Diversity rather than monoculture is the key to improve the health of urban mobility systems

A recent visit to Lisbon provided an opportunity to see perhaps the world’s largest living lab for micro-mobility. The term micro-mobility has entered the transport vocabulary thanks to the emergence of new app based shared use modes such as dockless electric scooters (like those pioneered by Lime and Bird but also by local entrepreneurs), electric bicycles and mopeds. Those new entrants look likely to become established features of urban mobility systems alongside car share and bike share. Lisbon’s city government has largely embraced this mobility revolution, driven by a desire to provide a comprehensive ecosystem of modes to reduce dependence on the car for urban mobility. In contrast to what we saw when share bikes were introduced here, the operators were taking greater care of the fleet. While many had fallen over round the city after a windy day, an early morning inspection the next morning found that staff had been out and stood the scooters up and locked the Jump e-bikes to bike parking infrastructure.

Sperling and Gordon’s book titled ‘Two billion cars: Driving towards sustainability’, highlights  the inherent weakness of urban mobility systems built round the monoculture of the private car. Over the course of my career I have seen the priority of the transport profession, or at least the forward thinking members of the profession, change from moving cars to moving people. The addition to the new micro-mobility options presents challenges and opportunities. The views of transport planners I met in Lisbon aligned with a view I heard expressed in a workshop I was involved in running at this year’s TRB annual meeting - these new modes will add to the pressure on cities to make greater provision for safe use of what I reluctantly refer to collectively as ‘vulnerable road users’. I personally dislike that term because given the number of people who tragically die or are seriously injured in car crashes round the world it is clear that the a more appropriate use of the term vulnerable road users would encompass people in cars as well.

We are yet to see independent confirmation of the nature of the mode shift these new micro-mobility modes will produce but it is clearly not all out of cars. There are safety and mobility challenges to be addressed and in part that will require updating of current reporting of crashes and hospital admissions to ensure these new modes are captured accurately. However there was no sense that the sky has fallen in from the experience so far in Lisbon. The streets were not littered with the bodies of the dead and injured.

The operations of large fleets of GPS equipped vehicles provides a rich data base for understanding patterns of use of these new mobility options. There is no doubt that the disrupters are having an impact and not just in terms of the use of their vehicles. Data collected by the City Council in Lisbon had flagged the existence of a potential  ‘halo effect’ (I think that term might be copyright to Adrian Webb from the Victorian DOT) whereby the normalisation of scooter use in the city has seen growth in ridership of privately owned scooters in addition to the shared variety.

The National Transport Commission is reviewing the regulations for innovative vehicles and released a discussion paper earlier this year (NTC, 2019). The following content draws on a submission I made to the NTC.

Our regulatory system is currently framed in terms of four fundamental forms of road system users: pedestrians (which also includes users of personal mobility aids like wheelchairs and mobility scooters), bicycles (which has been stretched to cover electric power assisted bikes, and now is being ‘creatively’ interpreted to provide guidance on where electric scooters can be used), Mopeds/motor cycles and motor vehicles. The system needs to have the flexibility to deal with innovation. At present it doesn’t. While this only part of the solution, I believe we need to reconsider referring to bicycles and instead follow the lead of countries like Singapore and introduce a new collective term of ‘Personal Mobility Devices’ to refer to both current (bicycles) and emerging options (e.g. electric scooters). Kinetic energy management would be an appropriate concept to govern what can be used where and how. Radial I know, but the health of our urban transport systems depends on diversity and our regulatory systems need to be framed in a way that does not enshrine existing monoculture but provides a sound framework for assessing new opportunities. We moved away for horse drawn carriage and horseless carriage as a distinction years ago, I think it is high time our regulatory system takes another step in its evolutionary pathway.

Beyond Roads to Mobility

For many people, the road network is an extension of the proverbial sand pit at kindergarten where the need to ‘share’ is paramount. With our cities getting bigger and more dense, there is going to be a greater need to ‘share’ the existing, limited network. In more recent years the transport profession has embraced the concept of ‘road space management’, in recognition of a strengthening priority for moving people not cars. However road space management is currently framed in terms of ‘sharing’ the space from kerb to kerb rather than from property line to property line.

There is potential to think more broadly about ‘mobility space management’ in the zone from property line to property line on either side of the road. The concept of movement and place, which is becoming embedded in contemporary road network management, would then be relevant. A critical issue is the zone between the property line and the kerb . While in large parts of our urbanised areas that space caters for very, very few people, in others it provides scope for footpath dining and access to adjacent commercial and public land uses that make an invaluable contribution to urban life.

Some jurisdictions allow people to ride bicycles on footpaths, one example of extending the concept of sharing space beyond the kerb and treating that zone for movement. In other jurisdictions footpath cycling is prohibited or strictly limited. This reflects differences in the priority of movement versus safety with specific concern about whether safety will be maintained in a shared use environment with due respect given to the needs of other when riders are operating in that space. However that space is already shared by persons in motorized mobility devices and electric wheelchairs highlighting that motorized devices of some form legally operate in a space which some seek to retain as the exclusive domain of pedestrians. Clearly these are precedents for greater sharing of a more broadly interpreted movement space which deserve careful consideration.

