What if we calculated level of service for pedestrians?

As I have said, I am a traffic engineer, my primary job is analyzing and programming traffic lights, or seeing if they are justified. So I've come to learn that in general, the level of service is God. What is the level of service?

Well, it is a letter (A to F) that is obtained through the average delay per vehicle computed either through equation or obtained through simulations. These can be calculated for every hour of the day, but for evident reasons, they are generally only calculated for two hours, the worst hour of the AM peak and the worst hour of the PM peak, where traffic is highest. Sometimes, off-peak traffic is also analyzed.

How it works is that you suppose a car driving at the desired driver's speed (often 10 km/h over the limit) and calculate how long it would take to clear a certain section of road if they didn't have to slow down or stop. Then, you add the intersection and the control mode (stop signs, roundabout, traffic lights), calculate how long it takes the vehicle to actually make it through that section of street, the difference between the desired travel time and the actual travel time is the delay. This is measured in seconds per vehicle. So if you have 500 meters and a driver wants to drive at 60 km/h over that section, he could do it in 30 seconds, but if in the simulation it takes him 50 seconds to do so, then the delay is 50 seconds minus 30 seconds, so 20 seconds.

Largely in order to avoid discussions over a half second difference or the like, delay is converted into "level of service". The level of service is considered worse for a given delay on unsignalized intersections (stops signs or roundabouts), representing greater user frustration when facing long delays at these intersections.

Note that level of service for say highway interchanges and straight roads without intersection also uses A to F but is calculated differently, generally with the density of vehicles rather than the delay.

The objective of a traffic engineer in most studies is to keep level of service as low as possible to avoid delays for drivers, helping them drive faster and have to wait less for other traffic.

Now then, some of you may ask "well, what about pedestrians and cyclists? How is level of service measured for them?"

Well, the answer to that is that the default method says: Fuck 'em.

OK, that's hyperbole... It's not like the norms say to ignore them, no, they recommend accommodations to help them cross the intersection but there is no metric for level of service for pedestrians or cyclists. The dominant mentality is quite clearly "Pedestrians and cyclists should be happy to even be ABLE to cross the street, their time is not valuable at all... else they wouldn't be walking/biking".

Now, cyclists according to the norms should act like vehicles, so in a way, they could be expected to have the same level of service as cars as they should follow the same signals. But that's not the case for pedestrians. So follow me, if you want, through a thought experiment:

What if we measured a Level of service for pedestrians?

So let's suppose that we calculate a level of service for pedestrians based on the same basis as for vehicles. Pedestrians can stop and accelerate to regular walking speed almost instantaneously and so we don't have to calculate delay caused by lower than desired speeds during acceleration and deceleration. So delay is limited essentially only to the wait time before they can go ahead and cross (supposing car drivers respect pedestrian priority). Let's look at some particular cases.

Crosswalk

A crosswalk theoretically gives priority to a pedestrian as vehicles are supposed to stop when a pedestrian wants to cross. In reality... that rule is not always ignored, but its respect depends a lot on how the crosswalk is designed and if the police cracks down on delinquents. The narrower the crosswalk is, the more respected it is, if you have neckdowns, it will be more respected, if there are signs placed in the middle of the road to indicate the crosswalk AND the fine for disrespecting it, it will be more respected. But wide crosswalks on streets with 4 lanes without special signalization are not much respected, and sometimes even dangerous, because even if one car stops, the other coming in the other lane may not.

Anyway, if we suppose that a pedestrian needs 6 seconds without a car passing on the street to be able to start crossing and assert his presence, then a statistical calculus allowed me to calculate an approximate delay and LOS depending on vehicle flow (supposing this vehicle flow as the sum of flows in either direction, possibly reduced if there are 2 or more lanes per direction):

So crosswalks work best when traffic is below 900 vehicles per hour (again, sum of both directions) at peak hour. Note also that if the crosswalk is badly located and requires detours, for instance on high-throughput roads, if there's a crosswalk every 500 meters only (about a third of a mile), this may inflict an average detour of 2 or 3 minutes per pedestrian... as a level of service of F is 50 seconds and more for unsignalized intersections, that's an automatic F. Any detour of more than 80 meters is an automatic F (that's about 270 feet).

