The hierarchy of sustainable travel

Part of transport policy in the UK is the sustainable transport hierarchy. There are lots of versions of this, as it turns out - see for example here and here.

But generally put, the hierarchy has a number of tiers:

• Walking and wheeling
• Cycling
• Public transport
• Taxis and shared vehicles
• Private cars
• Air travel

Generally, modes are more sustainable as you go up the list - lower pollution, lower carbon emissions. The more active travel modes at the top of the list are also much healthier. They're also more efficient as you go up the list - cars in particular are incredibly inefficient users of the precious space in urban environments. And the costs of providing the infrastructure vary quite widely - there are massive external costs associated with motor transport, which are much higher than the direct income from taxation.

With that, policy should prioritise modes further up the hierarchy. You do see a fair amount of talk about this, although action is far less obvious.

One recent change to the Highway Code, for example, prioritises pedestrians and cylists over vehicles turning into side roads.

But generally, the reality is that the default is to prioritise the car, sometimes subtly. Consider Cambridge Railway station. Come by car or taxi, and you arrive close to the front door. Cyclists are a bit further away, and have to navigate steps. Bus users are down the end of the street. Pedestrians have all sorts of obstacles to navigate.

There are lots of other examples. Pedestrian crossings - if they exist at all - are routinely placed and timed for the convenience of motorists. Bus and cycle lanes are configured and only exist where it's convenient for motorists.

To improve matters, one might consider a range of interventions. These have to be done with care - simply concentrating on one level in the hierarchy runs the risk of causing harm at other levels. Although, generally, an intervention at a specific level is more likely to benefit the tiers below it, while running the risk of harming levels above it.

One example here is that ways to encourage cycling can harm pedestrian activity - shared paths are obviously bad, but taking pavement space for cycle parking also make the lives of pedestrians much worse.

One extreme consequence of the above is that if you want to improve the lot of motorists, you should work to improve the tiers above - as people shift to walking, cycling, or using public transport then you reduce congestion, and that's really the best way to benefit motorists.

Conversely, designing for cars makes the levels above less attractive, which pushes more people towards car use, increasing congestion and making life for motorists worse.

Properly connected bus services?

Dirk Gently was a great fan of the fundamental interconnectedness of all things. Those who are responsible for our public transport? Not so much.

At least where I am and for the journeys I tend to make, joined-up thinking really hasn't permeated into public transport.

It wasn't that much better in the past - consider how many railway stations are set distant from their notional destination. Blame the Victorian NIMBYs for that one.

Bus stops and bus stations tend to be at fairly random locations. At Cambridge Railway station, they're relegated to way down the road. In Cambridge, some go from a random point on the street on Parkside.

Here in Cambridge we have a number of bus services that are operated in some sort of isolation. There's the regular (Citi) buses; the park and ride services; the U; the guided busway; and recently the intriguing Tiger bus routes. There are several different companies involved.

Cross-ticketing really isn't a thing. If your route involves multiple suppliers, pay them separately. If the convoluted route map involves multiple routes, pay extra.

The new T4 and T5 are allegedly timed to interchange, so that you can swap from one to the other depending on your destination. That's good, but that it gets specially called out indicates that it's a rarity. There's even a Hopper ticket, but again that's part of the problem - you should be able to swap buses to complete your route without penalty.

I was at a event last night and asked about a transport survey that had been done. Had they asked where people needed to get to? Nope. Not at all. This sort of basic information is critical to working out what sort of transport provision is required - where to put the cycle ways, where the bus routes run - but we don't have it, it seems the powers that be aren't trying to get it, and we end up with public transport being provided completely at random. And they they wonder why people are unhappy and patronage is low.

Maybe a move to bus franchising will improve matters, as that does give uniformity of control and decisions about route planning. It's difficult to see how it can get any worse.

Cheap single bus tickets considered harmful

Here in the UK, the government placed a £2 cap on single bus fares. Cheaper bus fares is a good thing, surely?

The snag with this limit is that, at least in Cambridge, it makes 2 single tickets cheaper than a return (OK, there isn't a return, there's a day ticket). It's even cheaper that the advance flexi ticket (which is the day ticket on the smartphone app).

