January 2021 - Edition 21, Suburban Mass Transit


It’s been a rollercoaster of a month, but it looks like it all settled out in the end. We’re still in the midst of a pandemic, but the tides are turning and perhaps the sun is starting to shine.

Demetri's Corner

The new year has come in busy. Between trying to stay sane with kids not in school for seemingly a decade, getting work done and a new puppy, it has been a whirlwind. I’ve come to the end of the month and realized that I had not written a newsletter, so the time has come to buckle down and pump out this edition.

A few newsletters ago I starting a series about mass transit. It was always my intention to break it up into the different ranges of travel and started with the smallest distances – those in urban centers. Moving out from that urban core is the suburban community. Suburban mass transit is a very unique concept in the United States, so that makes this a freeing experience. Without a lot of precedent, I can feel free to consider it almost “fresh” and see where it goes. Next in the series will be regional transportation – as in between major metropolitan areas.

Today's Subject - Suburban Mass Transit

The concept of suburban mass transit will seem relatively new, especially to Americans. Having lived in a suburb of Athens, Greece, the concept is very real. Many people commute from suburbs to urban centers to either transfer to an urban transit system or at their final destination.

In Edition 16 of the SES Newsletter I tackled the concept of urban mass transit. That discussion was about how to get around a city core (narrowly defined as a high density, small footprint area) in the most effective manner. While that discussion covers a great percentage of the population around the world, it would leave many people without transportation that live close to urban centers but out of reach of these highly efficient short range systems.

This newsletter focuses on getting people from medium distances into an urban core where many of the work, shopping, and governmental functions occur. This is particularly important in the United States where the car culture mentality has led to cities that are organized around distances that are awkwardly out of reach of city centers. I will be using the same format that I used in Edition 16 for continuity, starting with a definition, moving on to attributes of good systems, then looking at some current and future approaches. Since much of the information is repetitious, I summarize it greatly and referencing Edition 16 will provide additional details and insight.


The term “Suburban Mass Transit” is not one I commonly see, so we must take some pains with defining the scope. The ultimate goal of this entire series is to provide a means for anyone to have efficient access to work, shopping, recreation, and government services without using a car regardless of location. The suburban system would have to expand the range of transit from the urban center out into the areas where housing is located and more dispersed. To establish the basis for what this means, we’ll look at each term individually.

Suburban – Webster’s defines suburbs as, “towns or other areas where people live in houses near a larger city”. This isn’t especially helpful when defining a transit system as we need to have some sense of the distances. Practically it’s a place where people live that have some reasonable expectation of efficient access to the associated urban area. This can mean different things in different countries, but I will use my personal experience living in the United States as the basis. I would contend that reasonable expectations people have when selecting suburban life is that their commute with a car is 20 minutes. We generally make these decisions forgetting about traffic, so the distance relates to “no traffic” speeds, or around 55 miles per hour on average. That means that as a populace, any housing within 15 or so miles of an urban boundary would define the suburban area of interest. Obviously this is a very generic understanding, but it provides some basis for the scale of the transit system.

Mass – A great many. For a suburban environment, this is a lot more people than many realize. The area to be covered is vast, and suburban areas by definition have a lot of housing. With population densities of 2000 people per square mile possible, and a land area that may be over 2000 square miles, there could be 4 million people housed in the suburbs.

Transit – Fairly self-explanatory. A system of conveyance. But more than that, a functional system that is better than nothing. By functional, we mean a conveyance that does not result in excessive commuting time and inconvenience.

Critical Attributes of a Good Mass Transit System

This is a duplicate of the critical attributes in Edition 16 of the newsletters with minor variations to make it more applicable to suburban mass transit.

Gets you where you need to go

It’s pretty obvious that for any mass transit system to be considered “good” it has to go where you need it. That means that you can reasonably pick it up from your starting point and ride it close to your destination. “Reasonable” is certainly subject to debate but should be based on easy accessibility in all weather.

Cost effective

For the transportation to be “for the masses”, the cost must not be prohibitive for the vast majority of users. It’s hard to determine what would be prohibitive, but let’s roughly calculate the cost of using a car. In Edition 16, the per mile cost of car usage was estimated to around $.70/mile. Using this same metric, a 15 mile suburban commute would cost $10.50. It’s rational to believe that there may be additional transportation costs associated with being carless, such as the use of rental or hired vehicles. To offset that cost, the system should be cheaper to compensate, so a cost of less than half would be appropriate.