So crosswalks work best when traffic is low and when there are no detours... in short, when jaywalking on narrow, traffic-calmed streets, rather than actual crosswalks. To help crosswalks perform better, medians are a great idea as they allow pedestrians to treat a street crossing as crossing two one-direction streets in a row, for instance, if you had a street with 600 veh/h in one direction and 400 veh/h in the other, if a pedestrian has to cross it in one time, the delay could be around 35 seconds until he got an occasion to do so. But with a median, the average wait time will only be 15 seconds or so as he can cross each direction one at a time.

A median allows a crossing to be made in two legs, reducing waiting times and making it safer, with a median, even arterials with high traffic flows and 2 or 3 lanes per direction can easily be crossed by pedestrians

A pedestrian refuge can achieve the same goal when you don't have the space for a median all along a street

Roundabouts

Roundabouts  are actually covered by crosswalks as pedestrians have to cross each branch one by one. This is not as bad as it sounds as these crosswalks tend to be split in two one-direction crossings rather than one longer crossing, and cars go at low speed in roundabouts and in their vicinity. Still, there is an additional problem with it being hard to know if cars in the roundabout are going to exit or not as most people don't signal their exit from a roundabout.

A bigger problem is the detour for pedestrians who just want to continue on ahead.

So, like crosswalks, roundabout performance is linked to traffic flow. The higher the traffic, the worse for the pedestrian. Also, detours for straight movements make roundabouts in most locations not that good for pedestrians, unless traffic is very low. Expect a level of service between C and E.

Stop signs

Stop signs are, of all the ways of controlling traffic, probably the single best for pedestrians. Like vehicles, they have to wait their turn, but unlike vehicles, pedestrians do not go only one at a time, if a group of 10 pedestrians arrive at the same time at a crossing at an intersection controlled by stops, they will not go one by one, but will all cross at the same time. The most they are likely to wait is 10 seconds, waiting for 2 or 3 vehicles to do their movement before doing theirs. That is a guaranteed level of service of A. The only detour worth mentioning is the diagonal one for pedestrians who have to cross two streets instead of going diagonally.

However, there is a caveat. At intersections of streets with two or more lanes per branch, especially ones where streets do not meet at a right angle, safety suffers as drivers may be overwhelmed by the number of lanes and sidewalks to check all approaches and corners before moving.

Traffic lights

OK, now for the big one. How are traffic lights for pedestrians? Largely, except for a few cases with narrow streets, pretty terrible.

The reason is that wide intersections take a lot of time to cross, resulting in long phases and thus long waits to get their signal telling me to cross. If you look at car signals, you have the usual three lights, a green light to tell cars to go through, a yellow light telling cars to finish their maneuvers if they can't stop safely and a red light to tell cars to not enter the intersection anymore. But since cars are so fast, the yellow light and all-red light are very short. So a 30-second traffic light for cars look like this:

25 seconds of a green light

4 seconds of a yellow light

1 second of all-red light until the next phase starts

Meanwhile, given that intersections with traffic lights are often built very wide to add turning lanes and increase vehicular capacity, and to allow trucks to turn. The result is that crossings at intersections are much longer than the width of the street further out.

For example, here is an intersection in Boucherville, my home suburb:

Note that the street is just 16-meter wide (around 50 feet) far from the intersection, but the crossing of that street at the intersection is 25-meter wide (around 80 feet). While it would take 10 to 12 seconds to cross the street by jaywalking farther away, it would take 20 seconds or more at the signalized crossing at the intersection.

What this means is that often, a 30-second pedestrian phase would be split in two:

A 5-second WALK phase during which pedestrians can start crossing

A 25-second DON'T WALK phase during which pedestrians that are in the crossing can finish crossing, but those at the sidewalk are told to stay there and wait for the next light cycle.

