Transport planning plays an outsized role in shaping the future of our metropolises. Land use and the daily activities of residents depend on transport and the access it provides. Transport only exists to serve activities people want to engage in. Growing cities naturally want to expand transport infrastructure. Because transport takes a long time to develop and deploy, and tends to be irreversible, it is worth some effort to try to get it right.
I think the reductionism of the model, as an input to a fantasy business case, is nearly pointless. Because the assumptions put in the model invariably reflect the outcome that the business case and model are desired to provide. That is, we have taken so called scientific approaches to provide rationalism to balance the visioning, but then manipulated them to validate the vision. And many of us have lived the announced project which becomes a real thing long after the minister has expired from the role, at billions, which is retrospectively put through the sausage machine, which proves wholeheartedly the entire system is flawed. Not in concept, but in practice. The model, after all, is only meant to point to areas that require investigation. It is a less than 1 per cent network replication. But there are fools who quote the model as though it was something real and tangible. All models rely on assumptions to guide them. And all assumptions are resolutely human, are typically optimism biased and are very open to manipulation for a tendentious result. We can build a 10 per cent simulation of any complex network of networks relatively quickly and cheaply now. But the future state simulation is still subject to agreed assumptions!
While the critique is valid and warranted I'm left thinking of the famous quote popularized by Churchill, "predict and provide is the worst form of transport planning except for all the others."
Mind you this comes exclusively from a North American perspective, but the fatal flaw in "envision" model is the inherent irrationality of man and the prevalence of spoken vs revealed preference.
The satirical news site The Onion had this nailed 20 years ago with the famous piece "Report: 98 Percent Of U.S. Commuters Favor Public Transportation for Others". We see this replicated with the wild disparity between polling preference for bike infrastructure in general vs bike infrastructure that in any manner affects the driving and parking conditions of each individual respondent. The community vision many if not most practitioners get in the States is a city of single fam homes within walking distance of rail and free parking wherever I "need" to get in a car. Without some form of modeling to demonstrate the abject impracticality of such things you're left in a p*ssing match of ideologies.
Any "envision" model that substantially deviates from the type of status quo that informs predict and provide must be led by massive changes in land use and taxation in order to have any chance at being effective. This is easily solved in an academic setting, but I've yet to see one single Planning Director with the political clout to pull it off.
Slightly off topic, but what are your thoughts of small-scale models, such as intersection modelling? The results of these models are also important, and will influence road space allocation decisions at a local level. For example, space will generally only be reallocated for pedestrians, bikes or transit if the modelling says there will be no material effect on traffic flow as a result.
More understandable. The issue are the embedded values (minimizing vehicle delay rather than prioritizing access for active travelers, or even minimizing person delay) and the assumptions of static demand (understandable for a single intersection, but it can’t be added up). Of course there are few pedestrians if the road is hostile to pedestrians. Is that what we want?
Under the given inputs around values and goals of a project, a number of options for potential solutions can be possible (particularly with complex junctions and urban plazas) - this is where microsimulation can be quite insightful to the (strategic) transport planners themselves.
Besides that, transport planners who both share human-oriented values and have a lot of practical experience with traffic management might be able to solve most problems with paper and pencil, but as any other urban professionals they are expected to communicate their ideas to the external world. This is where microsimulation, particularly video outputs of such, is definitely helpful.
And, ultimately, - yes, decision-making rooms are always full of people who do not understand cities, human interactions, and public space, and are only interested in vehicular traffic 'levels of service'. Delivering projects requires being able to have meaningful conversations with these people, too.
The first: What is your evidence of this super planner who is so effective "in shaping the future of our metropolises"? Most transport planners I know complain bitterly that no one listens to their advice and that most decisions are made for political reasons. If you have evidence that shows my colleagues are wrong I'd be pleased to this share them with them. Obviously, I'm hanging out with a bunch of losers.
The second: The work of Flyvbjerg (another frustrated planner) and others would suggest that models are used not to inform decision-making but rather are rationalisations of decisions made by other means. Take for example Victoria's Suburban Rail Loop (the largest infrastructure project in the country). Detailed modelling was only undertaken for this project AFTER it was announced as a government priority. I can offer many other examples.
The third (OK three things come to mind): Normative transport planning places modelling in a far more limited context than you acknowledge. The first step of normative planning is one of problem (or opportunity) identification and strategic fit. Not only does a problem need to exist (and can be defined), but it must shown to be a problem that our strategic plans indicate is worthy of resolution. The second step is the identification and shortlisting of options to solve the problem. It is only in the third step that the detailed models you describe are used to assess the shortlisted options to determine a preferred project. In this normative world, models are used very selectively to evaluate a limited number of possibilities all of which tend to be variations on a theme. It is perhaps worth having a read of the ATAP guidelines.
