Asked whether roading should be prioritised over issues like housing, health and education, English said the projects would support housing around New Zealand.
"More housing needs more roading, more water infrastructure," he said. The roading projects would allow the Government to "get ahead of the curve on growth".
Some of the proposed highways, like the East-West Link, are already in the planning stages but classing them as nationally significant means their funding is guaranteed and they are likely to be completely more quickly.
The East-West Link, which runs from Mangere inlet to Mt Wellington, has proved controversial because of its price tag of around $1.8 billion and its impact on land which is sensitive to local iwi Ngati Whatua.
Asked whether a Labour Government would scrap any of National's proposed roads, Labour leader Jacinda Ardern said the East-West link would be "scaled back" because the business case did not stack up.
The party has already committed to reopening the Manawatu Gorge, which is also on National's new list of highways.
Ardern said her party would place greater emphasis on a mix of transport infrastructure.
"There has been a lot of focus from this Government ... on roads, and the regions need rail as well," she said.
Her party is expected to announce a regional rail policy tomorrow. The Green Party will also announce a major public transport initative.
Bridges said the estimated cost of the 10 projects was $10.5 billion, compared to the $12 billion for the previous seven Roads of National Significance. The projects were chosen because they were New Zealand's highest-volume roads, he said.
They would be funded through the National Land Transport Fund and private-public partnerships. The initial funding had already been committed to in this year's Budget.
The seven previous projects were the Puhoi-Wellsford highway, the Western Ring Route in Auckland, the Victoria Park tunnel, the Waikato Expressway, Tauranga's Eastern Link, Wellington's Northern Corridor, and motorways around Christchurch.
Nationally Significant Roads:
• Wellsford to Whangarei
• East West Link in Auckland
• Cambridge to Tirau
• Piarere to the foot of the Kaimai Range
• Tauranga to Katikati
• Napier to Hastings
• Manawatu Gorge
• Levin to Sanson
• Christchurch Northern Motorway
• Christchurch to Ashburton