This symbol, but flashing

The DON'T WALK phase is calculated by dividing the width of the crossing by the average walking speed (for a slower-than-average walker, around 1,1 to 1,2 meter per second, or around 4 feet per second, but sometimes, near hospitals and elders' homes, it can go as low as 0,8 m/s, or less than 3 ft/s). The WALK phase according to the norms is 5 seconds, more if there are a lot of pedestrians. But when we can, we give more time to it (for instance, if concurrent with a green light that lasts a minimum of 40 seconds and the DON'T WALK lasts 20 seconds, we'll often give 20 seconds to the WALK phase).

So let's take a typical traffic light phasing, with protected exclusive left-turns for the main road, and coordination to lower vehicle delays by synchronizing traffic lights (very frequent on arterials).

So while vehicles have the right to enter the intersection 86% of the time, pedestrians have the right to do so only 23% of the time, and that's an optimist case where the engineer increase WALK time during the THROUGH phase for the main road, if he didn't, then pedestrians would have the right to enter the intersection less than 10% of the time.

In this case, we can easily estimate delays. For pedestrians crossing the secondary road, they have (20/110) 18% chance of not waiting at all, and 82% chance of having an average of 45 second delay, so a delay of 37 seconds. That's a level of service of D.

For those wishing to cross the main road, they have only 5 seconds of WALK on a cycle of 110 seconds, so they have less than 5% chance of waiting 0 second, and 95% chance of waiting an average of 52,5 seconds. That means an average of around 50 seconds, also D, but getting pretty close to E, which is a level of service that is often deemed unacceptable in traffic studies for vehicles.

Those who do the two crossing can expect to wait about 55 seconds, entering E level of service.

In my work, I've frequently seen traffic signals with cycles of 120 to 160 seconds on arterials. These basically guarantee E levels of service for any pedestrian crossing the main street. This delay represents the equivalent of nearly 100 meters of walking distance, losing about a minute per intersection. And while cars can have synchronized lights, pedestrians don't have this chance. So if you have 4 traffic lights in a row, cars traveling along the main road can expect to have to wait at only one or two of these intersections. Pedestrians can expect to face an average delay of 30 to 45 seconds on each light, that means 2 or 3 minutes of delay.

Even worse, sometimes you have intersections where particularities compel traffic engineers to remove pedestrians crossings on one or two branches, like for instance when you have two left-turning lanes:

This intersection allows pedestrians to cross only the northern approach (Taschereau Boulevard in Longueuil)

This forces pedestrians to do THREE crossings. Needless to say, most pedestrians refuse to do so and will often cross without signals.

Pedestrians buttons can compound the issue, when pedestrian phases aren't in RECALL mode (always happening every cycle), pedestrians who normally would arrive during their WALK phase may not even have it because of the need to push the button (often called the "beg button" by urbanists).

The best case scenario is an intersection with very narrow branches with simple phasing (green light for main road, green light for secondary road), which even then will likely give a level of service of C to pedestrians. But if traffic flows increase, the cycle will have to be increased, increasing delay for pedestrians.

Conclusion

Crosswalks provide good levels of service to pedestrians only when traffic flows are low (but allowing jaywalking work better in these cases) or on narrow streets with special amenities. Stop signs provide excellent service to pedestrians, having next to no delay for them. Roundabouts are middling for pedestrians, forcing them to go around the roundabout and to cross many crosswalks (even if they are relatively easy to cross). Traffic lights, especially on the wide arterials we have so often built in suburbia, will impose important delays to pedestrians, especially those wishing to cross the arterial, who will frequently have a level of service of E (at least, they would if we bothered to calculate it). That's not even talking of issues of safety.

So what does that mean? That means that crosswalks with medians and stop signs should be preferred to traffic lights for areas with a focus on pedestrians. It also means that the habit of channeling all the traffic on a few wide arterials, forcing each intersection to have multiple turn lanes and many through lanes, is absolutely terrible for pedestrians. A street grid with densely packed streets would do a better job of responding to all users, as it would dilute traffic on many streets, all these streets could be narrow, with 3 or 4 lanes only (1 per direction plus a shared left-turn lane or 2 per direction). Ideally, I believe there should not be any width of pavement greater than 12 meters (40 feet) in a city, any pavement wider than that should be broken in two with a median wide enough to use as a pedestrian refuge.