I know many planners and modellers (the two are very different beasts) get excited about transport models but in my experience, the main game is being played on a very different field.
1. I gave an either or. Either they are used or they are not. If they are not, why do it. If they are, the outcomes are terrible. Obviously there is something in the middle, they are sort of used and the outcomes are only sort of terrible.
2. Clearly on mega-projects, the outcomes are fore-ordained, then why even try to do the rationalisation? [For political reasons, a profession should not be weapons-polishers for the politician] On smaller projects, they probably have more effect.
3. I don't think so (obviously). Rational planning as you describe is not what actually happens. All too often the solution is identified, and models are used to justify it.
But my main point is the time frame. No one can forecast 40 years out, why do we pretend to? (Similarly, why do we plan 40 years out?) The only possible value is preservation of contiguous rights-of-way for future infrastructure, and we don't need models (or much in the way of plans) to preserve future options.
The planners I work with don't pretend to know the future. What they do is create scenarios and assess options under various scenarios in order to influence project outcomes.
Consider the Melbourne Metro project - a project I have worked on. A key design question was how much extra capacity should be provided in the initial design. Current policy is to encourage public transport use and population growth so it follows that major infrastructure should "lean forward" and provide space to grow (strategic fit). Yet providing capacity underground is expensive but retro-fitting it is even more expensive. To address the question of how much capacity should be provided modelling was used to inform the decision - scenarios of population growth, mode shift, network expansion and other factors, were developed and translated into a range of ridership projections (not forecasts). Various design options were then created including train size, passenger density and train throughput to match capacity and demand under different scenarios. These options were then assessed (cost, environmental impacts, feasibility etc.) to inform the decision-making process - in the end a finite amount of extra capacity was provided that would address a number of future scenarios but not all. It was something of a rational process.
I know in other projects those involved could guess or "envision" an answer but I'm yet to be convinced that this is a better form of planning.
My concern is that demonising planning models through strawman arguments weakens planners' ability to influence outcomes. The problem is not with the models but with how they are understood and perceived. And I acknowledge many planners contribute to this problem.
They who use the model outputs as "evidence" and dismiss all else are not all fools. Some are acting effectively in the service of their masters and are rewarded with promotion. I saw this with the bankrupted Brisbane toll roads. Also in NZ much of the policy looks good but the use of modelling here to fulfil ambition on big projects with little regard for reality is rife.
I think the reductionism of the model, as an input to a fantasy business case, is nearly pointless. Because the assumptions put in the model invariably reflect the outcome that the business case and model are desired to provide. That is, we have taken so called scientific approaches to provide rationalism to balance the visioning, but then manipulated them to validate the vision. And many of us have lived the announced project which becomes a real thing long after the minister has expired from the role, at billions, which is retrospectively put through the sausage machine, which proves wholeheartedly the entire system is flawed. Not in concept, but in practice. The model, after all, is only meant to point to areas that require investigation. It is a less than 1 per cent network replication. But there are fools who quote the model as though it was something real and tangible. All models rely on assumptions to guide them. And all assumptions are resolutely human, are typically optimism biased and are very open to manipulation for a tendentious result. We can build a 10 per cent simulation of any complex network of networks relatively quickly and cheaply now. But the future state simulation is still subject to agreed assumptions!
This is a brilliant summary of what is a huge crisis in the industry that very few people seem to openly recognise.
While the critique is valid and warranted I'm left thinking of the famous quote popularized by Churchill, "predict and provide is the worst form of transport planning except for all the others."
Mind you this comes exclusively from a North American perspective, but the fatal flaw in "envision" model is the inherent irrationality of man and the prevalence of spoken vs revealed preference.
The satirical news site The Onion had this nailed 20 years ago with the famous piece "Report: 98 Percent Of U.S. Commuters Favor Public Transportation for Others". We see this replicated with the wild disparity between polling preference for bike infrastructure in general vs bike infrastructure that in any manner affects the driving and parking conditions of each individual respondent. The community vision many if not most practitioners get in the States is a city of single fam homes within walking distance of rail and free parking wherever I "need" to get in a car. Without some form of modeling to demonstrate the abject impracticality of such things you're left in a p*ssing match of ideologies.
Any "envision" model that substantially deviates from the type of status quo that informs predict and provide must be led by massive changes in land use and taxation in order to have any chance at being effective. This is easily solved in an academic setting, but I've yet to see one single Planning Director with the political clout to pull it off.
Slightly off topic, but what are your thoughts of small-scale models, such as intersection modelling? The results of these models are also important, and will influence road space allocation decisions at a local level. For example, space will generally only be reallocated for pedestrians, bikes or transit if the modelling says there will be no material effect on traffic flow as a result.