The first point would seem to fall under this category, but really this is the next level of discrimination. A mass transit system that requires climbing flights of stairs to a monorail platform, or has you waiting in the rain technically meets the requirements of “gets you where you need to go” but could not be considered especially convenient.

Convenience is about whether it’s easy to use. There is no real comparison with personal transport since in that case you have complete control over accessibility and availability (in the most part) given enough funds. Therefore we access appropriateness on a qualitative level.


Ideally a mass transit system would leverage the efficiency of scale and use less energy than a bunch of cars. Any mass transit system that causes more harm to the environment than the car alternative would be considered a very poor system indeed. It is generally accepted, that when compared to gasoline engines, this will be an easy wicket to meet, but with the prevalence of high efficiency electric vehicles, the gap may be narrowing.

Review of Current Approaches

There are essentially two approaches taken for mass transit. The first involves conveyances that operate on a fixed infrastructure, such as a track, tramway, or connected to overhead wires. The second is based on conveyances that have a generic interface with existing infrastructure, such as buses, scooters, or hired cars. We could talk about all of these, but the most prevalent of the two approaches are considered in this section for illustrative purposes. For fixed infrastructure, we will consider a light rail system, and for existing infrastructure a standard bus system.

Light Rail

For our purposes we will consider light rail as a set of trains riding on narrow gauge track above ground. Pickup points would have to be available approximately every mile or so to allow for easy walking from a house to the stop. We should anticipate that the train schedule is going to depend on the time of day as the suburbs are about commuting and most will only require transit intermittently in off-peak times. I have little experience with light rail but using the Los Angeles Metro A line seems to meet our distance metric and speed.

Does it go where it’s needed? – It very well could, but the nature of a fixed rail system means that it is hard to change. The suburbs are constantly building out new areas and abandoning old. It is hard for a fixed infrastructure system to keep up and maintain service to the locations needed. Due to the nature of the suburbs, a great number of tracks will eventually be needed unless there are intentional measures put in place to ensure new construction and availability of transit infrastructure are coordinated.

Is it cost effective? – Based on the trip cost for the Metro A line, it is very affordable. At a cost of under $2, using the light rail is well below that of car ownership costs per mile.

Is it convenient? – That’s pretty variable dependent on the time of travel, the train you’re using, and the stations associated. The major consideration for light rail is that a trip the entire length of the Metro A line (which is about our target for a maximum commute distance) can be nearly an hour. Add to that a five minute wait at the station and ten minute walk from your house and convenience is not the first thought that comes to mind. The primary reason for this travel time is all of the stops. The train itself is more than capable of speeds that eat up the distance. Stopping dozens of times not only makes the average moving speed slower, but means less consistency in the train schedule. The only real solution to this problem is to have trains that service only a few, spaced out stops, effectively leapfrogging each other so the transit time can be reduced. I haven’t seen this specific approach, but it is similar to the express bus and subway systems seen in some cities.

Is it good for the environment? On this count, it probably is since it’s powered by electricity, and runs on a low rolling resistance rail system. Without specific analysis there’s no way of knowing, but I’m hard pressed to believe that the environment would rather have all of those people driving.


Since buses are pretty generic, we’ll assume the best on how the system is implemented in a suburban area. That means some dedicated bus lanes, established and centralized stops, and the use of hybrid technology.

Does it go where it’s needed? – Assuming good city and transit system planning, this should be a slam dunk. In an ideal scenario where mass transit is prioritized, buses can go anywhere a car can go, making this a flexible alternative and serving any area needed, even as new areas are developed.

Is it cost effective? – Generally busing is one of the cheapest forms of transit. The infrastructure is already available, so you’re only paying for the conveyance and energy.

Is it convenient? – The discussion with light rail applies here. The limitations on speed due to the number of stops must be addressed, but the flexibility allows for more dynamic application of buses to meet demand and adjust schedules and routes. The one major differentiator from a light rail system is that buses often use the same streets as cars. Without providing the bus dedicated bus lanes and signaling, a more established light rail system may be able to move more efficiently. Note that by dedicating the lanes and signaling, you essentially morph the bus into an infrastructure dependent transit system – albeit much easier to modify and update as needed.