To return to my original question: what if we accounted pedestrian delay and level of service? Well, it would have little impact on intersection performance, which averages the delays of all vehicles on all approaches. We have been so great at repressing pedestrian movements through a focus on motorized transport it is rare to see more than 100 pedestrians a day on most arterial intersections outside a few dense cities. Not surprising when these arterials serve as walls in developed areas, barriers to pedestrian and cyclist trips.

Note that there is also the possibility of shared spaces, as interesting and effective as it may be, resistance to them is high in North America and most arterials are not fit for them (shared spaces work with low speed and low traffic flow, without trailer trucks... most arterials in North America have high speed, a lot of traffic and plenty of trailer trucks).

Prince Charles' 10 principles of urbanism: typical example of what's wrong with urbanists/architects

Recently, Prince Charles published an essay about 10 principles for sustainable cities, which has made some waves. Which can be summed up as follows:

1- Developments must respect the natural land they occupy and not be too intrusive.

2- There must be a building code to follow geometric rules for architecture.

3- Buildings must be built to the scale of humans and of the existing area.

4- Buildings must be harmonious and have a coherent image.

5- The built area must provide enclosure.

6- Buildings must be made of similar materials in a given area, preferably locally sourced material.

7- Street signs must be reduced as much as possible and utilities must be buried so that you can avoid having them intrude over the look of the area.

8- Pedestrians must be the focus of streets, not cars.

9- Density is important but must be done through low-rise buildings (townhouses and low-rise apartment buildings).

10- Flexibility rather than imposing exactly what goes where.

First of all, I do not share some people's dislike of Prince Charles. I do think his heart is in the right place. That being said, I think his approach, well-intentioned as it may be, is a good example of the main flaw common among many urbanists and architects. Namely, they care about urban areas that satisfy their own subjective aesthetic criteria almost to the exclusion of everything else.

In effect, they consider cities more as museums or art galleries than areas in which people live and work.

At the same time, they often like cities they can walk in, so that alone makes them better than the modernists of years past who preferred to experience cities through models, the windshields of cars traveling along expressways and the windows of high-rise offices. But there is still a bit of narcissism here, the idea that cities should be built to satisfy their tastes first and foremost, no matter the cost.

And here's the main issue here...

Urban policy is not just about architecture, it's also about economics

You'll note that there is a big absence in his 10 principles: the words affordable and affordability are nowhere to be found. Yet these are extremely important factors, though one I understand a royal heir is unlikely to have a personal acquaintance with. No matter how great the areas you build are, if most people can't afford to live in them, only a privileged few will get to experience them to the fullest.

Indeed, in his quest to get areas that conform to his aesthetic taste, he came up with quite a few principles that are going to make housing unaffordable. Namely, the principles 1, 2, 3, 4 and 6 are likely to directly increase the cost of building new homes. Every restriction made upon new buildings increases the complexity of approval processes and therefore the cost of getting building permits, costs that will be reflected into the value of new buildings. His principle about the control of materials is also likely to create shortages of these materials, thus increasing their prices, and thus, the costs of construction.

His principles 1, 3 and 4, asking for harmony between buildings and limiting scale also directly contradict his principles 9 and 10. Indeed, it is easy to sum up these three principles as "protecting a neighborhood's character", a common euphemism of NIMBYs for: "no development allowed". Existing areas can thus not increase density without directly running into his principles for harmony and scale preservation. Any development that is higher density to existing buildings will ALWAYS represent a break in the existing "scale" of the built area. As a result, the only way to build new density and respect those principles is to build a dense greenfield development on the periphery of existing areas. Which is absolutely insane, because then these areas are disconnected from existing dense areas and likely to require cars to travel around. Rapid transit can help mitigate the terrible location, but only to some extent.

Forbidding density in existing areas also mean that you cannot increase housing supply in areas where there is a shortage. So the shortage is just going to get worse and worse, pushing all but the richest away to areas that have bad urban design.