There is potential to draw on the concept of movement and place and extend it to the space between the property line and the kerb.  As part of that reframing, kinetic energy management is a key consideration.

New vehicles and the relevance of kinetic energy in the context of a ‘safe system’

Our regulatory frameworks struggle to cope with vehicle innovation, particularly in relation to light weight personal mobility devices. In that context, kinetic energy management is critical consideration particularly when assessing the potential for injury in the event of a crash (Corben et al, 2004; 2010).  Kinetic energy is calculated as mass times velocity (speed) squared. Regular bicycles and racing bikes can generate similar orders of magnitude of kinetic energy as the former is heavier and slower and the latter is faster but lighter.

Contemporary road safety policy is being driven by a ‘Safe systems’ approach, based on the principle that our life and health should not be compromised by our need to travel and that no level of death or serious injury is acceptable in our road transport network. Safety and risk need to considered in this context.  The acceptance of risk is an integral part of human existence. We take risks as a result of the food we eat, the air we breathe and the activities we do, or do not, engage in. Humans do not act to eliminate all risks in their lives. Risk management rather than risk minimisation is central. A Safe System approach does not imply all risk is eliminated but rather rigorously managed.

When considering kinetic energy management in the context of a safe system, a critical issue is the amount of kinetic energy transferred to a human body at the time of a crash Kinetic energy is traditionally managed by limiting speed, careful design of the road side environment, vehicle bodies deforming to dissipate energy and personal protective equipment built into the vehicle such as seat belts and air bags.

Referring back to the kinetic energy model, we can eliminate the risk of death or serious injury by eliminating kinetic energy in an incident. That can be achieved by limiting speed to zero – that is prohibiting movement. That risk elimination approach would then deny the community of the benefits associated with travel and activities undertaken in different places. Clearly a more nuanced approach is required.

Regulatory framework   

A fundamental weakness of our current regulatory approach is the prescriptive nature of many standards which make specific reference to a particular type of vehicle. This means that in our current system, a new device must be classified as either a pedestrian, bicycle, motorcycle or a motor vehicle. New types of personal mobility device then need to be shoehorned into one of those categories. Perhaps the clearest example of the challenge of that mindset was the emergence some years ago of the Segway Personal Transporter. It was neither a pair of shoes nor a bicycle and the regulatory framework struggled to work out what to do with it. In retrospect it is a wonder that we don’t have a regulatory system based on pedestrians, horses and motor vehicles with mental gymnastics required to creatively classify ‘bicycles’ as ‘horses’ under the regulations. Frankly our current regulatory framework is not far removed from that when we contemplate classifying electric scooters as bicycles to determine where and how they can be used.

Key elements of a more robust framework for regulation could involve:

  • Distinguishing Personal Mobility Aids (required for persons who have a disability which impacts their movement) from Personal Mobility Devices (used by persons who do not have a disability) with the maximum speed under power assistance defined for those two vehicle types on the basis of kinetic energy management. Individuals using Personal Mobility Aids could be given access to areas of the movement system, for example between the property line and the kerb, not available to Personal Mobility Devices, but under kinetic energy limits which reflect the place function of that location.
  • Framing access to the space from property line to property line, under a mobility space management paradigm, with a distinction drawn between Low, Medium and High Kinetic Energy Zones and their suitability for Mobility Aids or Mobility Devices.  In this way Mobility Devices could banned in some locations due to the ‘place’ value of the space from property line to kerb. Signage could be one way of communicating that to users in areas where Mobility Devices were not permitted.
  • Thinking beyond the ‘vehicle’ itself to defining personal protective equipment (e.g. helmet requirements) as well as rider licensing/permit requirements dependent on the potential kinetic energy and the ‘zone’ where it operates.

To wrap up

The challenges facing our urban areas require fresh thinking because the existing paradigm is not delivering the outcomes expected or needed by the community. The concepts and ideas presented here need further development but are based on sound principles which would provide a defensible basis for the evolution of policy. Managing this socio-technical transition with clearer consideration of management of both kinetic energy and mobility space requires further evidence to inform policy development.  Pilot or demonstration projects, which are rigorously evaluated, would have a valuable role to play and need to be embraced as a priority in order to develop measured policy response to these emerging innovative types of vehicles.

Professor Geoff Rose

28 March 2019


Corben, B., Cameron, M., Senserrick, T. and Rechnitzer, G., 2004. Development of the Visionary Research Model - application to the car /pedestrian conflict, Monash University Accident Research Centre, Report No. 229.

Corben, B., van Nes, N., Candappa, N., Logan, D.B., Archer, J., 2010. ‘Intersection study – Task 3 report’. Monash University Accident Research Centre. Report No. 316c. (PDF, 2 MB)

National Transport Commission (2019) Barriers to the safe use of innovative vehicles and motorised mobility devices. 45 pp.

Sperling, D. & Gordon, D. 2009. Two billion cars: Driving towards sustainability, New York, Oxford University Press Inc.

The Economist. 2018. The Global Liveability Index 2018. The Economist Intelligence Unit Limited.

Contact: Professor Geoff Rose

Phone: +61 3 9905 4959

Email: geoff.rose@monash.edu