How traffic engineering standards can break our cities

Many of you will know me as just a facetious blogger who spouts off about random things from time to time. This is indeed true.

What is also true, however, is that in a previous life I worked as a transport engineer. While nowadays I work primarily as a transport planner and an economist (roles in which I have more of a policy focus), from time to time I still find myself getting down and dirty with the application of basic traffic engineering principles.

Over time these experiences have led me to form the opinion that the traffic engineering profession in New Zealand is, shall we say, pretty much broken. It’s broken largely because “standards” have been progressively used as a substitute for thinking. And we’ve basically chosen the wrong standards. We’ve chosen traffic engineering standards that 1) fail to acknowledge basic scientific/economic principles, such as minimum parking requirements and 2) prioritise vehicle mobility ahead of other more important socio-economic outcomes. Many of these standards have profoundly negatives impacts on our cities.

In this recent post Matt presented one case study of a road re-design in Washington, in which he contrasted the designs for a corridor put forward by traffic engineers versus transport planners. Needless to say the options presented by the latter (illustrated below) appealed more to all of us here at TransportBlog.

Washington Freeway replacement Planner options

Not only do the options developed by transport planners have greater aesthetic appeal, but three of them also provide for additional land use development within the transport corridor. Indeed, traffic engineering practises that are currently applied in New Zealand (and to a greater degree Australia) do not even stop and consider the value of land. Land is so dam valuable, and the efficiency with which we use it determines, to a large degree, the productivity and amenity of our urban areas.

It would not be too factitious to suggest that many traffic engineering standards seem to presume that land is free. It’s as is if there are dutch pixies at the bottom of the garden who are manufacturing land from the sea.

One example of such a standard is the concept of the “design vehicle”, which I will focus on for the remainder of this post. Of course there are many other examples of traffic engineering standards, such as minimum parking requirements, which have been discussed before on this blog and that also have hugely negative consequences. The reason I want to focus on the “design vehicle” concept is because it does not receive much attention. And also because it has a fundamental impact on so many things.

For those who are not familiar with the “design vehicle” concept let me briefly explain. The “design vehicle” is a phrase that typically describes the largest, heaviest (per axle), and/or least maneuverable vehicle that is expected to use a particular part of the road network. Naturally, the physical footprint required to accommodate this design vehicle subsequently defines most aspects of the physical road geometry, such as turning radii and pavement design. For this reason, the shape of our road networks is very much defined by the design vehicle that is chosen.

You can read up on some of the design vehicle standards recommended by the NZTA here. The design vehicle for the standard street is typically some form of medium rigid truck, such as what is commonly used to move furniture. I’ve illustrated the physical dimensions of this vehicle below.

Medium rigid truck

The choice of design vehicle can have a massive impact on the degree to which a particular road supports, or more commonly undermines, socio-economic outcomes in urban areas. Working with a large design vehicle effectively puts paid to the types of narrow lanes and tight intersections that are ubiquitous in European cities (as an aside I’m writing this from Amsterdam, having just traveled through Paris, Porto, and Barcelona). Here’s a photo of my bicycle and I in a narrow lane in Barcelona.

DSCN4527

Alternatively, if you can convince your traffic engineer to use a smaller design vehicle then you can reduce the physical footprint of the road network.

In my experience, however, the traffic engineering profession has developed a “gotcha” for anybody who dares suggest a smaller design vehicle be used. The “gotcha” is service vehicles, such as garbage trucks and emergency service vehicles. That’s right, the humble garbage truck, they argue, needs comprehensive access to every urban nook and cranny. In turn, our urban nooks and crannies are designed around the needs of the garbage truck, which is – perhaps needless to say – rather large.

In this way, it is actually relatively difficult to argue for tight lanes and turning circles in many new developments in Auckland, by virtue of the need to provide access for service vehicles. Now I would have less issue with this standard if someone, somewhere had actually sat down and considered what the benefits and costs of such a standard were. Typically, traffic engineering standards require more land, which is a cost. The benefit, I presume, is increased mobility. Hence it should be fairly straightforward to undertake some form of benefit-cost analysis of the regulation to work out

Now take a look at the photo below, which shows a relatively common streetscape from Amsterdam.