(One possibility is that the single prices have distorted the ticket pricing structure, and that Stagecoach have had to increase the prices of the other tickets - the ones that you would expect to be discounted - in order to avoid making a loss.)

What this means is that instead of buying a day ticket, or using the app, people - including myself - buy a separate single for every journey.

The time it takes for everyone to buy a ticket on the bus is significant - yesterday I timed it and it was typically 10s per passenger. You have to let the driver know your destination and what ticket you want, the ticket machine needs to be set for that, you have to tap your smartcard, the machine has to register it, and the ticket has to be printed and collected. That's when it works, as occasionally the ticket machine doesn't read the card first time (it seems even less reliable with payments by phone, perhaps the technology hasn't quite matured enough).

Some time ago I wrote about The effect of passenger boarding on bus services. For the last couple of years, largely due to the extensive use of the app which meant that people just marched onto the bus at full speed waving their phone at the driver, the fraction of time a bus sits waiting for passengers to board had actually declined sharply. The effect of the lower single fares is that now the time spent waiting for passengers to board is even worse than it was when I looked at it 5 to 6 years ago.

Yesterday, with a full bus at peak afternoon times, the impact on my supposedly 30 minute journey into time was an extra 10 minutes at least. There basically isn't any slop in the timetable, so add this to the roads being congested with too many cars and it's hardly surprising that buses become ridiculously late during rush hour.

Another example of unintended consequences.

Smart Meters and electricity use at Tribble Towers

We first got moved over to a smart meter some years ago. It partially worked great for about a day, then stopped.

The whole thing has been a bit of a shambles. It wouldn't take electricity readings, the in-home display (IHD) wouldn't communicate with the meter, our meter wasn't even registered with the supplier, and that sort of thing.

Even now, despite having a smart meter that's capable of reporting usage accurately and frequently, our supplier makes up bills that have at best only a passing familiarity with our actual usage.

Having a smart meter can, in principle, drive savings in two ways.

First, it allows very granular billing. British Gas have a half price tariff between 11 and 4 on Sundays. This sort of variable billing simply isn't possible without a smart meter. Fine, so we do most of our washing in that window, run the dishwasher, cook Sunday dinner, wait until just after 11am for our morning coffee and make sure we boil the kettle for tea in the afternoon just before 4pm.

At one stage they had a variety of short-notice periods of cheap electricity too.

I'm guessing the advantage of this to the suppliers is that they can do a bit of demand management, shifting load from peak times to idle times, although I think it'll have to be rather more dynamic to really do any good. And if we save a bit of money in the process we're not going to complain.

The second saving is if the consumer can use the smart meter to track usage in real time and identify what's actually using all their electricity. That's proved to be a bit trickier.

After far more work that I expected, I now have a much better handle on where all the electricity in Tribble Towers is going. The smart meter itself wasn't much help in providing answers, although it did provoke a lot of questions (I think I've turned *everything* off that I can, why are we still using 200W?) - so having the smart meter was a benefit.

In our house, the heaviest usage comes from the kitchen. That's where the oven, grill, hob, microwave, toaster, and kettle are. They aren't on for that many hours a day, but when they are their usage is huge. There's also the fridge freezer - we've recently replaced ours (because the old one failed over the summer) with something that's actually pretty energy efficient, but it's obviously on 24 hours a day, every day.

The next biggest room is the living room. All that electronics - the TV and friends. What I did learn was that the Sky boxes are incredibly power hungry, and they don't vary that much between on and standby (25W, all year long). So much so that we pulled the plug on the Sky box and TV in the guest room because nobody has watched anything on it for years.

The broadband router is another big contributor. Again, it's power usage is modest, but it's on all the time (and necessarily so).

Another thing I learnt is that lighting pulls a lot of power. We have a mix of lighting types, some very efficient low energy bulbs, a number of specialist bulbs we can't get low energy versions of, and some pretty inefficient bulbs. In particular, the uplighters in the living room pull 80-100W each. Unfortunately they're already a low-energy variant (low here being a relative term). They give very good quality light, and we're not going to sit in the dark. But what we now do is leave a very low energy side light on if we're out, rather than the main light.

