Traffic impact assessments: four brainworms that refuse to go away

How can we work, through transport impact assessments (TIAs), towards a better city? How can we do this when the inherited toolkit for TIAs is outdated, the City bureaucracy is stretched and design consultancies work for impatient developers for whom time really is money?

The Street Minds group did a great job unpacking these and other issues at the latest meeting hosted by Open Streets Cape Town. I was left, though, with an uneasy feeling. After almost thirty years as a transport planner it seems we are stuck, as Susan Handy has argued, on the same old roundabouts. Are we doomed to remain there or are we ready to move on?

This left me with four thoughts that are begging for more interrogation.

1.When we measure levels of service (LOS), what do we mean (and do we actually want to focus on it?)

Levels of Service

(From Maryland State Highway Administration)

The TIA process has at its core the assessment of traffic so as to make sure developments don’t detrimentally impact on existing movement patterns. Impact is measured through vehicle levels of service (LOS) (among other things). This idea of levels of service, which is widely used in South African transport planning, is rooted in the earliest freeway design manuals from the 1960s.

The LOS idea has unconstrained free-flowing vehicle movement as the ideal and everything else as some sort of failure. This dream of free-moving traffic may be appropriate for the freeway context but is this the metric by which we want to judge our city streets? Even aiming for some sort of more realistic LOS B or C for city streets in a very short peak period is problematic. Thinking about LOS ideals keeps our focus trained on the wrong sort of metric – comfort and alleviation of frustration for motorists only.

2. So what about LOS for pedestrians?

One counter to the focus on LOS for vehicles is to generate levels of service for pedestrians, but these, too are problematic. Instead of considering the multiple complexities of human movement, LOS for pedestrians treat humans as simply another ‘vehicle’ in urgent transit from A to B. Pedestrians though, unlike vehicles, move in far more complex, less constrained and multi-directional ways. Conscious human beings – unlike vehicles – come with a whole set of senses, vulnerabilities and needs. Designing for humans outside of vehicles requires design thinking well beyond the efficiency, density and comfort thinking embodied by LOS.

3. What should we be aiming for with TIAs?

It’s a well-established realisation in transport planning that adding road infrastructure is, at best, a short term “solution” to congestion. In the long term, additional road capacity simply exacerbates and fuels traffic growth by inducing traffic. Yet, as transport planners we operate with a sort of cognitive dissonance when it comes to traffic growth, knowing that adding road capacity is a short-term measure while expecting developers to contribute to new road infrastructure. Developers themselves often perpetuate the status quo, wanting to release bottlenecks near to their developments so as not to stimulate the ire of their tenants and give their developments a bad public rap. So we live in the realm of the short-term fix.

One way out of this is to require more sophisticated responses from developers and a practical possibility is the Travel Plan – an institutionalised, site-based travel demand strategy popular in the UK. But anything like this requires the City to really prioritise the long term over the short term and the greater good over the developers. Tricky even in a stable and well-resourced State.

4. What are we doing when we model traffic?

Barbarossaplatz, Cologne – Traffic Simulation from heyne on Vimeo.

There is something  seductive about traffic simulations. Instead of being stuck in traffic, we are hovering above traffic and it’s an inspiring, creative space. This is very useful for designers. But I am deeply wary of these tools; they need to be handled with care. They create what Donna Haraway calls “the God-trick” and with it there is a risk that these tools disconnect the designer from the lived human experience and the traffic engineering exercise. It’s exacerbated by the traffic engineer’s focus on vehicles and the quantification of movement. It’s not that traffic engineering doesn’t need traffic simulations, but that they don’t go far enough. We live with all five senses and feet firmly planted on planet Earth and we need to design that way too. Not hovering above the traffic like a seagull.

[Thanks to the Street Minds group for a great discussion and to Marco Gerretto, Marcela Guerrero Casas and Brent Smith for edit suggestions.]


Five ‘take-homes’ from a Masterclass on Transport Justice

Karel Marten’s recent University of Cape Town Masterclass  on Transport Justice was full of worthwhile justice philosophy fodder. However, the five significant ‘take-homes’ asked for something closer to home – a revolution in transport planning methods.

  1. Congestion is a problem of privilege.

The existence of traffic congestion is essentially a sign that road infrastructure is a success. The road network provides a far better service to travellers than any other transport system. To try and improve roads is to try and improve an already superior service further and so to favour those who are already far better served than travellers on other system.

  1. Reducing congestion/ improving road traffic speeds can show no direct link to improving the macro economy.

It just doesn’t.

We have relied on the idea that reducing traffic congestion is somehow a magic cure for an ailing economy. We have imagined that all we need to do is move things and people along a bit faster and – hey presto – the economy revives. This argument contains all sorts of assumptions which are, at best, contested and at worst, false hopes.