Compressed

You will notice a cycle lane running from the bottom left of the figure towards the right hand side of the figure. If you follow this cycle lane closely then you should be able to make out the back of a small vehicle that is parked in the cycle lane just outside the shop. This is, my friends, a rubbish truck.

Which brings me to the point of this post. Amsterdam, like many European cities, designs their urban areas to deliver a broad range of socio-economic outcomes, such as walkability. This in turn requires narrower lanes and tighter intersection footprints. In response, they have effectively had to “down-scale” their rubbish trucks.

In this way I think the traffic engineering profession in New Zealand and Australia has put the garbage cart before the community horse. More specifically, instead of designing the communities we want and then selecting the vehicles that can integrate with that design, we choose the vehicle first and subsequently design our communities around their needs. I suspect our approach is very, very economically inefficient insofar as it increases the physical footprint of the road network. Remember, in cities, space is always expensive!

Engineers versus … everyone else?

How do you define “optimal conditions” in a transport sense? The graphic below paints a stark difference in opinion on what constitutes “optimal conditions” for different professions:

LOS

Image from Patrick Kennedy, D Magazine, http://streetsmart.dmagazine.com/2014/11/07/age-of-enlightenment/

Now I’m both an engineer and an economist, so feel I have some insight into the motivation for whoever developed this graphic.

It highlights a very important issue: Engineers tend to measure performance using indicators that measure mobility, whereas economists tend to measure performance using indicators that measure value.

Now don’t get me wrong: I strongly believe that mobility has a value. I write this having just fanged up and down the northern motorway taking some visiting Australian guests to Tawharanui. But it’s not the only thing I value. Indeed, tonight I will take them to Fort Street for dinner at Ima’s.

I accept that what constitutes “optimal conditions” will change depending on the context, and that in some contexts mobility has a very high value. What I can’t fathom is why the transport/traffic profession have developed such simple and inflexible performance indicators to guide their work.

I’m going to say this right now: Level of service tells you *nothing* about what people value. Why? Because it’s measured independently of the costs associated with being able to move freely. We could, for example, enjoy great LOS if we bulldozed the entire city and replaced it all with twenty-lane motorways connecting to vast carparks, with the occasional office building or house dotted amongst the seas of asphalt. But I think it’s obvious that would be a really, really bad outcome for almost everything else that we value.

From an economic perspective, congestion in cities can be seen as a good thing. It’s an indicator that lots of people are using the city in lots of different ways – going to work, travelling to see friends or family, going shopping, visiting sports games or art museums etc. Congestion has costs, of course, but eliminating it entirely would be even more costly.

The difference between Traffic Engineers and Planners

We often deride traffic engineers for the road dominant nature of Auckland. Sometimes this can be a bit unfair as we know not all engineers are bad and the term is often be a bit of a catch all phrase for those involved in the road design process. So when I refer to traffic engineers I’m referring perhaps more to the people and processes that sees the focus on movement and storage of vehicles over a public realm that focuses on people, the type that an urban planner might try to deliver. This post from Greater Greater Washington highlights these opposing ideas perfectly. A freeway was closed along a section of the Anacostia River in Washington DC after a new and updated freeway bridge was built over the river and the old freeway bridge turned into a local road.

DDOT then conducted a 2014 study of options to replace the freeway segment. The study devised xis options, but all of them basically looked like near-freeways. While pedestrians and cyclists could cross to access the waterfront, and cars could turn on and off to nearby streets in some options, all of the options turned a huge expanse of pavement and empty grass into other huge expanses of pavement and empty grass, sometimes also with tour bus parking.

DDOT’s options still primarily focused around moving cars fast, and would all have created big empty spaces that would not create any actual sense of place and would be, at best, unpleasant to cross on foot.

Washington Freeway replacement Option 2

So basically a road and a few cycle lanes surrounded by likely a lot of not very useful green space (the option above even included underground parking under the road for almost the entire length). The other options were all variations of the same theme and this is exactly the same type of thing we would see here in Auckland – and are seeing with proposals to upgrade local roads e.g. Lincoln Rd.

Residents, led by Advisory Neighborhood Commissioner Brian Flahaven, were not happy with the narrowness of DDOT’s analysis. Instead, at Councilmember Tommy Wells’ urging, the Office of Planning stepped in to do a more open-minded study of how to use the space.

