Comment & Analysis: “Garbage in, garbage out” is an old computer science truthism dating back to at least the early 1960s. In terms of traffic modelling, it can be changed to “lack of ambition in, lack of ambition out”. This is key when it comes to transport and climate action.
Traffic models are used to predict changes in traffic and travel patterns. The National Transport Authority deceives it: “Transport modelling using mathematical techniques to create future year scenarios for population growth, land use, and transport networks, and assessing the impacts of these changes.”
On the need for modelling the authority adds: “The NTA undertakes transport modelling to support transport investment by enabling planners to make informed and data-driven decisions. As Ireland’s population continues to rise in line with the National Planning Framework, there is a need to ensure that transport infrastructure investment is undertaken to best meet the needs of our citizens.”
Some readers will know Strong Towns founder Charles Marohn. In a published extract of his book Confessions of a Recovering Engineer: Transportation for a Strong Town, rubbishes traffic models. I don’t think the NTA’s is open to all the criticism of the US models that Marohn is talking about.
But I understand that cycling — and more so the modal shift towards cycling — is a weak point of the NTA’s traffic model. This isn’t unique to Ireland, the European Cyclists’ Federation back in 2016 covered how “cycling often lacks in traffic models” and how an EU project aims to address this. There are some good reasons and other dubious ones why cycling isn’t included, especially when starting from an ultra-low modal share.
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Back in 2013, Rachel Aldred, now Professor of Transport at the University of Westminster, and the University’s Director of the Active Travel Academy, wrote: “I have been asking around about how transport models deal with cycling, to get a picture of where we’re at and what we want models for – rather than just including cycling in models for the sake of it, I was usefully reminded that we needed to ask what the purpose would be. Some people I’ve spoken to don’t think models should deal with cycling. When cycling rates are very low, any change can be drowned out in statistical noise. And cycling is locally variable. One person told me ‘I am suspicious of cycling modelling because propensity to cycle depends on so many local conditions.’”
I’m not even sure if the issue with Climate Action Plan Phase 3 Modelling Executive Summary report by the NTA is even the fault of the model, but rather it’s mainly explained by “lack of ambition in, lack of ambition out”. The modal is only as good as what data is is fed.
Just like computer programming from the early days of computers to modern machine learning, “garbage in, garbage out” also applies to traffic modelling. Any biases and incorrect presumptions will massively affect what’s modelled.
So, rather than “informed and data-driven decisions” we get models which are no more data-driven than machine learning is true artificial intelligence (ie not at all).
The Phase 3 Modelling Executive Summary report states:
“The Pathway assumes that cycling levels can double from their 2018 levels by 2030 and, based on an analysis of the NHTS, it has been estimated that doubling non-leisure-activity cycling trips will result in an additional 10% increase in overall walk and cycle trips and a 7% increase in overall sustainable trips (walk, cycle, and PT).”
What exactly is this presumption based on? It doesn’t seem to be any documented real-world experience.
There was a 160% increase in cycling into Dublin City Centre between 2004-2014. The investment and interventions in Dublin between those years were minimal compared to what’s happening now and what’s planned in terms of scale and funding. Yet the level of change was much higher:
With some effort across London, but still, with many council boroughs lacking, London is recording overall cycling levels in 2022 which are, according to Transport for London, 40% higher than pre-pandemic in 2019. Despite less commuting, the TfL data shows 20-25% more cycling on weekdays and around 90% more cycling at weekends. It’s only a two-year period but as per this Transport for London press release, it requires some concerted effort.
On Paris, Transport & Environment, an EU transport lobby group, pre-pandemic in early 2020 wrote: “The mayor’s office has published new statistics showing that bicycle use in both the centre of Paris and the suburbs rose by 54% in one year following a considerable increase in cycle lanes, many of them separated from motorised traffic.”
StreetsBlog reports the change in cycling levels in Paris as increasing by “250 percent from 2004 to 2019”. That website further reports that “Cycling levels in Paris increased sharply during the pandemic, with cycling levels about 60% greater in 2020 and 2021 than in 2019.”
With a massive €360 million budget for walking and cycling for Ireland’s 5 million people, and a focus on both climate action and the wider benefits of active travel, there’s no reason we cannot see a doubling of cycling levels in Ireland in 2-3 years rather than 7 years. But — again — that requires a concerted effort, especially in cities and larger urban areas.
But “garbage in, garbage out” doesn’t just apply to computing. Paris and London are making strong efforts on building not just routes but the bones of networks with higher standards than here.
As IrishCycle.com covered recently, the Liffey Valley BusConnects project is wake-up call for better design for walking and cycling.
Over a decade ago I was told by senior staff in National Transport Authority and councils that narrow cycle lanes were going to be a thing of the past. But now we are seeing the installation and planning of sub-standard width cycling infrastructure (under 2 meters and even 1.5 metres or under). International experts are warning that due to more cargo bikes, electric bicycle and e-scooters, 2 metres is no longer enough for unidirectional cycle tracks or paths.
Or continued use of narrow cycle routes is sometimes due to a reluctance to use more space-efficient two-way cycle paths, other times because a council is prioritising extra-wide traffic lanes or parking, and even due to designing pinch points for cycling when such designs are known to cause more conflict.
Both Paris and London are also making strong use of two-way cycle paths on streets which can help with providing better usable width.
A larger issue in Ireland is routes that give up at junctions — usually dumping people cycling into what otherwise looks like pedestrian space or mixing them with motor traffic… or often a contradictory mix of both. Connects that people need to make to schools, workplaces, shops etc are also often nonexistent, inconvenient or via shared crossings.
Even well after the UK is now getting side-road priority right in terms of following the basic idea that people walking and cycling on the main road should get priority over motorists turning in or out, Ireland is still lacking this clarity and a lack of priority is being built into even NTA-planned schemes.
The experiments in the Dutch city of Delft tells us that a connected network of routes — including cycle paths but also low-traffic streets — is needed to really see a transformation of the number of people cycling.
Cycling doesn’t just have to be safe, but also convenient, attractive, a social experience, and even fun. The lack of vision and ambition for this is striking in most current cycle route plans, including nearly all of BusConnects in Dublin, Cork, and Galway which hardly meet Irish standards of over a decade ago.
That’s before we get into the need for guarded bicycle parking at train stations and city centres, and other changes such as promoting cycling as attractive, convenient and, again, even fun — moving away from pushing high-vis and helmets down the throats of anybody thinking about cycling.
But even without fully addressing the lack of ambition, the modding presumptions seem conservative.