Is it good for the environment? – In most cases a well maintained bus with modern technology with a moderate number or riders will use less fuel than an equivalent number of cars. But it stops and starts a lot (the most energy intensive portions), is not especially efficient (heavy vehicle on rubber tires), and is often not filled to capacity. A bus that is only moving two people is not going to be better for the environment than a couple of cars. And in traffic, buses idle just like a car, one of the largest sources of urban pollution (though hybrid systems have come a long way). Use of technology that tells a bus whether it actually needs to stop may be a very valuable means in maximizing bus usage, density, and minimizing inefficiency.

Some Currently Proposed Approaches

Beyond what is normally seen, there have been some innovations that could qualify for mass transit if properly applied. We’ll look at each of these as well.

Personal Rapid Transit

Initially this was envisioned as a system of individual tram cars that come on demand and take you directly to your destination. A hybrid of a subway system and a hired car service. It’s rarely been implemented due to a number of technical issues. More recent thoughts have considered the use of automated vehicles that use existing infrastructure – negating some of the technical issues previously encountered. That seems like the more promising approach, and more applicable to the suburban environment.

Does it go where it’s needed? – Assuming automated vehicles that drive on existing roads, it goes exactly where it’s needed and nowhere else. There may be some limitations on the automated technology precluding it from going down some streets, but given the rate of advancement, it’s unlikely that a compatible street will be that inconvenient.

Is it cost effective? – Since no real system exists, we have to make some pretty big assumptions. Generally each automated vehicle is essentially a car, with the same fuel and maintenance costs and potentially no higher traveler density. There might be lower insurance costs, but likely that would be offset by cleaning costs and premature wearing out of publicly used vehicles. It’s unlikely that the cost would be much different than the $.70/mile we estimated for a personal car. And someone has to make profit, so it would likely be more expensive per mile unless it is subsidized (which is very likely, as would be any other public transit system). Without further information, we’ll call this a wash.

Is it convenient? – In a suburban area, the ability to get picked up at your house is unique to this mode of transport and extremely convenient on that point. That convenience of pick-up location comes with some caveats. It may not be “accessible” such as for wheelchairs. Availability could very well be spotty, especially during commuting times when transit is the most important. Remember that everyone in your neighborhood is looking to go the same direction at the same time, and the round trip could take an hour. One would think that it would be cleaner than a bus but imagine all the things you see riding on a bus. If the same people used these vehicles, why would they be neater all of a sudden (or smell better)? As it’s more private I can only assume their hygiene would be worst. And worse than that, you’re stuck with whatever you get when it comes to pick you up for the whole commute, so you get to spend your ride marinating in the juice of the previous occupant.  So even though the pick-up aspect is promising, using this means of transport for long distance commuting overall is rather inconvenient and icky. Not to mention it does nothing to change congestion on the roads, so your commute is probably longer.

Is it good for the environment? – This is essentially our current situation, but with automated cars. Some efficiency may be gained by coordination, but the gains would be small relative to the gains of a rail or bus system.

Increased Bicycle Infrastructure

This one is a little bit of a cheat as I’m only talking about making the infrastructure to support bicycle commuting. For these types of distances, I’m really talking about using electric bicycles. This option is available to anyone that has their own bicycle, or uses a rental bicycle.

Does it go where it’s needed? – At first blush the answer is yes, assuming you treat bicycle routes with as much importance as current car routes. If you don’t have your own bicycle, then you are at the mercy of rentals, which may only be provided at some locations. At the other end of the line you have to find a place to store your bike or a place to drop off a rental.

Is it cost effective? – This is almost certainly “yes”. The equipment is relatively cheap, the fuel is cheaper, and the infrastructure is less than creating dedicated bus lanes and signage. Per mile it’s hard to beat.

Is it convenient? – This is a solution that only works well when the weather is good, and dependent on the location and time of year can be incredibly limiting. Some will argue that you can bike in all weather (I have), but realistically only a small subset of the population will choose to ride a bike in driving rain for 15 miles. In terms of availability, there are two worlds. If you own your own bike, it’s always available like a car is now. You still have to find a place to put it at your work, but the size of a bike makes this a pretty trivial consideration. If you are using a bike rental system you start to own all of the problems of availability that come with the personal rapid transit system – but worse. Not only is the demand one sided, but there’s no way for the bicycles to return themselves to where they are needed, so they are going to spend a lot of time stranded and underutilized. If you really think about it, you essentially need a one to one ratio of rental bike commuters to working rental bikes in the fleet to make this even viable.