More understandable. The issue are the embedded values (minimizing vehicle delay rather than prioritizing access for active travelers, or even minimizing person delay) and the assumptions of static demand (understandable for a single intersection, but it can’t be added up). Of course there are few pedestrians if the road is hostile to pedestrians. Is that what we want?
You wouldn't have thought so, but we sure do act like it!
Under the given inputs around values and goals of a project, a number of options for potential solutions can be possible (particularly with complex junctions and urban plazas) - this is where microsimulation can be quite insightful to the (strategic) transport planners themselves.
Besides that, transport planners who both share human-oriented values and have a lot of practical experience with traffic management might be able to solve most problems with paper and pencil, but as any other urban professionals they are expected to communicate their ideas to the external world. This is where microsimulation, particularly video outputs of such, is definitely helpful.
And, ultimately, - yes, decision-making rooms are always full of people who do not understand cities, human interactions, and public space, and are only interested in vehicular traffic 'levels of service'. Delivering projects requires being able to have meaningful conversations with these people, too.
Dave, two thoughts come to mind.
The first: What is your evidence of this super planner who is so effective "in shaping the future of our metropolises"? Most transport planners I know complain bitterly that no one listens to their advice and that most decisions are made for political reasons. If you have evidence that shows my colleagues are wrong I'd be pleased to this share them with them. Obviously, I'm hanging out with a bunch of losers.
The second: The work of Flyvbjerg (another frustrated planner) and others would suggest that models are used not to inform decision-making but rather are rationalisations of decisions made by other means. Take for example Victoria's Suburban Rail Loop (the largest infrastructure project in the country). Detailed modelling was only undertaken for this project AFTER it was announced as a government priority. I can offer many other examples.
The third (OK three things come to mind): Normative transport planning places modelling in a far more limited context than you acknowledge. The first step of normative planning is one of problem (or opportunity) identification and strategic fit. Not only does a problem need to exist (and can be defined), but it must shown to be a problem that our strategic plans indicate is worthy of resolution. The second step is the identification and shortlisting of options to solve the problem. It is only in the third step that the detailed models you describe are used to assess the shortlisted options to determine a preferred project. In this normative world, models are used very selectively to evaluate a limited number of possibilities all of which tend to be variations on a theme. It is perhaps worth having a read of the ATAP guidelines.
I know many planners and modellers (the two are very different beasts) get excited about transport models but in my experience, the main game is being played on a very different field.
1. I gave an either or. Either they are used or they are not. If they are not, why do it. If they are, the outcomes are terrible. Obviously there is something in the middle, they are sort of used and the outcomes are only sort of terrible.
2. Clearly on mega-projects, the outcomes are fore-ordained, then why even try to do the rationalisation? [For political reasons, a profession should not be weapons-polishers for the politician] On smaller projects, they probably have more effect.
3. I don't think so (obviously). Rational planning as you describe is not what actually happens. All too often the solution is identified, and models are used to justify it.
But my main point is the time frame. No one can forecast 40 years out, why do we pretend to? (Similarly, why do we plan 40 years out?) The only possible value is preservation of contiguous rights-of-way for future infrastructure, and we don't need models (or much in the way of plans) to preserve future options.
The planners I work with don't pretend to know the future. What they do is create scenarios and assess options under various scenarios in order to influence project outcomes.
Consider the Melbourne Metro project - a project I have worked on. A key design question was how much extra capacity should be provided in the initial design. Current policy is to encourage public transport use and population growth so it follows that major infrastructure should "lean forward" and provide space to grow (strategic fit). Yet providing capacity underground is expensive but retro-fitting it is even more expensive. To address the question of how much capacity should be provided modelling was used to inform the decision - scenarios of population growth, mode shift, network expansion and other factors, were developed and translated into a range of ridership projections (not forecasts). Various design options were then created including train size, passenger density and train throughput to match capacity and demand under different scenarios. These options were then assessed (cost, environmental impacts, feasibility etc.) to inform the decision-making process - in the end a finite amount of extra capacity was provided that would address a number of future scenarios but not all. It was something of a rational process.
I know in other projects those involved could guess or "envision" an answer but I'm yet to be convinced that this is a better form of planning.
My concern is that demonising planning models through strawman arguments weakens planners' ability to influence outcomes. The problem is not with the models but with how they are understood and perceived. And I acknowledge many planners contribute to this problem.
They who use the model outputs as "evidence" and dismiss all else are not all fools. Some are acting effectively in the service of their masters and are rewarded with promotion. I saw this with the bankrupted Brisbane toll roads. Also in NZ much of the policy looks good but the use of modelling here to fulfil ambition on big projects with little regard for reality is rife.