 10 years, and make it happen.''
The new subsidies would be set between 60 and 80 per cent — up from the current maximum of 66 per cent — with the highest level applying to Northland, Bishop said.
Government subsidies are necessary because the cost of sealing roads is so high, up to $1 million a kilometre, that it is beyond the means of many councils, especially those with a large area but few ratepayers.
Currently NZTA pays a 66 per cent subsidy to the Far North District Council (about to go up to 69 per cent) for sealing, but only if the road meets strict criteria.
The subsidy is 53 per cent in Whangārei and 61 per cent (soon to be 62 per cent) in Kaipara. The councils have to stump the rest of the cost.
The Far North District Council sets aside $1m a year for its share of sealing costs with a one-off boost last year to $4m. Whangārei budgeted $2m last year but asks residents to contribute while Kaipara currently has a policy of no new sealing for cost reasons.
NZTA subsidies are not the only source of money for sealing rural roads.
Late last year the government's Tourism Infrastructure Fund granted $800,000 to finish sealing Pungaere Rd, a tourist route from Waipapa to Puketi Forest.
The Provincial Growth Fund has also allocated large sums to rural roads, including an announcement last week of $6.5m to seal Ruapekapeka Rd from Towai to the pā. As well as providing access to a historic battleground, Ruapekapeka Rd is an alternative route when State Highway 1 is closed.