  1. Travel demand management is tinkering and, in the long-term, trivial

While travel demand management (TDM) can result in marginal reductions in travel demand, the suppressed demand for road space in urban areas is so great that any improvements to congestion due to TDM will be eroded by the release of suppressed demand for road space.

At best, TDM is a short term fix. At worst, it is a waste of money.

Travel demand management has a role to play, though, in improving the energy efficiency, and so reducing the environmental costs, of road traffic. Increasing the numbers of people in vehicles, for example, has substantial energy and costs savings for users

  1. Solving congestion is possible but politically unpalatable.

Even if traffic congestion is considered the problem, the only real solutions – congestion pricing and vehicle-use rationing – are deeply politically unpalatable. The real challenge for the transport planning profession is to acknowledge this and not shy away from telling the unpalatable truths to politicians and the public.

  1. Traditional transport planning processes are deeply problematic

Traditional transport planning is trying to solve the transport problem as if it is an urban utility systems problem, like water provision. This wouldn’t be so bad if people behaved like water molecules. But they don’t. If we are concerned about justice and fairness then we face a different set of questions from the ones which drove the traditional transport planning methods.

Indicators like ‘Level of Service’, congestion/capacity ratios, delay measures or cost-benefit analyses focus our attention on the speeds of vehicles, when the key issues that we need to address are about human access to opportunities.

Thinking about human beings first means thinking more about the ability of all kinds of people to travel (by whatever means). It broadens our possible toolkit beyond infrastructure and vehicles and traditional transport planning.

Thinking transport justice is not about a focus on people as an add-on or as an after-thought, says Karel Martens, it’s about completely new methodologies. We need transport planning processes which intentionally focus on those we serve, and this means starting afresh from the ground up.

Mommy PhD: The Downer

Shortly after finishing the PhD people starting telling me that it was really common to get depressed after handing in and “did I feel OK”? The answer was “yes!” I felt lighter than I had in over a year. How ridiculous to think I would be down. What is not to like about seeing long neglected friends and family, and having those languid lie-ins and aimless wandering through shops? That was the first ten days.
The second ten days were a bit less indulgent and involved settling ooooold invoices, catching up on doctors’ appointments, unpacking boxes left over from our move but still seeing friends, getting my hair cut and updating my wardrobe. How could I not like this?
After the second ten days I woke up one day feeling really low. For me “low” looks like ratty, joyless, aimless, forgetful and compulsive sugar eating. One Saturday morning I sat on the edge of the bed and mumbled to Rob: “I’m not in a great space.” And then I burst into tears.


I decided to get professional help. I was feeling, I finally realised, bereaved in some way. It made sense, the therapist reassured me. A huge presence in my life had fallen away. This PhD had been a constant companion for over six years, had structured my daily ritual, how and when I exercised and ate, my focus, who I did and didn’t spend time with, my interests, my reading, my way of thinking about the world. It had provided me with some of my identity, and perhaps most importantly it had given me permission to live in a particular way. In a way which was unusual for mothers. Who wouldn’t miss that?

“You are in free fall” the therapist said. “The ground has fallen from underneath your feet. It’s scary.  Question is, where do you want to land?” Where indeed?
Where do YOU want to land post-PhD?
PS. This is the last blog post of me blathering on about my PhD. Next blogging outing will be in a new format blog and about where I landed after that downer! See you on the other side.

Mommy PhD: Guilt

In the midst of PhD completion crisis management I felt Guilty all of the time. Guilty about the lack of order, the lack of time, energy, attention. Guilty about the toilet paper and cereal running out. (“Really” said the devil on my shoulder”, what kind of a mom does that?!”) and guilty about the outbreaks of frustration that would erupt from time to time and turn me into a whirling dervish of the not-so-saintly kind. White guilt, mothering guilt, working class guilt, I was capable if it all, in whatever shade or hue you wished to see.
Fast forward then to the end of my PhD studies when the light is clear at the end of the tunnel and the chaos is receding. What do I do? Do I start ticking off those (by now voluminous) mother-to-do lists and start feeling holy and self-satisfied?! Are you kidding, I help start up a very worthy but very time consuming NGO and I move house. Several people close to me asked:”are you mad?!” In a way, I was. I was so ingrained, so practiced, so habitually used to feeling guilty that I selected things to do which just perpetuated that feeling which had become “me”. But of course it wasn’t really me. So thanks to some wise counsel I am experiencing the giddy weird experience of paying bills on time, gardening, shopping and doing the Domestic Goddess thing. Strangely difficult for a recovering Guilt Martyr but quite fun when I allow it to be.

From Sea to Mountain: time to re-frame the City?


Concept Sketch for Foreshore development (1940) from Town Planning Advisors Report to the South African Railways and Harbours Board

Frame (2)

Photograph of Proposal B: Foreshore exhibitions 2017

One of the more visionary elements in the current Foreshore Proposals is the ‘eye’ which would frame a view of Table Mountain from the harbour-side and create an iconic picture, especially for visitors arriving at the port. The idea has echoes of the earliest concepts for the area found in the 1947 Cape Town Foreshore Plan drawings, which highlighted the vista of those arriving by sea.

