Ask Phoebe: Red patches remind drivers to slow down

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Can you tell me what the red patches are for on SH2 between the Bombay deviation and Maramarua? Kerry Brear, Auckland.

I can.

The Transport Agency says the red patches are part of their safety initiative to alert drivers to changes in the speed limit along SH2 on the Waikato side of the Bombay Hills. The painted patches are located beside the large speed limit signs at significant locations along the highway.

What is the planned start date of construction for Penlink - the planned toll link along the Whangaparaoa Peninsula from the Northern Motorway just south of Silverdale? Derek Smith, North Shore.

If you visit the Auckland Transport website (aucklandtransport.govt.nz) and go to the Improving Transport tab, you will find an up-to-date link to the Penlink project, which answers your query in detail. The less happy news is that Penlink is not in the current three-year funding round, but is likely to to be in the four to 10 year plan.

On the Northern Motorway soutbound lanes, when will Greville Rd to Tristram Ave be three-laned? And when will the SH1/SH18 intersection be upgraded to motorway standard? Again, Derek Smith, North Shore.

The NZ Transport Agency, Auckland Transport and Auckland Council are working together to improve the transport system across the wider North Harbour area. The first priority for the NZTA is to increase the room available for northbound traffic on the Northern Motorway (SH1) between Upper Harbour Highway and Greville Road, including interim improvements to the Greville Road interchange. Construction is expected to start in mid-to-late 2013. Longer term, the NZTA will upgrade SH18 to full motorway standard including an interchange at the SH18/Northern Motorway intersection.

There are several "traffic sensors" - black tubes across the road connected to a unit chained to a lamppost - around Mission Bay. I presume they count vehicles. Do they also record the speeds of passing vehicles? Ross Stevenson, Mission Bay.

Yes, they do. The tubes across the road are used to count vehicles, record traffic speeds and, depending on the system, can also determine the classification of the vehicle passing over the tube, for example whether they are a car, motorcycle or a heavy vehicle.