Is it good for the environment? – Due to the low energy usage optimized for the size of the vehicle, it’s the most energy efficient solution on average. So yes, it’s good for the environment.

Addressing the Issues

Both light rail and buses are primarily challenged because of lack of convenience. This isn’t about going where it’s needed (properly designed these systems can address that consideration), but the speed of the commute. This is not news. I’ve heard a lot of arguments against mass transit systems, but the only one I have to accept is valid is that often they take significantly longer than just getting in a car.

For suburban transit, new and innovative ways of using these services are necessary. Often these types of systems are “lower tier” that transit systems serving the urban areas. Not enough effort is put into making them efficient. I see the use of express subway lines, alternate route service, and many other time saving strategies in subway systems, but rarely do you see an express line bus that isn’t stuck behind the local or a light rail that goes by stations without stopping. To be truly effective, these types of transit need relatively few stops per line to effectively cover the distances required and still be time efficient. This means having overlapping routes and integrated planning and deployment, which is a step beyond what is normally available in suburban areas.


Mass transit for suburbia is a challenge that is not often thought of. And it’s a hard challenge since there are so many variable and different opinions. Given what is currently available, we could develop express bus routes that serve neighborhoods and get them to an urban transit center. These do exist in some cities, but to make them truly effective the buses must run independent of all other traffic, essentially making them land trains. Ironically there is plenty of space and roads already in suburban areas to do this, but that means taking those roads away from cars.

But even with this rosy view of what buses can accomplish, the sprawl of suburban areas is a real problem. We’ve covered that the only way buses can be competitive in the factor of convenience is to limit the number of stops. That means stops are few and far between. This is where one of the upcoming trends could really play a role. Imagine a bikeway network that connected neighborhoods to bus loading centers. Think of them as park and rides for your bike. Then many of the benefits of bicycles are realized (low cost, easy access) without the downfalls of a bike commute (long rides in bad weather, the need for an enormous number of rental bicycles).

Dose of Aphorisms

This newsletter covered a type of mass transit often overlooked. We think about urban mass transit, and we think of long distance mass transit. We rarely think about how people get from their white picket fence house to their office in the city. That’s because most consider this problem solved by cars. Recently we’ve come to realize that actually we’ve been covering up the symptoms of some bigger issues with our large, energy intensive hunks of metal. And the longer we avoid fixing the problem by covering up the potential ramifications, the worst the problem gets unchecked.

Removing cars from the road is one of the key ways we can reduce our energy dependence and slow down the rate of damage to our planet – and most of those cars are used for exactly the commute addressed in this newsletter. Clearly none of the current approaches have gotten traction to date. This could be because of politics, societal pressure, or even that we haven’t come up with something more compelling than driving a car. It’s time to get creative about this problem and take cars off the road. The suburbs are here to stay, but the cars don’t have to be.

Putting a band-aid on an infected wound doesn’t make the infection go away.

Explanation of Fields in the SMARRT form submission

Reference Scenario Inputs:

Number of People Infected – How many potential members of the gathering are infectious. The simulation starts when they enter (time=0).

Type of Activity – Impacts the number of particles spread as aerosols per respiration. More strenuous activities result in more viroid particles being released.

Air Changes per Hour – This is the air exchange rate with fresh air for the volume of air being breathed by the gathering. If you use forced air exchange, you can calculate the number of air changes per hour for your specific situation.

Space Floor Area and Ceiling Height – These are used to calculate the total space volume.

Duration Infectious Person is Present – This is how long the infectious person stays in the space after their initial entry. For the reference scenario, this defines the end of the simulation.

Gathering Scenario Inputs:

See the reference scenario for all inputs up to Time of space entry.

Time of space entry and exit – These values represent when you enter and leave the space referenced to the infectious person. For example, if you show up fifteen minutes late, but stay an hour after the end of a one hour party, the Duration Infectious Person is Present is 60 minutes, the Time of Space Entry 15 minutes, and the Time of Space Exit 120 minutes