Samuel,
The big traffic issue seemed to be the throughput of cars into parking. We were 2.5 km south of Sanson at 0900. Three and a half hours later we had moved 4 km with another 5 km to run to get to the parking area via the tortuous route. However, without that route the SH1 queue would have been back to Paraparaumu!!!
We went home. Family gutted as it was their first opportunity to see the RNZAF since we arrived in the country in 2005 as my role has been to work out of Wellington so no base life for the family.