Neo-traditionalism: outcome or process?

Prince Charles is clearly a traditionalist who likes the traditional cities of his native land. What he doesn't seem to understand, like a lot of urbanists and architects, is that these cities didn't spring in that current form in one day. They are the result of incremental development over the years, with denser buildings replacing earlier ones (often with a little help from our buddy fire). They were not planned this way, they spontaneously evolved to their current form.

Yet, if Charles likes the outcome of this traditional city, he clearly doesn't like the traditional process through which these cities came to be, he would like to plan things out ex nihilo rather than see them evolve over time. Considering the new materials and technology available to developers, turning our back on anything that was invented after the 19th century seems foolhardy at best. The traditional process that created traditional cities is not incompatible with new building forms and technologies, there is no reason to shun them.

In a way, the true descendants of traditional cities aren't the mummified European cities of Paris and London where all is done to maintain buildings and neighborhoods as they were in the early 20th century, but Japanese cities. Yes, Japanese cities are resolutely modern in terms of buildings, but the traditional process of city-building is still alive in Japan, while it has been replaced by planner fiat in Europe and North America. The people who built the cities people love would have likely been more than happy to have our modern technology to allow for taller buildings with more varied materials. Likewise, though the Japanese use modern materials and technologies, they still use them in a way that is more in line with the traditional process of incremental city-building. The opposite of Europeans who use traditional materials and technologies but have a strictly modern planning system to control their urban developments.

So, all in all, I would say that we need more pragmatism and less artistic "integrity" in urban development policies. Any regulation to satisfy subjective aesthetic criteria should be analyzed to see how they impact the economics of urban development, and they should only be applied if they have no impact or only minor impacts on affordability. Prince Charles' principles come from, if I may say, a radical perspective where aesthetics matter above all else, a flaw that is only too common in current urbanists and architects and result in cities that are supremely expensive to live in, with people of modest means forced to live ever farther from the central areas and to commute ever longer distances.

Reflecting on the concepts of streets

In urbanist circles, the modernist architect Le Corbusier has become sort of a boogeyman, whether or not that representation is fair or not is up to everyone to judge (I personally think it's rather fair). One of the most  One of the most damning quotes we hear from him is "death to the street". The street is generally seen as the defining place of cities, so that is completely heretical for most urban-minded people.

However, I have to correct the quote. The real quote is "Il faut tuer la rue-corridor", "we have to kill the street-corridor". Already, this adds a certain nuance to his comment. A corridor is a part of a house that only serves to connect different rooms, it is merely a place of transit, narrow and frequently without natural light.

Reading the real quote made me think about streets and about how different cultures at different times approached it differently. Again, disclaimer, this is me thinking out loud, if I take a seemingly authoritative tone sometimes, that is just my way of speaking neutrally and not a claim of authority. I am open to the idea of being wrong.

So let's start.

The street-corridor

So what was Le Corbusier talking about? Well, if you check out old European cities, you would notice that streets are indeed very narrow, only the strict minimum required to let people and vehicles through. When the street ends, the buildings begin, there is no space between building and the street (including the sidewalk here). As a result, there is no semi-private area, you have a pretty drastic contrast between public space and private space. As a consequence, unless you have stores on the first floor, you have very inward-looking buildings, where there is a distinct lack of windows facing the street on the ground floor, very rare balconies and often shuttered windows.

A street in Marseille, France

The area of the first picture seen from the air, notice the relatively large courtyards compared to the narrow street

Even some more recent developments have kept this attitude of putting a narrow street with homes with closed fronts, but huge backyards. Like this example in Amiens:

Amiens, France

Same area, seen from the air. I am not kidding.

Streets also seem quite narrow, to serve essentially as a way of getting from point A to point B. They could still become interesting places if buildings on either side house ground floor shops and restaurants, as these places are open to the public and form kind of an extension of the street.

I think in a way, what defines the street-corridor, more than width, is the clear limit between public and private space and the use of the street mainly for transit. In that way, the street is often made only as wide as it needs to be, because it is largely seen as a necessary evil to provide access and the narrower it is, the more space can be given over to private uses. Though buildings front the street, they are generally closed to it. Which actually means that streets like these...

