Puhoi to Warkworth motorway time savings unrealistic
Media release: Travel time savings claimed for Puhoi to Warkworth motorway are unrealistic
Warkworth based transport planning consultant Bevan Woodward has been studying the travel time savings claimed by NZTA for the Puhoi to Warkworth motorway.
Mr Woodward advises: "A slow trip from the tunnel to Warkworth currently takes 13 minutes. That’s an average speed of 78 km/h to travel the 17 km, but in my experience most trips are quicker than this - even during week day peak hour. The only time it's slower is during summer holiday congestion."
"For a 5 minutes travel time saving, the new 18 km motorway would have to be driven in a time of 8 minutes, this equates to a highly unrealistic speed of 135 km/h."
In addition Mr Woodward says: "If the new 18km motorway was driven at the legal speed limit of 100km/h, this would take 11 minutes. However as this is to the north of Warkworth, another one to three minutes must be added to drive through the Hill Street intersection into the town of Warkworth, meaning that there are no time savings on the existing travel time of 13 minutes."
"In NZTA's business case, claimed time savings of 5 to 8 minutes are used to calculate over half of the economic benefits of the proposed motorway. Without these unrealistic time savings the project is a very negative return on investment."
Here are the calculations...
Distance (km) Average speed (km/hr) Time (minutes)
Existing SH1 from tunnel into Warkworth (slow trip = 13 minutes) 17 78 13.1
Proposed Motorway (travel time saving of 5 minutes requires an average speed of 135 km/h) 18 135 8.0
Proposed Motorway @ legal speed limit of 100 km/h = 11 minutes travel time 18 100 10.8
A summary of key issues with the Puhoi to Warkworth motorway is attached.
Key issues with the Puhoi to Warkworth motorway
1) The claimed travel time saving of 5 to 8 minutes are unrealistic
A slow trip from the tunnel to Warkworth currently takes 13 minutes. That’s an average speed of 78 km/h to travel the 17 km, but most trips (even during peak hour) are quicker on this 100km/h stretch of road.
For a 5 minutes travel time saving, the new 18 km motorway would have to be driven at an unrealistic 135 km/h.
If the new 18km motorway was driven at 100km/h, this would take 11 minutes. However this is to the north of Warkworth, so when another one to three minutes to drive through the Hill Street intersection is added, it means that there are no time savings.
In NZTA's business case, the claimed time savings are used to generate over half of the economic benefits of the motorway. When these unrealistic time savings are removed from the BCR calculation, the project’s total economic benefit is a negative return on the Government’s investment.
2) The motorway’s single point of access to Warkworth is likely to negatively impact on the town.
Having only one access point to the motorway at Warkworth means making a compromise solution that will have potentially negative impacts on certain sectors and causes travel delays.
For example a single point of access to the North is likely to have very negative impacts for Warkworth retailers and it lengthens travel times between Warkworth and Auckland.
A single point of access to the south means the holiday traffic will continue to queue up over long weekends and public transport access through Warkworth is be impaired.
A single point of access to the west (eg: Woodcocks Rd) would put too much traffic past the College and does not solve the issue of holiday traffic congestion through Warkworth.
A bypass road with multiple access points (as outlined in point 4 below) resolves these issues.
3) We can’t afford it
The Government is borrowing $250 million a week to fund its budget deficit. Consequently, ratings agency Standard & Poor's recently downgraded the outlook on NZ’s national credit rating to negative, this has a direct cost for all New Zealanders.
4) There are more cost-effective solutions are available
Safety improvements on SH1, bypasses of Warkworth and Wellsford, provision of public transport, along with upgrading the Northern railway line is a far more cost- effective and comprehensive solution.
It will provide multiple access points to Warkworth and leave us better placed to with future issues such as:
• Deal with the effects of rising oil prices
• Reduce our carbon emissions
• Spreading the economic development across Rodney
• Providing public transport to the region
• Delivering travel time savings sooner