Charging Auckland drivers to use congested roads could be avoided if they shared rides with other commuters one in every four days, says a new transport think tank.
But Ridesharing Institute spokesman Paul Minnett, whose organisation is teaming up with Auckland University to find ways of removing 100,000 cars a day from the region's roads, acknowledged congestion charges might be needed to achieve that goal.
Mr Minnett, who is asking the Auckland Council for $20,000 of research "seed" funding, said freeing up the roads to that extent would be worth more than $500 million a year.
That is based on a Transport Agency calculation where each person who stopped driving would save everyone else $11.73 a trip.
"That is just the benefits to the transport system," he said. "There would be additional economic and environmental benefits from the change, such as improved energy security, faster delivery times ... expanding the growth potential of key employment destinations and improved air quality."
Mr Minnett said 400,000 one-person car trips to work each day consumed most of Auckland's road space.
Solo drivers were lugging 1.2 million empty car seats to work each day, causing an enormous drain on the economy and stress to commuters.
"Their empty seats represent wasted capacity that should be better used before we spend large amounts of money further widening roads, adding bus ways and building rail lines."