Force of a vehicle Physics

These meme looks at the risks imposed on other road users by different types of movement, including walking, cycling and driving a heavy SUV (or Chelsea Tractor as they are more accurately known).

Working:

USER  MASS (KG)  SPEED (MPH)  KMH   M/S   1/2MV2   BRICKS 
PEDESTRIAN                80 4             6         2                      126                      1
CYCLIST              100 12           19         5                   1,422                    14
SUV           2,250 45           72       20              450,000              4,500

This is based on:

  • A pedestrian walking briskly at 4mph, weighing 80kg with any bags.
  • A cyclist at 12mph (typical urban speed), weighing 100kg with bike and equipment / bags.
  • A heavy SUV (eg Toyota Highlander Hybrid), weighing 2,000kg + 250kg for occupants and luggage.

Speeds are based on typical urban speeds on an arterial road, which might have a speed limit of 40 mph (UK typical), and where drivers will be typically exceeding that by around 5 mph.

A Lego 2×1 standard brick weighs just lessthan 1g (14 weigh 10g). The brick in the photo weighs 4.5kg. The comparisons are based on weight rather than volume. A comparison based on volume (ie using actual Lego bricks to make a “real” brick) would result in a much larger “brick” for the SUV.

 

The shocking truth about empty cycle lanes that cyclists don’t want you to learn

This is a holding place for a blog post which will follow shortly.

This will be a blog post about how “empty” cycle lanes are indeed empty most of the time – exactly as they are designed to be!

Many cycling advocates will talk about the numbers of people who can be moved through a cycle lane, but this is often based on the very highest levels of usage in Denmark or the Netherlands.

Most cycle paths will actually have relatively low usage, when compared to the absolute maximum they could hold. This is quite different to road lanes which are usually at saturation point in terms of the vehicles they are carrying, whilst it is the norm for metro systems to run trains which are full at peak times.

So why might some people want to avoid sharing these figures, and are cycle lanes still beneficial regardless?

Transport space usage compared

Traditionally, a lot of transport planning as focused on the movement of vehicles through road space, whereas contemporary thinking is moving towards looking at the number of people which can actually be moved through any given space. In the wider sense, movement space must also include space for active travel (walking and cycling) as well as for rail tracks or other high quality mass transit provision.

As far as the Plastic Planners are concerned, the idea of this setup is to show in very simple terms how many Lego people we might be able to move through any particular corridor.

There are various comparison of travel space which have been done using photo set ups (especially to show the space needed to move a certain number of people), and these comparisons often quote movement in terms of thousands of people per hour through any given point.

Rather than quote in such large numbers, I wanted to scale this down to the very basic starting point of moving one Lego minifigure (person), and then show how more efficient modes can move more people through the same space.

Which modes are considered?

At the most basic level, any comparison of space usage and transport will start by looking at three major types of movement – active travel (mainly walking and cycling), public transport or transit (from shared taxis up to high-speed trains, but in this case just a bus lane and a metro) and private motorised transport (cars and taxis).

For this set up, the focus is on an urban area, so train really means a subway or metro. For longer distance services, the figures will change a little, as they will for the road usage.

In order to make this comparison workable, it’s best to stick to land-based transport, because ports and airports would show a very high intensity of usage, whereas the actual routes taken by ferries and aircraft would have a much lower distribution, even if they were not actually using dry land at the time.

These comparisons are also just looking at the movement of people, so any consideration of movement in a “general” traffic lane would need to ignore vans, trucks and any other kind of commercial, service or utility vehicle.

Within each mode, there is also some considerable scope for variation in terms of how much space each vehicle might take up, how many people can be carried within it, and then perhaps most crucially how much space is taken up by the gaps between the vehicles?

If there is one factor which is much less relevant, then it’s the typical speed of each vehicle. This is largely a comparison about moving people within urban areas, since it also includes walking and cycling. In order to compare longer distance journeys, walking and cycling would have much less relevance, and then for longer intercity trips, there would also need to be some kind a comparison with flying, and then perhaps even more focus on different types of train.

So within this urban setting, different types of cars do take up differing amounts of road space, but there’s much less variation in the gaps between cars. Also, if the average occupancy of each car is just 1.5 (that’s a UK figure), then it doesn’t really matter that much a car has 4, 6 or even 7 seats, since most of these are going to remain empty.

Mass transit is also far from 100% space efficient, since most railway lines operate well below the theoretical maximum capacity that the tracks could bear, many trains are just 2 or 3 carriages, and although commuters will always complain about them, no train line actually operates at 100% of capacity 100% of the route 100% of the time (and nor should it, for obvious reasons).

In order to come up with a comparison that is useful, I would need to look at the possible scenarios which are being compared.

