Last week I discussed transport technology designed for use on demand. Freeways, roads, bike lanes, sidewalks and stairs. We’ve noted that these technologies are not enough on there own. Freeways and roads have capacity issues when cities grow past a certain density or area. Pedestrian infrastructure is good for shorter trips, but leaves users exposed to the elements and is mostly accessible to the fit. These shortcomings can be overcome in part with mass transit. Bus and rail infrastructure can provide faster higher capacity connections than biking, walking or driving.

Buses. Buses are the cheapest and most flexible of the mass transit options. Buses can be quickly purchased and making a stop is as simple as putting in a little pole. If demand grows, more buses can be run. If a route turns out to have low ridership, those buses can always be moved to a different route. Buses also have some serious downsides. In low demand places, they can come so infrequently they become unusable. In high demand places they can get stuck in traffic. This is a catch 22 because congestion and demand for buses often grow together. Popular routes are further slowed by boarding and deboarding through the narrow doors. And all it takes is one rider with payment problems to hold up a whole bus of 60 people.

To solve the shortcomings of buses in places of high demand, there is something called BRT, or Bus Rapid Transit. BRT is a loose amalgamation of things which can be done to speed a bus route. Buses can be given exclusive lanes at traffic choke points. Buses can be given signal priority at stop lights. Stops can be upgraded to be platforms that allow for quicker level boarding and deboarding. Fare machines can be provided at the platforms to allow for offboard payment. Since these investments can be made in increments as demand warrants, buses can be a great option in constrain budgets or where demand doesn’t warrant more expensive solutions.

For the heavy lifting we have rail. Rail was a major part Puget Sound’s early transportation system, but waned with highway expansion in early 1900s.[1] The last of the streetcars were removed in 1940. When those initial rail lines were put in, rail was the only viable transport technology. Once car tech matured, it won out over rail in the large sparsely populated Sound. Now, as the region grows denser, rail based technology is making a comeback. Modern rail comes in a variety of flavors, from high speed rail, moving at 170mph between cities, all the way down to little cute street cars, slowly ambling along between cars and pedestrians.

On the low capacity side of rail, is streetcar. Street cars are often stuck in traffic. They tend to have similar capacity as articulated or double decker buses, but street cars are significantly more expensive. The advantages of street car are in style an comfort. Street cars are quiet, zero immission,give a smooth ride, and have been shown to attract higher ridership than buses for the exact same route. Installation of street car has been part of many urban revitalization efforts. While they are nicer than buses, that comes at a steep price When trying to serve the general population as well as possible, spending big on luxury should be questioned.

The heavy lifters of city transit is light rail and subway. Light rail tends to feature street level tracks, completely separate from the cars. At intersections, the signals change and gates go down so trains don’t stop for lights. Cars tend to be low floor allowing for small station platforms. Light rail is a cheaper way of getting most of the capacity and reliability of heavy rail. Light rail is often a good option if there is a wide continuous ROW with enough demand to overwhelm a bus solution.

In very dense city, there is high demand, but little room on the street. That is where subway and elevated shine. These are very costly, but are very reliable and have the highest capacity of city transit options.

Modern cities often have far sparse suburbs and good heavy rail ROW from more industrial past. Commuter rail takes advantage of this. Train cars are often double tall. Stations are often fed from large park & rides. Because commuting is one way in the morning and the other in the afternoon, trains often run empty without stopping when going contra-peak. Commuter rail tends to be costly per rider, but only medium cost per passenger mile. Commuter rail may be a questionable way to plan a city, but it can be an effective way to manage a traffic in a commute oriented city.

High speed rail is one of the most impressive forms of rail. It does best over long distance where the train has room to get up to speed without stopping. Well implemented high speed rail is faster than car and, when factoring time to get through the airport, as fast as flying. Building high speed rail is very expensive, involving lots of elevated track and tunneling, but it has the ability to shift significant amount of traffic off roads and out of the air.

The many transit option each have their own properties and costs. They often can work best in combination with other types. Subway can get sufficient ridership by being fed by buses. Buses are more useful if they connect to the faster subway. High speed rail is generally successful in places which have an extensive transit system to feed the high speed rail stations at each city. But it is also critical to use the right tool for the job. Using rail where buses would do can starve other parts of the city of transit funding. Using buses where demand is too high can cause over crowding and bunching. If light rail extends goes for too long, the time to traverse the line will be too long to be useful.