Sea approach (2)

Artist’s impression of view from Maritime Terminal, from Cape Town Foreshore Plan (1948)

Planners at the time created an over-arching concept for the area with a Monumental Approach from the Harbour towards the City Hall, framed by the Mountain Amphitheatre. For the consultants in the 1940s the Foreshore area was a “…a National rather than a Department or Municipal asset” and the planning was a “…unique opportunity, never likely to recur, of investing Cape Town with the dignity that is appropriate to the ‘Gateway to South Africa’”.

Over the following decades sea arrivals dropped in importance compared to air arrivals, and the words “Gateway to Africa” fell out of step with how Cape Town imagined itself. It is interesting, then, to see that the current Foreshore proposals include cruise terminal ideas. Is it is time to revisit the sea-city connections and the tourism and city marketing possibilities that could bring?

Cruise terminal B (2)

Detail from Proposal B

Table Mountain and its sea approach is a widely loved, and globally known connected vista. As a City have not made much effort to frame it, physically or otherwise, in any meaningful way. In an increasingly competitive tourism environment can we afford to underplay the ‘romance’ of the approach by sea and the iconic vista that few cities can even aspire to? Or is the maritime ‘romance’ too associated with a European history many would rather forget? Could we find a way to physically re-frame this sea approach to Cape Town as part of Foreshore developments? In the process bringing forward the sea stories of all who sail and have sailed around the Cape, not only the wealthy few?




Dreams of freeway utopias: who benefits?

Futurama viewers

Viewing Futurama (Prelinger Collection)

In the Spring of 1937 Shell Oil Company employed stage designer Norman Bel Geddes, to create a scale model of the future, utopian auto city for shows in New York and Detroit. Shell promoted this model, dubbing it the ‘City of Tomorrow’. The head of the Bureau of Street Traffic Research predicted that American cities would be rebuilt in this way in the next 25-50 years. During 1939-40, General Motors (GM) put on a major exhibit at New York’s World Fair, commissioning the same Bel Geddes to expand his Shell model to much bigger proportions. They called it ‘Futurama’.

In the first summer of the Fair, more than 5 million visitors traveled on conveyor belts to look down on the GM ‘Futurama’ model exhibit, as if from an airplane window. In Futurama free movement of autos was evoked across vast panoramas. The film of the exhibit, ‘To New Horizons’ (1940), evoked an America where there was freedom from want, and where mobility – social and physical – meant movement in cars on free-flowing expressways.

In the 1940s South African engineers toured US highway engineering departments and in 1951 the Cape Town City Engineer’s department published ‘Metropolis of Tomorrow’. The document suggests that Futurama-style thinking was important to the South African engineers too.

Sixty-five years on, looking at the Foreshore exhibitions, I wonder: are we still dreaming of a South African Futurama where road space is abundant and a free-flowing utopia is possible? And if so, who benefits from such dreams?

20170308_141258 (3)

Detail from Proposal C


“Lean and elegant”: The poetics of freeway building

Graphic from Proposal B

Graphic from Proposal C

“Our proposal starts”, said one of the Foreshore bids “by re-arranging and completing the elevated freeways in a lean and elegant way, thereby resolving the key traffic bottlenecks and improving traffic flows all across the surrounding road network.”

‘Lean’, ‘elegant’ and the resolution of traffic bottlenecks is not text-book civil engineering, but these words do evoke a long poetic tradition in traffic engineering texts.

When the first high speed roads for the foreshore were proposed by City Engineer Solomon Morris in 1951 they included a plan to depress part of a ring road across Government Avenue.

Morris wrote: “The bridges will be sympathetically designed in keeping with their sylvan setting, whilst the terraces and rockeries forming the banks will be planted with shrubs and other flowering plants so that no interruption or disturbance of the garden effect takes place…Indeed there is no reason why these proposals, if effectively carried out, should not enhance rather than detract from the beauty of the gardens and the Avenue promenade. The new vistas and the additional interest created by the difference of level, as well as the movement of traffic below the level of the gardens, will all help to enliven the scene, adding a touch of activity to the peaceful beauty of the surroundings. One may well imagine the pleasurable contemplation with which the passer-by through the Avenue will, from the quest seclusion of his elevation, gaze undisturbedly on the swift-moving traffic below.”

1951 Government Avenue

From: Metropolis of Tomorrow, 1951

Sylvan settings, lean and elegant roads, pleasurable contemplations, new vistas and gazes….Despite the use of scientific rationality and logical connections traffic engineering is, ultimately, about planning for the future. Planning, as Throgmorton has so memorably argued, is the art of persuasive story-telling. And as we can see from the texts it produces, engineering will try to persuade using whatever means have most power: numbers, graphics, models, presentations and even, if required, poetry.

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