Cambridge Bypass traffic volume change

This post starts with the same question as this earlier post 4 lane roads – when to

Frequently Asked Questions (FAQ) – 2008 Transit NZ – Cambridge-bypass-2008-web-page.

7. Why are you only building two lanes? Two lanes will be adequate for some time, according to modelling of traffic flows. So Transit is planning an initial two-lane highway with the possibility of some passing lanes. Provision is being made to expand this into a four-lane highway as future traffic demand requires.

Question one from this FAQ web page gives nominal traffic volumes.

1. Why is the project needed? The existing SH1 alignment through Cambridge township carries over 20,000 vehicles per day and has a posted speed of 50km/h over a considerable part of its length. A large number of intersections also add to congestion and delays. The bypass will divert the high volume of through traffic, with its large number of heavy commercial trucks, away from the town and the narrow Karapiro Stream Bridge.

NZTA has not published a traffic count above 20,000 vpd for 6 years on the south side of Cambridge, as shown in the table below. This table also includes NZTA count Site 20, further south on SH1 near Karapiro. This is a Telemetry location that gives monthly updates of traffic. * 2014 is showing this year as a 6 month average, which shows a 4 to 9 percent change. This should see traffic in Cambridge back to 2006-2007 levels.

2006 2007 2008 2009 2010 2011 2012 2013
568 Cambridge – 50m Nth of Karapiro Bridge
Car 18,341 18,899 17,888 17,729 17,406 15,306 17,536 16,655
Heavy 2,221 2,077 1,988 1,883 1,956 2,107 2,414 2,357
Total 20,562 20,976 19,875 19,612 19,362 17,413 19,950 19,012
574 Karapiro Telemetry Site 20 *2014
Car 12,972 13,390 12,753 13,064 13,209 13,078 12,799 13,031 13,604
Heavy 1,490 1,538 1,822 1,549 1,517 1,551 1,566 1,594 1,750
Total 14,462 14,928 14,575 14,613 14,726 14,629 14,365 14,625 15,354

As part of its information days, NZTA published some 2021 predicted traffic flows. The Cambridge section poster was created in Aug 2010, showing traffic volumes of between 12,600 and 17,500 vehicles per day (vpd) and the Tamahere section poster was created in Dec 2011, showing slightly lower traffic flows of 17,200 vpd, pushing future demand for a 4 lane expressway even further into the future. The last image, which is a snap shot from the Southern links poster created in May 2012, shows predicted daily traffic flows for year 2041  at 19.500 vpd.

Cambridge effect on local network 11 May  SH1 Tamahere section: Effects on the Road Network   Cambridge bypass Southern Links traffic-flows-2041 East

And last from Access Hamilton network action plan – 2010 – page34 If this was Hamilton City rate payers’ money, 19,500 vpd may not trigger 4 laning.

Wairere Drive has shown that this two lane carriageway can accommodate traffic volumes up to 26,300vpd (2008 traffic volume) before 4-lanes are affordable and effective.

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