The starting point is the well circulated graph, which actually dates back to 1991. However, there is no reason to think that any of the fundamentals of changed since then – average car occupancy rates are largely the same, and the way people would walkoff cycle through space remains the same. Whereas there is been a phenomenal amount of Metro building since this date, the actual maximum capacity per line has only changed slightly, based on improvements to signalling and some systems running slightly longer trains. However, if there is one major change, it is the emergence of bus rapid transit, particularly in South American cities.

In order to justify this comparison, I think there are 3 key figures which could be looked at:

  • Theoretical maximum capacity – the number of people who could be moved through a space if every mode was used in the most efficient possible manner.
  • Actual maximum capacity – the busiest known corridor for each mode.
  • Typical usage – a comparison figure which is actually relevant to urban areas today.

Theoretical maximum capacity

The most intensively used Metro line in the world is line 14 in Paris, which has a train every 90 seconds, or 35 trains per hour. It is unrealistic to expect any major improvements on this figure, due to the limitations of signalling and the ability of trains to stop in an emergency, and also due to the amount of time taken for passengers to get on and off at each station.

In theory, Metro stations could be built with separate platforms for boarding and alighting, as is the case in a small number of locations. However, this will be problematic at interchange stations where passengers might want to change from one train onto another one behind it that uses the same tracks, but is going to a different destination (on a Metro line which has branches). However, based on the potential for a small time-saving with this arrangement, it is suggested that a Metroline could be built at some point in the future which could handle one train every minute.

Which modes to consider?

  • Taxi
  • Car
  • Bike
  • Bus
  • Walking
  • Train (metro)

what isn’t considered?

This comparison makes no account of the speed of travel, simply the ability to move people through a fixed point.

It’s also been limited to a selection of comparisons which can be rounded to a simple number of Lego people, and I’ve then rounded it further because it was a very close fit to a pattern of doubling. This means that it doesn’t include every single variation of bus provision, nor can it include a comparison between different train types.

For the same reason, motorbikes and scooters are not included in this comparison.

“But I can drive faster than I can walk”

This is a question for another comparison. If traffic is moving like treacle, then you won’t just be moving slower than you can walk, but you’ll also be making walking and driving difficult for everyone else, because you will be taking up the most road space. Of course, most traffic does move a little bit faster than treacle, even in a plastic fantasy land. But the starting point of this comparison is simply about how to move large numbers of people through a narrow amount of space. Ultimately, whether it’s a large crowd of pedestrians or a fast commuter train, the people still have to pass through the imaginary line that is measuring these counts!

This article only considers movement of people, not freight.

Train (metro)

The longest subway trains currently in service are on the New York subway line X, and these have 11 coaches. On some subway systems, the coaches are slightly shorter than might be used on a mainline railway – this means that the tunnels can have sharper curves. Some European high-speed services are formed by joining to 8 coach sets together, whereas locomotive hauled passenger trains could have a rake of 20 coaches or more.

Capacity is increased further by using double deck trains, and these are common on many North American commuter services, as they are on the regional networks in the countries such as Switzerland, the Netherlands and France. However, double deck trains are undesirable on a subway network because they would significantly increase the dimensions of the tunnels. Even on a rapid transit network that was largely on the surface, or even on elevated tracks, double deck trains would still have limitations in terms of how quickly passengers could get on and off the platforms from the upper decks. Because of the space taken up by the stairs, double deck certainly doesn’t mean double capacity; on the French TGV, it’s more like an increase of 45% over a single deck service. In terms of theoretical maximum capacity, the potential for double deck trains is not included.

In theory, subway trains could be just as long as any other type of train, assuming that they are being considered for a new line, rather than for an existing route where platforms might not be long enough (this is a common problem on many parts of the London Underground). However, very long tube trains would be undesirable, for the simple reason that many journeys on subway systems might only be for a few stops, so having platforms which were 400 m long (as would be needed to take a double TGV), could mean that in some cases the platforms were almost as long as the distance to the next station! For the sake of this comparison, a maximum theoretical train length of 12 carriages is used.

The maximum loading capacity for a railway carriage would theoretically be reached by quite literally turning it into a cattle truck and having no seats at all. On mainline trains, facilities such as toilets would also be removed, and the assumption would be that there would be no buffets or any other kind of catering. However, building trains in this way would be completely undesirable, and even if many people do stand for much of their journeys, there must always be some seating as a basic accessibility requirement.

Capacity could be optimised by only using flip seats, but if this was the case, then the assumption would be that passengers who were already seated would then stand for the busiest part of the journey so that other people could get on – this in reality is unlikely.

The maximum typical capacity of a subway type train is therefore reached when a small number of seats are provided, often simply with rows of seats on each side and then a large standing area in between – this is the standard configuration on London overground type trains and more recent “subsurface” stock.