Using the best tool for the job is nice in theory, but there is also a political side to any transit investment. From complex funding plans down to local voter preference, it’s necessary to have cohesive political consensus, the topic of my next post.

 

So Seattle’s economy is hot and people are moving in as fast as they can. The traffic is going from bad to worse, but we also have money, and we would like to use that to make things better. One important question is what can our money buy. Even for a rich city, funds are limited, and we want to get the most for our money. And even with plenty of cash, right of way (ROW) is limited, so we need to prioritize the best use of the our limited space. These next two articles are a brief overview of the pluses and minuses of some of the exciting technology we have at our disposal. This article I’ll focus on personal transportation options. Next article I’ll discuss mass transit.

Freeways are relatively cheap where land is plentiful and people are few. When a freeway is freeflowing, speeds are good and you have a car where you get off, so there are no issues with mobility to and from the freeway. The two problems with freeway are one, they are spatially large, and two, they don’t really work with high traffic volumes. An example of a city which has taken freeways and roads to their limit is LA. The city is mostly flat, spacious, and implemented extensive wide freeways early in it’s development. Despite having great wide ROW and many well built freeways, LA has the worst congestion in the US.[2][3] Freeways are a great tool, but they can’t scale to handle traffic of large or dense cities.

Freeway in Puget Sound is probably not a good option going forward. The regions densest part, Downtown Seattle, is on a geographic pinch point. Hills, large bodies of water, and thin existing ROW make investing in more freeway in costly and of limited benefit. An example of a freeway style investment is the Alaskan way viaduct replacement. Seattle is trying to build a tunnel from SoDo to South Lake Union. It will be two miles, have two lanes in each direction, and was initially estimated to carry 57k vehicles (with tolls).[page442] The initial cost estimates of this relatively small section of freeway was two billion dollars[5]. It now looks like the tunnel will be significantly over budget.[4] With the size of the Puget Sound and it’s growing density, even a proper freeway system would be be congested. With our constrained freeway system and large costs for even moderate expansions, we should be judicious about further investments.

Another thing to consider with freeway expansions is the affect it will have on streets and roads. Freeways are fed by the streets and roads. Seattle has limited street capacity. To give an extreme example of our roads inability to serve our current freeways, Mercer. It was recently redone for $190 million.[6] Despite it being ten lanes wide with three through lanes in each direction, the one and only time I drove the one mile from the far side of Seattle center to I5, it took me 45 minutes. With no way of expanding the capacity of the majority of Seattle’s streets, freeway expansion can do little.

Now lets briefly talk about that contentious little vehicle, the bicycle. From an infrastructure perspective, bikes have a lot of advantages. They’re small, light on roads, and take minimal space to park. The problem is building bicycle infrastructure which is safe and gets use is tricky. Sometimes cheap minor changes become well used bicycle facilities. When Dexter was rebuilt in 2011 for $2.8 million, they used bike friendly design, including $250 thousand for bus islands. By 2013 it’s usage at peak was 300 bike per hour.[7] Contrast that with the protected bike lanes on Capitol hill. These lanes where installed at the same time as the new street car track so cyclist wouldn’t get caught in the tracks. The cost of the lane was included in the cost of the streetcar. The bicycle infrastructure is extensive, including special signalization for the bikes and full curb or parking separating bikes from motor vehicle traffic. There is a large amount of destinations along the route.[8]  In spite of the prime location and best practice design, the route has conspicuously little bike traffic. I could speculate on why Dexter succeeded and Broadway failed. But the question is, can our transportation departments make bike infrastructure which people actually use to get around. Since bikes are compact, good for peoples health, and good for the environment, infrastructure should be made with them in mind. That being said, they cannot be counted on to provide more than a transportation niche in our current infrastructure and cultural reality.

Another aspect of transportation infrastructure is walking. As a city grows denser, there tends to be more destinations in walking distance. Unfortunately walking can be made miserable if the streets are setup wrong. There are many ways to improve this. Corners can be made bulge out, so crossing the street at the corner involves less distance. Short walk paths can connect two close streets which don’t go through in cities initially built with no grid. There are many busy streets which currently have no sidewalk or sidewalk only on one side.[9] While our region has some exemplary pedestrian infrastructure, for example, Seattle has many staircases where the hills are too steep for street, there is huge room for improvement. As the region grows denser, walking becomes more important. Building and improving walking infrastructure is a cheap way to improve mobility and safety in a dense city.

