Pennant Hills Rd and the impact of NorthConnex

It’s been just over a month since the NorthConnex tunnel has opened up, and it is noticeably quieter along Pennant Hills Rd. Some people are even lamenting that their weekly semi-trailer run is not the same anymore 😉

So what are the numbers? We’ve had a look at the Transport for NSW OpenData Traffic Volume Counts dataset, and pulled up the stats for Pennant Hills Rd.

Transport for NSW uses different types of traffic counters. There are tubes across the asphalt, loops inside the road surface, there are cameras, and several other types as well. They all work in different ways to count the traffic volumes. Some of these are temporary, some are permanent, some do classify vehicles by size, others don’t.

There are currently 3 so-called axle pair counters in operation in our area, one near Mt St Benedicts school East of Loftus Rd, one just East of Beecroft Rd, and one just West of The Crescent. The Loftus Rd one counts traffic in both eastern (towards the M1 near Hornsby) and western (towards the M2 near Beecroft) directions, the one near Beecroft Rd counts westwards traffic only, and for the one near the Crescent it is not clear which direction it goes to.

The westward counters for East of Loftus and West of The Crescent do match quite well. The data from the East of Beecroft counter is a little harder to work with, it seems to be compiled from two separate counters and one needs to do a bit of manual labour to add the numbers for each day We’ll leave that for later.

Looking at the numbers, and looking at the first of November, the day the tunnel opened at 0:00am midnight, we can see a huge jump in counts. From an average count of around 28’120 counted axle pairs in October, it dropped down to 21’183 in November (26 days of data). That is a reduction of 25%! Assuming one axle pair per car, 1.5 pairs for a small truck, 2.5-3 for a truck and trailer, and 3.5-4.5 for a B-Double semi, it equates to approx. 6940 axle pairs less, or approximately 2’530 trucks less. And that is only in the westward direction! Eastwards, we can see a very similar reduction, so we can estimate that the total number of trucks removed is indeed approx. 5’000 per day.

The counter East of Loftus Rd seems to have a little bug – the eastward count is about 2/3 of the westward count. As it is unlikely that 33% of the traffic to the M2 does not ever return, or always returns via a different route, one can reasonably suspect that one out of the 3 Eastward loops is not counting anything at all, so we’re missing one of three lanes here. The total daily count for East of Loftus Rd is therefor close to twice the westward count.

We can also see that there is significantly less traffic on the Sundays, around 30% less than on Fridays.