Some capacity improvements can also be brought in by using wide gangways between carriages. On the London Underground, where older stock has no connection between carriages, opening up the train in this way can increase capacity by around 20%, whilst also making it easier for passengers to move around and find seats as and when they become available.

Walking

These figures are based Oxford Street in London, as provided by TfL (Transport for London). Their claim is that Oxford Street is the “busiest pedestrian street in the world”.

Given that there is an intense political furore unfolding right now about the future of this street, and plans to remove all motor traffic from it, including buses, this is a good enough place to start. Oxford Street will also have two stations on the new east-west Elizabeth line (a regional metro similar to the RER in Paris), which opens later this year.

Bus/tram

We know that a conventional single decker bus, as used in most places throughout the world, can carry around 60 people if everyone has a seat. Take out some seats so that more passengers can be squeezed in at peak times, and the maximum capacity of a single decker bus goes up to about 80 people. This will include space for wheelchair users and prams, as well as for some luggage.

In the UK, and in a small number of other locations, such as in Hong Kong and in some German cities, double-decker buses are used to increase capacity. However, as with the example of double-decker trains above, a lot of space ends up being taken up by the stairs, and these can also cause a significant delay in loading and unloading passengers.

The most effective way to maximise the capacity of a bus is to use an articulated or “bendy” bus. These buses can have multiple articulated sections, especially if they are running on their own dedicated right-of-way, where there aren’t any concerns about conflict with other road users, and in particular with cyclists. In terms of capacity, there is little difference between an articulated bus and a tram, so for the purposes of this exercise, they are both treated together.

The most heavily used busways in the world are both in tunnels – the Lincoln Tunnel and Hong Kong harbour tunnel respectively. There are 2 fundamental reasons why these busways are used so intensively – firstly, since nobody wants to get off a bus in the middle of a tunnel, there are no delays due to stopping, and also, because the number of river or harbour crossings is inherently limited, traffic from a wide area can be funnelled through these locations.

Both of these busways have real life usage in excess of 600 buses per hour, or one bus every 10 seconds. Based on the length of the bus and on stopping distances, it’s unlikely that capacity in either of these locations could be significantly increased, because even with “platooning” (see the car capacity section), they would still need to be sufficient separation between the buses in case any bus in the “chain” needed to stop suddenly. Also, at this level of capacity, the length of the bus more of an issue than the separation – check that.

However, a bus rapid transit system needs to allow buses to stop to load and unload passengers. Unlike a subway system, a bus rapid transit system can quite easily incorporate the facility for buses to overtake each other, either because some buses might spend less time at the stops, or simply because an express service could move past the slower services at some of the stops. In the very highest capacity systems, such as the trans-Millenio system in Bogotá, the busways actually operate with 2 lanes in each direction, so the faster buses can move past the slower buses at any time. However, adding a 2nd such Lane also means that a significantly larger amount of road space is needed for the system, and the comparison here is between one lane of usage, so for the purposes of this post, it will be assumed that the lanes themselves are single carriageway, but that it is possible for buses to pass each other in the stations. This space isn’t included in the calculations, nor is any platform space included for the calculations about trains. This is largely just in the interests of simplicity – a surface railway line would also have embankments and cuttings, whereas any underground railway technically takes up no space at all, other than access to the stations. However, roads also take up space in many different ways, including space on pavements taken up by signage gantries, barriers and then also slip roads, and a full assessment of road space should also consider how much space is needed for parking at each end of the journey – however, this is kept out for the sake of simplicity.

It might be reasonable to suggest that a triple articulated bus, which can hold up to 250 passengers could run up to once every 15 seconds, allowing time for access and egress at the stations, and also assuming that the busway operates with minimal delays at signals., If they are used at all. This isn’t entirely unrealistic – many South American systems do operate with total grade separation, typically in the middle of a major highway.

As with subway systems, rapid transit buses can be configured with a relatively no a relatively low number of seats, and at peak times, it’s entirely reasonable to assume that every bus will run full or almost full.

One bus every 15 seconds would constitute for buses per minute or 240 per hour.

240 buses per hour with a capacity of 250 passengers would represent 60,000 passengers per hour.

Cycle Lane

We know that there are cycle counters in Copenhagen which regularly count as many as 35,000 cyclists per day at the busiest times, typically late in the summer as university students return.

However, there is still more of a seasonal aspect to cycling down there is to other modes of transport. This is often wrongly attributed to the weather, which is a factor, but which doesn’t actually stop people cycling – in cities which provide decent facilities, cycling is always year-round, even in the frozen winter, because the cities will keep their cycle path networks free of snow. A far more significant factor in determining cycle Lane usage is the University terms time, because students are more likely to cycle than any other sector of the population.

