Wednesday, 6 February 2013

Confessions of a traffic engineer: Is the need for speed killing us?

Dean Cracknell is the author of this post. He is a Freo devotee interested in creating diverse places for people. He is a guest contributor to The Fremantle Doctor blog. Dean can be followed on Twitter by checking out: @city_pragmatist

I'll cut to the chase. Placemaking champion, Fred Kent, from the Project for Public
Spaces, says it far better than I could ever do:

"If you plan cities for cars and traffic, you get cars and traffic. If you plan for people and places, you get people and places."  

"It is not true that more traffic and road capacity are the inevitable results of growth. They are in fact the products of very deliberate choices that have been made to shape our communities to accommodate the private automobile. We have the ability to make different choices — starting with the decision to design our streets as
comfortable and safe places — for people on foot, not people in cars."

This post is about priorities and the choices we make. Our priorities say a lot about who we are as individuals and as a society. Fred Kent highlights in flashing lights the choice we have all made (whether we know or not) to design our cities around cars.

Charles Marohn, a self-confessed recovering traffic engineer (love that description), reveals the priorities of his former profession on his Strongtowns blog (click here). Charles reckons that engineers have a very unhealthy need for speed. His insights make for interesting and powerful reading and I thought that I’d share some of his confessions with Freo Doctor readers.

(I’ve italicised quotes from the article below.)

The Priorities of a Traffic Engineer

“An engineer designing a street or road prioritizes the world in this way, no matter how they are instructed:

1.         Traffic speed;
2.         Traffic volume;
3.         Safety;
4.         Cost.

The rest of the world generally would prioritize things differently, as follows:

1.         Safety;
2.         Cost;
3.         Traffic volume;
4.         Traffic speed.

In other words, the engineer first assumes that all traffic must travel at speed. Given that speed, all roads and streets are then designed to handle a projected volume. Once those parameters are set, only then does an engineer look at mitigating for safety and, finally, how to reduce the overall cost (which at that point is nearly always ridiculously expensive).

We go to enormous expense to save ourselves small increments of driving time.”

Jeez, talk about misplaced priorities. In another article (click here), Marohn explains that a 40 second reduction in his typical commute time costs his community $107,000!

I value my time, but for me safety is more of a priority. I reckon that our schools, hospitals and community services would be more than grateful to receive an increase in funding at the expense of saving a few minutes of commuting time.

Blame It On The Romans

Where does this need for speed come from?  Looks like it has something to do with the Ancient Romans:

“Some of our craft descends from Roman engineers who did all of this a couple of millennia ago. How could I be wrong with literally thousands of years of professional practice on my side? Of course the people who wrote the standards knew better than we did. That is why they wrote the standard.

When people would tell me that they did not want a wider street, I would tell them that they had to have it for safety reasons.

When they answered that a wider street would make people drive faster and that would be seem to be less safe, especially in front of their house where their kids were playing, I would confidently tell them that the wider road was more safe, especially when combined with the other safety enhancements the standards called for.

When people objected to those other "enhancements", like removing all of the trees near the road, I told them that for safety reasons we needed to improve the sight distances and ensure that the recovery zone was free of obstacles.

In retrospect I understand that this was utter insanity. Wider, faster, treeless roads not only ruin our public places, they kill people. Taking highway standards and applying them to urban and suburban streets, and even county roads, costs us thousands of lives every year. There is no earthly reason why an engineer would ever design a fourteen foot lane for a city block, yet we do it continuously. Why? The answer is utterly shameful: Because that is the standard.”

The need for speed could be killing us! Serious stuff.

What Does This All Mean for Perth?

With Charles’ confessions in mind, let’s check out some streets in Perth and ask ourselves which one a motorist is more likely to speed along.

Case study 1

Photo A

Photo B
Photo A is the obvious culprit. As a wide, treeless road, it has been designed with little other than speed in mind. Our collective priorities are clearly evident to anyone who wants to notice them.

On the other hand I wouldn’t be speeding (if I were to hypothetically do such a thing ...) along the more intimate, little street shown in Photo B. Why? For me, it’s the uncertainty. The street isn’t wide and the parked cars have the effect of making it even less open. If I’m uncertain, I wouldn't throw caution to the wind and put my foot down. It could be dangerous.

Case study 2

Photo A

Photo B
This case study compares different views of the same place - Scarborough Beach Road in Mount Hawthorn. The photos have been taken about 100 metres apart looking in different directions.

As in the first case study, Photo A is the obvious culprit for encouraging motorists to speed. Wide lanes. No trees. No people. Driving along this part of the road, it’s difficult for any motorists to do anything but speed.

Photo B presents differently. The road is not as wide. There is definitely more going on that could make a motorist feel uncertain. Speeding on this part of Scarborough Beach Road is not only less likely, but something I never witnessed on dozens of visits as a nearby resident.


Thinking about Scarborough Beach Road with Charles Marohn’s and Fred Kent’s words in mind, I’m convinced that they’re onto something. Speed must not be the priority when we design our roads and, if we plan for cars, then traffic is what we’ll get (and what we'll deserve).

Hugh Newell Jacobsen said it brilliantly way back in 1929 - “When you look at a city, it’s like reading the hopes, aspirations and pride of everyone who built it”. In other words, it's our collective priorities that we see before us every day.

If I was to take Hugh Newell Jacobsen for a stroll along Scarborough Beach Road, I would ask him what he would read into our hopes, aspirations and pride of our city. I’d also ask him what he thought our community valued most. People or cars?

I don’t think I’d be surprised by his answers. I think it’s time to change our priorities.
Before I go, I'll leave Freo Doctor Blog readers with some sobering stats:

- Australian road toll in 2012: 1,300 people. (Click here to go to the document.)

- Australia has one of the highest urban speed limits in the world. A reduction of 10 km/h in travel speed would prevent 50% of all pedestrian fatalities and 21% of all collisions. (Click here to go to the document.)


  1. Good one Dean - I like the photos too.

  2. Excellent post. Thanks for sharing it.

  3. 'Walking is Not a Crime'

    Another interesting article related to the above post. Check it out at -