I was a little surprised that my office and all the computers in it wasn't consuming all that much power, in relation to some of the items mentioned above. My main monitor draws more power than the computer it's connected to. And while my array of servers pull a lot of power when on, they're not on all that many hours. My entire array of systems and network, which is basically what I use all day, is maybe 15% of our total household usage.

And there's the long tail of things in standby, chargers, and the like. Each consumes very little power, but there can be so many of them, and they tend to on all the time, so that adds quite a bit.

We have managed to identify a few inefficiencies and waste, and have reduced our electricity consumption overall by maybe 10% over the last year or so (we had already largely transitioned to low energy light bulbs, which would have been maybe another 10%). That seems to me to be the sorts of savings one might expect; anything much larger requires more radical change, especially in how we cook.

Can we avoid lockdown?

I considered briefly the magnitude of the response needed to address the COVID-19 pandemic, and concluded that - roughly - a factor of 10 reduction in social activity was required.

The question then becomes - how to achieve that?

Clearly, lockdown works (although the fact that our decline was slower than it should have been indicates that it wasn't working optimally - lacklustre leadership, being two weeks late into lockdown, and a significant selfish minority who clearly thought the restrictions weren't for them, contributed in part.

There are massive negative economic and societal consequences of lockdown, so it would be better to avoid it if you can. Can we?

What are the options?

• Working from home: this dramatically eliminates both the work contact and public transport contact elements. It's a sufficiently large component that if you don't do it, you can't win. So, where possible, people should work from home. There's still going to be a set of people for whom this isn't possible.
• Avoid public transport: yes, this helps a bit, but has negative impacts. Remember, we have a climate disaster looming on the horizon. If the majority work from home, then that reduces the occupancy - and thus the risk - for those that need to travel.
• Eliminate large-scale events: the sheer number of people, and their closeness, surely indicates that live theatre, sport, concerts, and the like, simply can't be contemplated for a while.
• Rethink large-scale events: large scale events have a couple of problems, first you're putting a huge number of people in direct contact at the event, and you're having a lot of mixing on the way in and out (and many will visit other social venues as part of the event, making things even worse). But if you only had isolated boxes - and many venues already have some provision like this, after all - with no way for people in different boxes to mix, then you can get to a point where it's not really any worse then the groups meeting to watch the event on TV in a bar or at home.
  
• Shut down bars and restaurants: there's a massive economic and social hit from this. This is a smaller version of the question about avoiding total lockdown.
  
• Rethink bars and restaurants: how far can you eliminate the risk by having isolated groups (bubbles), table service only, one way routes, and ramping up the restrictions? I think you can actually go a long way from the norm. Having visited a few bars and restaurants, most are doing a pretty good job. The fundamental problem again is those in the selfish subclass who won't obey the restrictions and ruin things for everyone. You're going to have massively reduced occupancy (simply by spacing people out) which reduces the risk. Which also reduces the risk because the reduction in capacity means people won't be able to go out as often.
• Testing: if you test everyone continuously, and just barricade the infected, then you should allow everyone else to get back to normal, right? Not so fast. The point here is that a single negative test doesn't mean anything. Worse, any contact means you need to get retested - over and over. That's the sort of thing you have to do in hospitals, it's simply not feasible to cover the whole population at the required density.
• Early closing: I've seen the suggestion that bars should close early. I'm not at all sure that this will help much, as it just pushes people into packing more densely into the hours that places are opening. If anything, you want to expand opening hours (presumably early opening) to spread customers out as much as possible. The only way I can see this helping is if it discourages people from going out at all.
• Ban pub crawls: this seems to me like a no-brainer, to be honest. Restricting people to a single venue massively reduces the mixing effect. (And it seems likely that there's a strong correlation between pub-crawlers and selfish superspreaders.)
• Track and trace: essential, but only works if you massively reduce your interactions in the first place. If you try and carry on as normal, then everyone ends up potentially coming into contact with an infected person and you have to lock everybody away as a result.
  