6th avenue in Calgary

...have a lot in common with the previous streets, except the scale is different as it is built for car transportation rather than pedestrian traffic. But otherwise, both have buildings that are closed to the street, a clear delimitation between public and private space and a street serving through traffic rather than serving as a place.

The street as common space

This is something that is particularly common in North America. Nathan Lewis on his blog refers to North American streets as "hypertrophic" and notes how wide they were built even before cars came. Contemporary documents seem to reveal that the streets weren't completely unused, though they were much wider than necessary for transport, they seemed to have been used as a sort of communal front yard and playground for residents. Often, this came with a reduction of private space, through smaller back yards.

An older area of Pittsburgh

Philadelphia

Philadelphia

Houses are often more open to the street in these areas rather than closed on themselves, there are more windows at ground level and some buildings have small porches or balconies and other attributes that favor a smoother transition between the public space of the street and the private space inside the houses.

Rosemont in Montréal

In the last case, there is some small setback between the houses and the sidewalk, which protects the privacy of houses without requiring them to close down and provides for a private space that is nonetheless visually part of the public realm of the street. This provides a façade, a way for residents to display their personality to the community passively by how they maintain this private portion of the public realm.

Now, when motorization occurred, these wide expanses of common spaces vanished from cities, being taken over by cars, whether in movement or parked, depriving city residents of this public space and kids of their playground. It would be hard to conceive of wide streets used that way nowadays, as they would likely host parked cars or have traffic at high-speed unless there was particularly effective traffic-calming deployed.

It makes me wonder if, at least at first, suburbs with low density and off-street parking requirements were built to preserve this function of the street. For instance by allowing kids to play hockey in the street (or stickball in the US), thanks to low traffic and the absence of parked cars on the asphalt.

BTW, anecdotally, my mother has many French friends from when she taught a few years there. When she invited them to our sleepy suburb, her friends were amazed by how open the houses were to the street and that people on the streets could, if they wanted, look inside the house. So, ironically, though North American countries are considered more individualist than Europe, the built environment of North America is in a way more oriented towards the community, with private residence being more open to the neighborhood.

The street as a park/forest path

This is an anti-urban conception. In this concept, the street and private houses are separated by a large buffer with plenty of trees along the street, in order to really separate houses and street and preserve the feeling of being in a park or a forest even if you're in a developed area. The goal is largely that the street should not be seen from the building, nor the building from the street. The result is a disconnection between developments and their lots, with little or no urban fabric, even when the area is high density (the famous towers in parks). A trick that is sometimes used in these developments is to have buildings at an angle or perpendicular to the street.

A street to secondary houses in the Laurentides region

A collector street in an Houston suburb

The same street seen from the air, suburban cul-de-sac developments connect to it

Another street near the area

And now for the denser examples:

Would you believe this area of Stockholm is 200 meters from a metro station and is densely populated?

Well, it is.

Seeing Stockholm in Google Maps is quite interesting because it has a rather unique form of development. In a way, Stockholm's suburbs are a bit like a transit-oriented Texan suburb, with developments self-contained in semi-cul-de-sac, connected by streets that look like forest roads. The big difference is that most developments are much higher density and have access to transit, either buses, trains or trams. Each of these developments seem to have a specific building type, which seems to bear the mark of strong centralized planning. The street grid of Stockholm consequently completely breaks down outside the core urban area. If anything, it proves that this kind of development can result in transit-friendly cities, as Stockholm's transit mode share is extremely high, 35%, but walking is much lower at 17%. (Source)

Here is another example, Moscow, where the communist leadership liked the "tower in the park" concept.

The big failing of such a treatment to streets is a tearing of the urban fabric and the loss of "eyes on the street". Since the street is isolated from the developments, it becomes much less secure, especially at night.

Conclusion

Not really any conclusion here. This is a pure case of thinking aloud about how different cities and cultures build and conceive the street in relation to developments, whether developments front the street, whether these buildings are open or closed to it.