What walking, cycling, and driving have in common is personal independence to use the infrastructure when needed. There is no marginal cost to run these facilities. Costs are almost entirely fixed investments. Despite the upsides of independence and fixed cost, these transport options have major downsides which can only be addressed through mass transport. Walking and cycling have the downside of being something only accessible to those who are fit and can show up wet or dirty. Cars have the fatal flaw of not scaling with growth. To address the need for high volume comfortable transportation, we need to go to mass transit, to be discussed in next weeks installment.

 

Urban layout has vast consequences for mobility. Everything from density, street layout, street design, the size of the urban area, building setbacks, parking requirements, to transit systems effects how we get around. To complicate things, all these factors not only effect mobility, but they effect the mobility caused by the other factors. To complicate yet further, all these factors have additional consideration on top of mobility. This makes considering a large transit investment something which absolutely must be done in the context of all the other factors.

 

The way I define the utility of mobility is by origin destination pairs for a given cost, be that cost time or money. One of the biggest goals of urban design, transit, cars, etc, is to increase mobility, i.e. increase the origin destination pairs over cost.

 

One of the simpler factors in mobility is simply the size of the urban area. All other urban design factors held still, a bigger urban area can increase mobility by offering additional origin destination pairs at the fringes. It can also reduce mobility by causing congestion, increasing the cost of going between the pairs in the smaller area. The larger size can also mean that transport infrastructure necessary to handle the increased congestion has to be larger, resulting in larger cost. A larger urban area can also have adverse effects on air quality and access to nature. This is important because investing in transport infrastructure which enables larger urban areas may or may not increase mobility, but will likely have other bad impacts.

 

Another of the more straightforward factors is density. Increase in density increases pair density. This can also create congestion which dilutes the mobility increase. Infrastructure to handle the increased traffic is often more expensive due to increased cost of acquiring land or tunneling to not disrupt current uses. Increased density tends to have relatively little impact on nature, but can worse air quality just like larger urban area.

 

Street layout  can be thought of by the extremes, a grid or medium size streets vs cul de sacs off of curvy arterials. A grid provides a direct relatively short linear path to a large amount of origin destination pairs. Cul de sacs mean many pairings which are geographically close are far in distance by the road. Grids evenly distribute traffic across the road system. Cul de sacs funnel the traffic onto a few major roads, heavy with the traffic for everyone must pass the same road. The pluses of the grid is it increases mobility, especially for pedestrians. The paths are shorter and the quiet streets are easy to pick for walking. For cars the increase in mobility from a grid is less clear. Cars also need to travel longer distances, but they may be able to travel at faster speeds if they are on a road designed for primarily for speed. Cars are slowed by every intersection, and cul de sacs have less signaled intersections, but few curvy arterials tend to make for huge intersections with many complicated light cycles which can take much longer all at once. The primary reason to design urban areas as cul de sacs is to make it so little traffic passes by the majority of buildings. If we work with the assumptions that all residents have cars and that the city isn’t big enough for that to make serious congestion, than cul de sacs can be used with little impact on mobility. But if residents may have otherwise not had a car, or the city grows to the size where congestion from everyone driving causes major congestion, then cul de sacs come at the a high time and fiscal cost to the residents.

 

Another important aspect of mobility is infrastructure designed for increasing mobility. Counter intuitively, it can often decrease mobility. A large road or a passenger rail line can significantly increase mobility in the direction of the infrastructure, but mobility crossing the infrastructure can be greatly inhibited. On the extreme, freeways can block crossing for miles. For someone on foot, that effectively halves the destinations reachable from places right against the freeway. Car infrastructure can even only have minimal impact on increasing car mobility. Because the marginal monetary cost to a driver of using a particular road is none, if there is significant demand for a road, congestion increases till the time cost mitigates demand. An increase in road capacity can create only a small decrease in congestion if the travel demand is flexible. Whenever considering investing in infrastructure, we must not only compare the increase in mobility with the fiscal cost, but also with the loss of mobility caused by implementation.

