viernes, 2 de diciembre de 2016

The Pasanen Report

(Versión española aquí)

Anyone who has a friend who is in favor of the theory of "vehicular cycling" knows the Pasanen Report, either by its name "The risks of cycling", or as "the report that proves that cycle paths are more dangerous than the carriageway ". The Pasanen Report was written in 2001 by Eero Pasanen, an engineer from the Helsinki Transport Department and a black novels author. Its main thesis is that "it is safer (for cyclists) to ride along carriageway, between cars, than through ours (refers to Helsinki) bi-directional cycle paths". After complaining that "it is hard to imagine that our present two-way cycling network could be rebuilt", Pasanen adds "But in those countries and cities which are just beginning to build their cycling facilities, two-way cycle paths should be avoided in urban street networks."

It is not surprising that supporters of vehicular cycling, which state that cycle paths are more dangerous than the carriageway, and should therefore be discarded, have the Pasanen Report amongst its texts of reference.

But does this report resists a critical analysis? The bulk of his argument is summarized in the attached figure, which compares the cyclist accidents that occurred in different scenarios:

The figure compares the total length of cycling trips on different ways (in blue) with the number of accidents recorded on those ways (in yellow), all in percentages. Apparently, the image shows that the percentage of cycling accidents on the cycle paths along the streets of Helsinki is higher than their share of the total of cycling trips. From where Pasanen deduces that it is more probable to suffer an accident while circulating on a cycle path than while circulating on the carriageway. 

A first methodological criticism to the Pasanen Report and its conclusions is that it is what is referred in social sciences as a "cross-sectional study", that is, a study that compares events taking place simultanesously. However, this is not the most appropriate method for the present purpose. In fact, it can be assumed that bicycle paths were built on the most dangerous avenues, in order to reduce their danger for cyclists. So, we do not know if the supposed higher danger of bicycle paths is simply due to the higher danger of the street itself. It would have been much better to do a "longitudinal study", comparing the accident rate on a particular route before and after building the cycle path. In this way, it would be possible to know with certainty its effect on cycling accident rate, irrespective of uncontrollable factors, such as the danger of the street itself (due, for instance, to a higher or lower traffic density).

But the main criticism refers to the classification of roads and, in particular, to the distinction between "separated" and "not separated" cycle paths. If we consider all the cycle paths together, we see that the total length of the bicycle trips on them is 45 + 26 = 71%, while the total number of accidents is 56 + 8 = 64%, and the comparison is favorable. The "separated" cycle paths account for 26% of the length of the bicycle trips and only for 8% of accidents. Therefore, to "rebuild" the Helsinki cycling network, improving their safety, does not seem as difficult as Pasanen claims: It would suffice to separate the bicycle paths from the carriageway by some physical elements, such as bollards or curbs.

Eero Pasanen also worried in his report about the competition that cycling does to public transport, a competition that is also seasonal in Helsinki (there are many more cyclists in summer than in winter). It is a specific problem of cities with an extreme climate, such as Helsinki. But it has nothing to do with the thesis of the dangerousness of the cycle paths relative to the carriageway, which Pasanen wields as the core of his argument.

The Pasanen Report dates from 2001 and does not seem to have had too much influence on the city's mobility policy. Helsinki is preparing to organize the Velo-city Conference in 2019, and plans to reach 17% cycling mobility by 2025.

jueves, 1 de diciembre de 2016

The future of electric mobility (II) Tonnes or kilograms?

(Spanish version here)

At the beginning of my previous entry on this subject I related an image of the Tour de France in which a motorbiker of the organization records with an infrared camera to some cyclists escaped from the peloton. The motorbiker was looking for possible batteries and electric motors that would help the cyclists to continue their adventure. It is not science fiction: a cyclist develops a power of only a few hundred watts and some hundreds more provided at key moments (on a ramp, for example) can to turn any mediocre cyclist into a superclass at the height of Indurain or Eddy Merckx. The current technology of batteries and electric motors allows to do so and it is not easy to detect, given the small dimensions of the batteries and the motors involved.

Does this mean that the future of electric mobility is the electric doping of cyclists? Of course not. But the above example is relevant because it shows what can be done by applying modern electric technology to a bicycle. Which can lead us to analyze the possible applications of this technology to a conventional bicycle.

Let's first calculate the weight of a lithium battery with an energy density similar to modern Tesla batteries of 0.5 kw-h per kg able to meet the needs of a cyclist riding an electric bicycle at 25 km / h, with an energy consumption of 250 watts, which is the legal limit for a pedelec (1). For an autonomy of 100 km (that would be traveled, at 25 km/h, in 4 hours), we would need an energy of 4x250 = 1,000 w-h = 1 kw-h. So if the energy density is 0.5 kw-h, the Tesla battery would weigh about 2 kg. A very accessible weight for your bicycle transport.

What power would we need to charge the battery? If we want to charge it in a minute (assuming the battery will withstand such a load, which with the current technology is impossible) we would need 60 kw of power, which is much more than any domestic installation can withstand. But if we settle for charging it in an hour, we only need 1 kw of power, of course. That is, we need what any domestic electric heater spends (2). So, while we still can not power our electric bike with electro-gas stations, at least we can say that the electro-stables we need are everywhere: any domestic plug is enough to "graze" our electric bicycle in a reasonable time.

In fact, all the above considerations (and many similar ones) can be made simply from the comparison between the power developed by a car (in the order of tens of thousands of watts) and a bicycle (of the order of hundreds watts), ie 100 times less. What makes thet a "slow" recharge of an electric bicycle can be done in 10 times less time and with a power 10 times less than the "slow" recharge of an electric car.

