Vehicle traffic counts along State Highway 1 from 1995 to 2008 are estimated to include: 1) Through traffic of approximately 12,000 vehicles travelling between regions. 2) Kapiti residents commuting to Porirua, Hutt Valley and Wellington of around 8,000 vehicles. 3) Residents of Pukerua Bay, Paremata and Porirua commuting to Wellington, making up the highest counts between the Wellington Motorway and Pukerua Bay stations.

1. SH1 Mean Daily Traffic Count, Estimated Categories
40,000
Pukerua, Paremata, Porirua to Wellington Commuters
Vehicle Count (No. Travelling N & S) Kapiti Local Traffic
Kapiti to Porirua, Hutt, Wellington Commuters
30,000
Through Traffic
20,000
10,000
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Trends in SH 1 traffic flow at recording stations (vehicle count, travelling both north and south),
mean values for the years 1995 to 2008. Data from Transit/NZTA State Highway Traffic Volume
Reports, online pdf files. (Traffic flow increased by an average of 1.65% annually over this
period.)
The “categories” shown are not given in the reports, and are estimated by me as follows:
Through Traffic: A value a little lower (rounded at 12,000) than the vehicle count at the
recording station south of Levin. It will include some Kapiti to Howhenua commuters.
Kapiti to Porirua, Hutt, and Wellington Commuters: A value (8,000) somewhat lower
than the vehicle count at the Paekakariki South and Pukerua Bay recording stations (less the
Through Traffic count). Through Traffic + Kapiti Commuters rounded at 20,000 vehicles.
Pukerua, Paremata, Porirua to Wellington commuters: The vehicle counts above the
Through Traffic and Kapiti to Wellington (etc.) Commuters, from the Motorway to Pukerua
Bay recording stations.
Kapiti Local Traffic: The vehicle count above the Through Traffic and Kapiti to Wellington
(etc.) Commuters, from Paekakariki South to Waikanae recording stations. The maximum
value (4,100) is on SH 1 just north of the Ihakara Street recording station.
The North of Ihakara St value (4,100 vehicles) is 17% of the total vehicle count at that station.
Heavy traffic (> 3 t), not shown on this graph, is 1200−1500 vehicles (10%) north of
Waikanae, 2000 vehicles (5−7%) on the Motorway (diluted by commuting cars).
A simpler estimation can be made by assuming that the rise in vehicle numbers in the Kapiti
area, say Paekakariki to Waikanae, represents the “local” vehicles using SH 1 for local trips.
The result is the same. Most of the traffic on Kapiti’s SH 1 is through traffic or Kapiti
commuters (and the distinction between these two groups is difficult to make and not very
relevant here).
I believe my 17% estimate is on the high side. Not all these vehicles would use a 2-lane WLR,
because their origin or destination would be closer to SH 1.
It is therefore difficult to reconcile these data with KCDC’s estimate of 22% of traffic using
the WLR.