• Social distancing: taken as a given, but not enough alone unless you push it well beyond 2 metres. Doesn't matter how far apart you are if you have to share the same door handle, though.
• Face coverings: again, unlikely to be enough on its own. Really, you should be thinking about face coverings, social distancing, and similar precautions as being an extra level of protection if you can't avoid an activity at all (such as shopping for groceries). You shouldn't take face coverings as an excuse to enable you to partake in riskier activities.
• Redefined infrastructure: take the things that we have to do and eliminate risk. Examples include automatic doors (you don't touch anything that someone else has), foot or knee operated taps rather than turning by hand. Individual lifts, and likewise travel compartments rather than massive open carriages.

There's no silver bullet here. Saying "if we all just did X" won't work, no single action is enough. This has to be a concerted attempt, all the options need to be pursued together.

 

I think we could avoid lockdown, but it requires a huge amount of work. You need to go fo the big hitters - working from home as much as conceivably possible, scrapping all large events entirely. Then you need to layer on every single measure and precaution you can. And you need a high level of adherence to make it work.

Sadly, we have a government that hasn't the gumption to do the big things or the eye for detail to do all the little things, and the great british public has far too many gormless prats to expect the measures necessary will be followed.

The accuracy of COVID-19 statistics

Nobody really knows how many people have died in the UK due to COVID-19. There are currently 3 numbers that might give a bit of a clue:

• The daily statistic of those who've died after a positive test
• The number who have had COVID-19 mentioned on the death certificate
• The excess deaths reported compared to a normal year

The last one is more amenable to statistical analysis, but is also subject to a variety of errors: the baseline varies from year to year, and lockdown may increase some types of deaths, while decreasing others (for the latter, consider the reduction in pollution). Still, it's a reasonably well defined number.

The second one is highly tricky, because - absent lots of tests and post-mortems, it's sometimes going to be tricky apportioning the cause of death.

The first one has attracted a lot of attention, and it's the headline number you see in the news. It has the advantage that it's quite well defined (you know, definitively, who has had a test, the outcome, and whether they died). The disadvantage is that it doesn't give you any clue as to whether COVID-19 was actually the cause of death or not - perhaps they got run over by a bus.

Early on, this didn't make much difference. But, over time, the probability that someone would die from another cause obviously increases. So, early in August, the statistic was changed to add a 28-day cut off.

The idea of a cut off is that, very roughly, the number of people who die from COVID-19 after the cut off are offset by those who die of other causes before the cut off. At a nigh level, it makes sense, because otherwise it's going to be wrong, and the error will increase over time.

The question really is whether the correction applied is correct. After all, that 28 days is basically a guess - it's commonly used, so is reasonable for comparison purposes, but it's still a guess.

There are a couple of ways to see if the value for the cut off is reasonable. And for that, we need data. It turns out that we can download the time series from the portal, and have a look at the numbers.

One fortunate thing we have is that the dataset actually includes 3 numbers - raw numbers, with the 28-day cut off, and with a 60-day cut off. As of today, the 28-day cut off removes 6,634 deaths from the starting 44,115, and the 60-day cut off less that half that at 2,695. These are what would come in as deaths from other causes.

First, given the number of positive tests, does that correction look sensible. We know, roughly, that there were ~300,000 positive tests in the first peak. So that's mostly 4-5 months ago. For the 28 day cutoff, that gives a regular remaining life expectancy of 15-19 years to account for the observed deaths. For 60 days, the range is 37-46 years.

The problem with this is that we don't know the demographics of those tested. However (you can look these things up in actuarial tables), for the 28-day number to be accurate, those tested have to be quite old - over 65, whereas the 60 day number would be right for a population of working age - say typically in their 40s. Given that we know that there was little testing in nursing homes, the 28-day life expectancy looks a bit wrong, whereas the 60-day version looks reasonable if you're testing a lot of health workers. It's not definitive, but there's a hint that 28 days is overcorrecting.

