Charting Transport

[Last updated March 2012, originally posted in April 2010]

What are the trends in traffic volumes on major roads in Australian cities? Unfortunately there isn’t a lot of data published about public roads, but most toll road operators do publish data on a regular basis. So I thought I’d take a look..

Traffic growth on roads with regular data

The first chart shows the relative growth in traffic volumes on several toll roads in Melbourne, Sydney and Brisbane (where regular data is published) since 2006:

You’ll probably need to click to zoom in to see all the detail (sorry the chart is a bit cluttered).

Another way of looking at this data is to consider rolling year on year traffic growth:

Some observations:

• Most roads had a decline in traffic growth during 2008-09 (probably due to the GFC), rebounded in 2010 (except Sydney’s M4, where tolling ceased in 2010), and then growth declined again in 2011 (possibly due to economic slowdown).
• Growth has been much faster on non-radial roads. This might reflect the creation of new demand corridors as these roads provided significantly better links to the established road networks. But it also might reflect the low base from which the traffic volumes grow on these road. The high growth roads are:
  • Melbourne’s Eastlink, which runs north-south in the outer Eastern suburbs (I have set 2008Q4 as the baseline for Eastlink as it wasn’t open in 2006).
  • Brisbane’s Gateway and Logan Extension Motorways, most of which is an east-west freeway in the southern suburbs.
  • Sydney’s Westlink M7, which mostly runs north-south in the western suburbs.
• Melbourne’s CityLink saw dramatic growth in traffic in 2010, rebounding from a period of extensive road works (contributing to a decline in use in 2009). This growth eased off in 2011, perhaps returning to a 3% growth trend(?). The road upgrade appears to have had an impact on train patronage – refer another post.
• Traffic volumes on Sydney’s M2 declined in late 2011 (probably due to major roadworks).

Unfortunately data isn’t always readily available:

• The Brisbane Gateway Bridge and Logan/Gateway Motorway extension data is only available for financial years in annual reports up until 2010. A 2011 annual report has not published on their website last time I checked.
• In October 2011, Horizon Roads purchased Melbourne’s Eastlink, and they do not seem to be publishing traffic volumes.

Note also that less than 2 years of data is available for Clem7 and the Lane Cove tunnel making trend analysis difficult at this point.

Traffic growth on other toll roads

Sydney Harbour Bridge and Tunnel

RTA report data on traffic volumes every three years (in theory), but unfortunately the last published data is for 2005. However (as is often the case) some data was incidentally published about traffic volumes in 2008 and 2009 (close to, but not quite calendar years) following the implementation of time-based tolling.

I have plotted these on the following chart:

The Sydney Harbour Tunnel opened in 1992, and you can see total traffic volumes grew rapidly in the mid 1990s, before stabilising around 2002 (perhaps because capacity was reached).

Note that the 2008 and 2009 data points are twice the average weekday southbound traffic volumes. The true average all-week two-way traffic volume might be lower when weekends are taken into account, but might be higher if people make circular trips only crossing the harbour bridge/tunnel in the (free) northbound direction.

Sydney Cross City Tunnel

While there isn’t regularly published traffic data published that I can find, a 2006 NSW Auditor General’s report contains some traffic volume data for 2005 and 2006, reproduced here (from page 32 of the report).

It would appear that motorists are highly sensitive to toll pricing.

Brisbane’s Clem7 cross city tunnel

Brisbane’s first new road tunnel, the Clem7, opened in March 2010. During the first three weeks of toll-free operation, there was an average of 59,109 vehicles per day. During the first week of tolling, this fell to 20,602. The forecast was for initial traffic of around 60,000 vehicles per day, rising to 100,000 within 18 months.

Rivercity Motorways have gone to the extraordinary step of publishing daily traffic data, as can be seen in the following chart showing traffic volumes since tolling commenced:

You can see an uptick from the beginning of July 2010, when toll prices were cut. Tolls were raised in November 2010 and again in April 2011 and you can see corresponding drops in traffic volumes (suggesting a strong price elasticity effect). Average daily traffic in calendar 2011 was 10% lower than for the first 12 months of operation (includes one overlapping quarter).

During the 2011 flood crisis tolls were waived for one week, and at the end of that period on Monday 17 January 2011, 40,566 vehicles were recorded, the highest since tolling commenced. This may or may not have also reflected closures to other roads making Clem7 more attractive.

(footnote: actual weekend volumes have not been published for April 2010, so I have substituted the average non-workday figures, that have been published).

According to Wikipedia, this covers all major toll roads in Australia in operation at the time of writing. I’ll try to update these figures periodically.

Eastlink volumes compared to forecast

The following chart shows that Eastlink actual traffic volumes have been fairly consistently around 60-65% of original (2004) forecast since tolling began. It suggests the forecasts were good at estimating the ramp-up shape, but not so much the overall traffic volumes!

Note: ConnectEast issued revised forecasts in August 2009, including that (steady state annual) average daily trips in 2011 would be 209,900. That forecast doesn’t appear to have been realised either. Unfortunately data reporting stopped in October 2011 following the sale to Horizon Roads.

Maps of toll roads:

Brisbane Motorways

Sydney Motorways

Melbourne Citylink, Eastlink

Other sources of traffic volume data

See another post on Melbourne traffic volumes.

Some interesting recent data on Brisbane traffic volumes is in this report prepared for RiverCity Motorways (who operate the new Clem7). It shows many major roads in Brisbane with stable or declining traffic volumes (possibly because they are at capacity, or possibly because of a mode shift to public transport).