OP’s options still look at four-lane boulevards and even four-lane parkways, but with much more appealing designs like a big park next to and partly on top of the road:

These are just some of the options they came up with and include various versions of parks, and development options.

Washington Freeway replacement Planner options

What’s worth noting is that the planners options contained just as many traffic lanes as the traffic engineers options did due to the transport engineers making it a requirement. The post questions the need for it to be four lanes but what is clear is that there are some quite different thinking going on between those just responsible for the movement of vehicles and those who also consider people and the city as a whole.

In Auckland if we could get more of the latter and less of the former then we could end up with a fantastic city that still allows for a wide range of movement even for those that want to drive.

 

Fighting Traffic: The Dawn of the Motor Age in the American City

The ridicule of their fellow citizens is far more effective than any other means which might be adopted [to control pedestrians]. EB Lefferts, Automobile Club of Southern California (1927)

While not a 2012 release, one of my favourite reads this year was Fighting Traffic by Peter Norton. Norton is an industrial technology historian who in Fighting Traffic documents the emergence and ultimate acceptance of cars in American cities.

fightingtraffic

In a nutshell Fighting Traffic tells the story of how traditional streets where changed from a  place of social exchange, slow movement, and even children playing to become dominated by car movement. The fascinating part of the story was that this transformation did not happen without a concerted effort by the automobile industry. When first introduced to American cities, cars and their drivers were considered pariahs and held accountable for their actions. Local newspapers articles, cartoons and editorials depicted the automobile as a purveyor of death which included macabre imagery such as gravestones, weaping mothers, and the grim reaper. This was easy to understand since even as early as 1930 as many as 16,000 people were killed in automobile accidents every year, mostly pedestrians.

During the early days, automobiles were considered incompatible to city life and this concerned automakers. Through their local automobile associations the car industry went about to change the responsibility of road safety by placing the blame on pedestrians. This was achieved by public media safety programs, school indoctrination, and even street theatre. The most effective method for shifting the public perception was by ridiculing pedestrians. One way this was achieved was through introduction of the term ‘jaywalker’ which implied derisively to a country bumpkin-type (a ‘jay’). Any person not fully respecting the new ruler of the road would be given a card by local Boy Scouts describing their action as inappropriate, and branding them as a jaywalker. This action had the effect of changing social norms, so that eventually laws could be introduced to codify this new value system.

There were two other major contributers to this paradigm shift. First, was the role of engineering of city streets for efficiency. Where once city streets were chaotic and slow-moving, engineering practices such as signalisation allowed for cars to move smoothly and at higher speeds. While good for the car, this lead to increased travel speeds which made it difficult for people to cross the street. This was bad for street life but the activities were at least conducted within the tradtional street right of way.

The second major change was the introduction of the gas tax. This action was largely resisted by the automobile industry until they realised how they could use it to their benefit. By reforming legislation to ensure that gas tax would go exclusively to road capacity, it was supported by the car industry and quicky adopted across all the states. This had the effect of not only paving over significant portions of tradtional cities, it also funded the grandiose surburban motorways, interchanges and cloverleafs that surround most cities today. Perhaps most significantly, the gas tax helped to pass assumed “ownership” of both existing and new roads to the car drivers whose taxes had paid for them.

In addition to documenting this fundamental change in the concept of streets, Fighting Traffic also describes the demise of the streetcar in places like Los Angeles (hint: it’s not as simple as the car makers buying and dismantling the tracks). Also he details how the automobile companies played a big part in selling the modern day version of cities that ultimately became idealised for public consumption in the Futurama exhibit at the 1939 World’s Fair in New York. Even the notion of “America’s love affair with the car” was an invention that can be traced back to a specific television show, sponsored in part by GM, where it was intentionally written into the script.

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Futurama, the 1939-1940 World’s Fair exhibit by General Motors.

Fighting Traffic challenges the modern day notion of what streets and even cities “are for”. It also raises interesting concepts of social norms, language and the role corporate interests play in framing conventional wisdom. Whenever we post something on this blog about street design you can expect that someone will comment something to the effect of “streets are for cars”– it then becomes clear how successful this orchestrated campaign was.

Note: With a bit of good timing this short safety clip from New Zealand in 1952 titled Pedestrians or Jaywalkers? was published.

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New Zealand traffic safety campaign 1952