Another thing to do is look at the rate of corrected deaths over time. This is what it looks like for 28 days:

and this is for the 60 day data:

There's quite a difference there. Note that our expectation is that the probablity of death from other causes is constant (approximately) over time, so that the overall rate will increase over time (it's constant if there's just a single input at a fixed point in time, but we're testing more people as time goes on so the population is growing - the relatively recent big spike in positive tests hasn't worked its way into the data yet).

From this point of view, the 28-day graph looks a little suspect - it starts to rise 28 days after significant testing, but after day 90 there's a decline. That's plain wrong, indicating that there's a correlation with the time of the test (there are a lot of positive tests in days 30-90 which is when the big first peak was). If they're correlated with the positive test, there's going to be some element of correlation with the cause of the test - namely COVID-19 itself.

By contrast, the 60-day chart has the right shape. The problem is that any large cut off will have the right shape, so it's not telling us anything about the correct number to cut the data at, just that 60 days is beyond it.

The thing is, if you had all the data (inclduing demographics) you could do this properly, and work out what the optimal cut off to minimize errors should be. I just haven't seen that yet. But I'm fairly sure that, while the original quoted numbers overestimated the number of deaths, the new numbers with a 28-day cut off are underestimating the true impact, and they might even be more in error the other way than the original figures were.

What level of response to Covid-19 do we need?

Short version: quite a lot.

The long version below is a rough attempt for me (a former scientist) to understand the problem and the rough nature of possible solutions.

It starts with the R factor - essentially the number of people that an infectious person passes the disease on to. The more people you infect, the faster the disease grows. If you manage to get to a situation where people infect less than 1 person on average, the disease will decline.

I've seen R factors for the UK of round about 3 in the early stages. That's the effective R factor - even then, before our governmenat finally bothered with a form of lockdown, a significant number of individuals and organisations were taking preventive measures. So the intrinsic R factor could be a bit higher, although 6-9 is the highest range I've seen.

As we've seen, the effective R factor depends on reactive measures and behaviour. So what sort of measures are necessary to get R below 1?

Reember, R is the number of people who can pass the disease on to. So you need to reduce that number from anything between 3 and 9 to below 1. Actually, you need to go a decent way beyond that to give yourself a margin of error. So I'm going to say that you need to reduce the likelihood of passing the infection of by a factor of 10, which basically means reducing direct contact by a factor of 10.

And reducing transmission by a number that large is quite a challenge. If you just carried on and tried to use face coverings and social distansing, I don't think you can get there - they might give you a factor of 2 or 3, which isn't enough.

What level of contact do people have with others? I'm going to try and estimate the number of person-hours of contact you generate in a week. Remember, this is before the pandemic.

• Work, you might have 40 hours a week in an office or building with 25 people, giving 1,000 contact-hours
• Commute, You might have 10 hours (1 hour per journey), but cross the paths of 100 people, giving another 1,000 contact-hours
• Play, a restaurant or bar might be 100 people or so for a couple of hours, but you have to get there and back, and might do it several times a week. And I'm ignoring massive events like theatre, gigs, festivals, sports. So that could be another 1,000 contact-hours

That gives 3,000 contact-hours per week, pretty much evenly spread across the 3 categories. And we want to reduce that by a factor of 10 to 300.

Even if you avoid public transport (which has other negative implications for the next major disaster of climate change heading our way) you don't get anywhere near. Carry on as before and drive to work and you only get from 3,000 to 2,000, nowhere near the 300 desired.

As far as I can see, the only way to even get close is to not go in to the workplace, which cuts out the commute part as well. And, in addition, cut down the play component and take all the face-covering and social-distancing precautions when you do.

I see no possible scenario in which widespread full-time return to the office can possibly be entertained as being safe.

Even if we use the idea of only some people going to the office 1 day a week, you're still using up a very significant portion of your contact budget.

Of course, there are those who do need to go to a workplace. There are those who do need to commute. That's even more reason why those who can work from home should do so, to give a bigger allowance to those who really need it.

You can, very roughly, estimate your own exposure. For example, I went out to Ely and had a guided walk with a group of a dozen people or so around the town today. Socially-distanced, including the travel and an outdoor lunch, that was something near 50 contact-hours.