In addition, the use of the electric bicycle, which we must not forget that it is an assisted pedaling vehicle. Therefore, it requires some physical effort on the part of its driver. Thus, the pedelec need its own driver also doing from time to time stops to replenish forces. That is to say, the need to "graze" (electrically, it is understood) from time to time the electric bicycle, runs in parallel with the own needs to replenish forces of its driver. In a country with a minimally developed electrical infrastructure, both needs can be covered simultaneously almost anywhere (including the user's own home) without special electrical power or parking space needs.

So, we can conclude that although it is practically impossible to replace a conventional gasoline car with an electric one without drastically reducing its performance and/or facing problems of quite improbable solution (see my previous entry), with the electric bicycle just the opposite happens: Replacing a conventional bicycle for an electric bicycle means to significantly increase its performance, without creating problems whose solution entail relevant inconveniences.

So, unlike the electric car, the electric bicycle may already be a commodity of mass consumption. In fact it already is, and it is enough to go outside and take a look to be convinced of it. For those of us who, like me, believe that things do not happen by chance, there is no better confirmation of what has been exposed so far than the undoubted success of the electric bicycle around the world. In Western Europe and the US more than one million electric bicycles a year are sold, but that is nothing compared to China, with a fleet of more than 100 million (sic) electric bicycles and an annual output that exceeds 20 million (3). Conversely, global sales of electric cars are not expected to exceed 500,000 units this year.

Together with pedelecs and e-bikes, electric scooters, segways and "electric wheels" are undergoing a major boost as consumer goods. They all have the common denominator of being low-consumption vehicles (a few hundred watts at most) designed for personal transport. In fact, if we stop to look a little, many of the "electric cars" that we see for our cities and that are counted as such in the statistics, like the Renault Twizy, are actually four-wheel electric mopeds, that can be driven with a moped license.

Personally I feel that the commercial success of all these e-bikes, mini-electric cars, segways, etc., is due more to the little social consideration that physical exercise has as a daily activity in our motorized societies (4) than to its actual advantages. In any case, all these new and successful vehicles, including pedelecs, are personal transport vehicles of low weight and power (compared to a conventional car), low speed, etc. These characteristics completely alienate them from the ideal of the "electric car" (as a substitute for the conventional gasoline car). This allows them to take advantage of all the potential of emerging technologies in the fields of new materials (light and resistant), miniaturized electric motors , batteries, etc. Without facing the insoluble problems (because of their fundamental and not merely technological nature) that are faced when we attempt to replicate, based on electricity, the performances of a conventional gasoline car. In fact, this is what has almost always happened in the history of technological development: new technologies rarely replace old ones, but overlap with them, generating new paradigms.

Thus, these new electric vehicles, light and for personal urban transport, do not replace the conventional car, but rather appear as a new type of mobility, essentially urban. This new electric mobility could replace, improving their performance or even making it possible to generalize (for example in cities with large slopes), the urban mobility by bicycle, wherever it exists. This is something that even advertising, that great indicator of social trends, teaches us, as can be seen in the attached image, which corresponds to an advertisement of the aforementioned Renault Twizy.

This emergent electric mobility, personal and urban, will have positive and negative aspects. It will all depend on how it is run, whether towards a model that tries to replicate the conventional mobility of gasoline cars (mini-electric cars seem to be the paradigm in that sense) or towards a model inspired by active mobility, whose paradigm would be the pedelcs. Europe, partly due to the early pressure of groups such as cycling associations, seems to be heading in the second direction, encouraging pedelcs. Albeit, unfortunately, simultneously promoting the mirage of replacing conventional gasoline cars and buses by their electric counterparts, which get the lion's share of aids and investments.

The irruption of this new electric mobility will also have important repercussions in the regulatory field, similar to the one that had the irruption of gasoline mopeds in Holland in the years 70 and that caused not a few debates. For example, where should segways, e-bikes, or electric scooters should circulate? By the road or by the pedestrian zones? By bicycle paths? These issues are already here and depending on how they were solved reality will move in one direction or another. In principle, the position of cycling associations is that only those gadgets which - like the pedelecs - are an aid to active mobility, but do not replace it - such as e-bikes - can be equated with bicycles and should share the same regulation.

In any case, I am increasingly convinced that the future of autonomous (ie powered by batteries) electric mobility will go in the direction of the development of a new personal mobility of urban scope, whose first babbling we are already seeing. It would be good for us to prepare ourselves for it and at the same time stop pursuing the mirage of replacing our old and polluting gasoline cars with brand-new electric cars with equal benefits.


(1)  According to European legislation, an electric bicycle is an assisted pedaling vehicle (without accelerator: the engine starts when pedaling is detected and stops when it stops) with a maximum power of 250 and a maximum speed of 25 km/h. Above these performances, the vehicle is considered to be an electric motorcycle.

(2) Incidentally, using electricity to warm up (eitherour food or our feets on a stove) is very bad business, as the efficiency of the electrical system is only 1/3, which means that to produce 1 kw-h of thermal energy, we need (and pay) 3 kw-h of primary energy.

(3) This is due, in part, to the fall in sales of mopeds as a result of the restrictions on their circulation that have been imposed due to the increasing pollution of cities. It must be said anyway that most Chinese "electric bicycles" are, in fact, e-bikes or low-power electric mopeds, without pedals and equipped with an accelerator. They are therefore not pedelecs and, therefore, there are not electric bicycles in accordance with European legislation.

(4) Intensely motorized societies maintain a love / hate relationship with physical exercise. On the one hand, as an activity linked to everyday tasks - such as work, daily displacement, etc. - is considered as an indicator of low social status. On the other hand, physical exercise is sacralized as an expiatory ritual of the sedentary way of life that motorization and automation of daily life imposes on us.