However, even though Dutch cities don’t tend to broadcast cycle counts, there are a number of places where usage is measured, and there are cycle paths in cities like Groningen or Utrecht, where in excess of 20,000 cyclists per day per direction are measured throughout the year. So how about on an hourly basis? Typically, peaktime traffic might account for around 50% of journeys on a trunk route in and out of the city centre, and if the peak period occurs over 2 hours, then the busiest hours might each account for around 20% of the total, assuming that most of the peaktime loaded is in one particular direction.

This would give us and actual usage of a cycle lane of around 4000 people per hour. However, a cycle lane does not have to be as wide as a general traffic lane in order to be effective. In particular, a cycle lane which is configured for bidirectional usage could have cyclists riding 2 or 3 abreast in one direction, whilst still also allowing people to ride single file in the other direction.

Maximum capacity

It is a common complaint of critics that the newly installed cycle paths in London, especially the new cycle path which runs east to west across the city is so often “empty”. Yet the figures also show that this cycle path carries more people than all of the 3 general traffic lanes which run alongside it. So why is this? Yes, London traffic has been moving like treacle for the last century, and yes, the general traffic lanes are heavily constrained by the limited capacity of the junctions, but don’t cyclists also need to pass through the same junctions? This is why the cycle path do indeed so often look empty – cyclists can pass through junctions very quickly, because they don’t have to leave large gaps between each other, and also because it’s very easy for cyclist a bunch together through junctions.

This means that even the busiest Dutch cycle paths will often look empty, because even at 4 or 6 or 9000 people per hour, a cycle path is still well below its maximum theoretical capacity.

To work this out, we have to look at the sort of volumes of people who can use a cycle path when there is a special event on, and then to consider how many people could use a cycle path if everyone was bunched together with only a minimal gap between each cyclist:

Consider:

  • A standard bicycle is around 1.2 m long.
  • At a typical urban speed, bicycles can move very close to each other, and in some places, the wheels can almost overlap.
  • Let’s allow 2 m per bike.
  • The comparison for this purpose is to consider the maximum capacity per lane per hour, and for all of the other modes, this is a driving lane 3 m wide or equivalent.
  • A 3 m wide bicycle lane would comfortably accommodate cyclists riding 3 abreast in the same direction (the bidirectional option the bidirectional factor is not considered in this theoretical maximum).
  • It is reasonable to assume that this cycle lane might have a “continuous green” signalling priority – this is used successfully in Copenhagen.
  • To make a fair comparison in an urban setting, it would have to be assume that sooner or later, even with a continuous green, the cycle lane would need a junction with another cycle lane, and that at some point, priority would have to be yielded at a major intersection. However, if the question is about theoretical maximum capacity, then these junctions could also be separated, as is the case in some Dutch towns (e.g. Harlton).
  • At an average speed of 20 km/h, each bicycle would be moving 0.3333 km/m or.
  • At an average speed of 18 km/h, each bicycle would be moving at 0.3 km/m or 5 m/s.
  • If each bicycle required 2 m of road length, then 2.5 bicycles per second per row would pass the given point.
  • Since there would be 3 rows of bicycles, then 7.5 bicycles per 2nd would pass the given point.
  • This would work out as about 500 per minute.
  • This would work out as 30,000 per hour.

Driving

This comparison is based on the maximum capacity of a general traffic road, from figures researched by Transport for London.

Since this article is about moving people, the assumption is that all traffic will be made up of passenger cars, with 1.5 people per car.

Taxi

Taxis, especially those which are hailed on demand (known as black cabs or Hackney carriages in the UK) are the least efficient form of transport when it comes to road space used for movement. This is because, like private cars, they are mostly used to move one person at a time, but also because they spend a huge amount of their time cruising around empty, looking for business. This means that the overall occupancy for taxis in London is just 0.8 passengers. As with public transport, we’re not counting the driver!

However, just because taxis are inefficient in their own right, they still have an important role to play in an integrated transport system, because a short taxi journey to the station can enable a longer one by train. Also, although they can take up space on a rank, taxis don’t spend all day parked like so many private cars used for commuting do. However, parking space is a topic for another post.

Points for debate

At the end of the day, this is just a meme about moving people through space. Another one will follow about “movement per lane”, which will also consider the realistic travel speeds, hence total people x kilometres moved per lane per hour.

But ultimately, moving people is one part of the equation. How much energy is needed to move each person, and what impact that has on the local air quality is another.

Then there is also the question of the quality of the street itself. If one method of moving people is very space efficient, but it’s a little slow, is that such a bad thing if it still gets the job done? Is it better to move people through a busy shopping street in a constant stream of standard buses, or is it better to move them together in an articulated bus or tram? Of course, it’s better still to move them under or over the street in question, and that is also a matter for another comparison, because grade separation (running a stream of traffic under or over the street) might have huge advantages for the street itself, but it’s also hugely expensive compared to running along the surface.