 

Mass transit can also improve mobility. For trips were car is not an option, transit is often faster than walking. In congested cities, if the transit has its own right of way (ROW), such as subway tunnel or bus lanes, mass transit can be faster than driving. High speed rail improve intercity mobility by being faster than driving. Sometimes transit increases mobility for only a small number of people. If the demand for busses isn’t high enough for the buss to come frequently, the wait to get on the buss can reduce utility till only people with no other options will take it. Sometimes, a small increase in demand can cause a large increase in frequency because the time cost of using the bus goes down. Mass transit can improve mobility, but only if there is enough demand and proper infrastructure is in place for the public transit to be time competitive with other options.
Things start getting really complicated when considering how all these factors effect each other. How will allowing an increase in density effect mobility. Maybe it will decrease the mobility by increasing congestion. But maybe it will increase mobility by increasing demand enough to justify more effective public transit. But what if the streets aren’t in a grid, because they were made when density was lower, the density may not allow for the increase in transit because transit requires walking and non-grid layouts reduce walking mobility. Etc, etc. No part of the system can be considered in isolation. This quick list of factors is merely a starting point for thought, investigation and considerations on how we can get to as many places as possible.

If you ever end up on I5 in Seattle during the day, a problem is immediately apparent, the transport infrastructure is comically undersized for the demand. There is simply too many people trying to use infrastructure built for a smaller population. It’s only getting worse. Between 2010 and 2015, the central Puget Sound Region grew by 207,778, 5.6%, King County grew by 121,551, 6.3%, and Seattle grew by 53,740, 8.8%.[1] Most people have tricks to manage the traffic. Many simply do their best to avoid the congestion time places, something becoming harder as the economy heats. Some people discover special alternative routes. My personal favorite trick is to take the 5 till 80th St NE, park on the first side street, pull my bicycle out of the back, and lane split into downtown. Most everyone agrees we should invest in transport infrastructure.

Some of the recent investments have been in motor vehicle transport, such as the Alaskan Viaduct replacement and the 520 bridge rebuild. Other investments have been in public transit such as Sound Transit 2 (ST2), which is building light rail from downtown Seattle north to Lynnwood and East through Bellevue. The first leg of ST2, a tunnel from Westlake station to Capital Hill then UW, has just opened to higher than projected usage.[2] Even with these large investments, it is not enough.

Sound Transit is now preparing Sound Transit 3 (ST3), a 25 year 50 billion package which would add rail north to Everett, south to Tacoma, from Ballard to West Seattle, and from Redmond to Issaquah. In November, ST3 will go to a vote in the sound transit tax district. As a voter I would like to be informed. Can Sound Transit deliver what they promise? Is this worth the cost? Could we do something better with the money? To answer these questions, we need to 1. look at mobility in a holistic fashion, 2. evaluate our technological options, 3. understand what our political structure allows us to do, and 4. consider our options in the context of our voter culture and our technical and political realities.

Mobility in general is what we really want. Another way to look at mobility is how many destinations of what importance and at what cost can be reached. There are many ways to improve mobility. Mobility for an individual can be improved by buying a car, thereby reducing the time and effort to reach distant destinations. Mobility can be improved by building high speed rail so people can get to different stations quicker. But mobility can also be improved by making a city denser, so there are more destinations in the same distance. But many of these things can reduce mobility as well. Too many cars can make it so buses can’t get through. Trains or freeways can block the path between adjacent origin destination pairs. Denser city can mean more congestion, so despite more destinations in a given distance, the time to travel that distance can go higher. Because every change makes things both better and worse, it is necessary, when optimizing mobility, we think of the system as a whole.

Once we have a theoretical idea of how we want to move our system, we need to consider what technological options do we have. What sorts of transportation tool do we have at our disposal. These can be anything from small, such as bus queue jumps, to mega projects such as tunneling rail under downtown. Some of our most important options are tools such as zoning.

Even when we know how mobility works and what options we have at our disposal to increase it, implementing these mobility increases is a fraught political process. Our political structure is complex and any improvements will need to reflect that.

Once the political process has generated possible improvements, we need to ask, is it worth it? Would it be better to shoot this down and wait for something better or would we be would be simply delaying critical transportation improvements.

These are the issues I hope to address in my four following posts. Mobility, technology, political structure, and voter value. A solid grounding in those topics will leave us well suited to make decisions on the future of our infrastructure, including ST3.