Planning for Equity in Public Transit

Think about all the places that your family goes in a given week. People in your family might go to school, workplaces, grocery stores or to a doctor’s office. Your daily choices are often shaped by how long it takes to get to these places. For example, you probably don’t want to go to a grocery store that is 4 hours away from your house! Having services and stores close to your home saves you time and makes your life easier.

Public transit is one of the ways many people get to these places, especially in cities. This means that where we build public transit has big impacts on people’s lives.

For example, changing a bus route might double the amount of time it takes someone to get to work.

Planning transit based on these impacts can help us build more equitable cities.

Image - Text Version

Shown are people sitting on a public bus. In the center of the frame, a man in his mid-twenties with dark-brown skin and mid-length natural hair is sitting beside a a woman in her mid-twenties with light brown skin and long naurallly curly hair. She is wearing dark-rimmed glasses. The woman is gesturing with her hands. Both are smiling. A man in his mid-twenties with white skin and light brown hair, mustache and short beard is shown in the row of seats in front of them. A young body with pale white skin and brown hair is sitting by the window in the row behind them.

What is spatial analysis?

Planners use spatial analysis to make design decisions about cities. Spatial analysis is a way of interpreting geographic information to answer questions. Whether you know it or not, you’re doing spatial analysis every time you look at a map. For example, take a look at this map of the Toronto Subway.

Figuring out how to get from one point to another on a map is a simple form of spatial analysis. We use computers to do more complex forms of spatial analysis. Geographic information systems (GIS) connect data to a location on a computerized map. GIS helps us answer more complicated questions. For example, we can attach data from the Census or household surveys to locations. GIS allows us to then look for patterns in this data. Let’s take a look at an example of how people are using GIS to build more livable cities.

Did you know?

The first computerized GIS system was developed in Canada in the 1960’s. This system tracked natural resources and land usage.

Spatial Analysis in Action: Transit and Access to Jobs in Toronto

Being able to access jobs is an important part of a healthy city. In a big city like Toronto, Ontario, public transit is often the most affordable way of getting around. Planners at Jacobs used GIS to investigate the question:

How will new public transit lines impact the most vulnerable neighbourhoods in Toronto?

To answer this question, they needed to figure out how long it takes people to get to work. To do this, they created a grid of points covering all of Toronto.

Image - Text Version

Shown is a map of Toronto with the grid points and networks used in this analysis. The grid points are shown as small black dots. There are thousands of them around the city. The networks are show as black lines of varying thicknesses.

Next, they included a network showing the ways people get around. This included sidewalks, roads, subways and bus routes. This allowed them to calculate how long it would take for a person to travel from a grid point to any other grid point.

Let’s take a look at how they analyzed the journey from a single grid point to another grid point. If you were on that journey, it would look something like:

1. Leaving your house and walking to the sidewalk
2. Walking along the sidewalk to the bus stop
3. Getting on the bus and travelling along the road
4. Transferring to another bus and travelling along more roads
5. Getting off the bus
6. Walking along the sidewalk and into your school

The way the analysis sees that journey is:

1. Getting from the grid point on to the network
2. Travelling along the network using the shortest path
3. Getting off the network and back to another grid point.

Let’s take a look at the math behind these steps.

The first step involves moving from a grid point onto the network. This step uses the Pythagorean theorem to find the closest point on the sidewalk to your home. The Pythagorean Theorem uses the equation a² + b² = c² where a, b, c are the lengths of sides of a triangle.

Image - Text Version

Shown is an illustration of how a triangle can be used to identify the shortest distance between two points. There is a small grey line drawing of an image of a house at the top left. The house is at the topmost vertex connected to the hypotenuse of a right triangle. A road crosses through the image below the triangle. One point on the road is at the another vertex connected to the hypotenuse of the triangle. The third vertex of the triangle is beside the right angle. The triangle sides are labelled a,b, and c. Side a is the horizontal side, side b is the vertical side and side c is the diagonal side.

The next step involves travelling along the network using the shortest path. This step uses Dijkstra’s algorithm to find the shortest path of travel along the network. The algorithm is very efficient because it doesn’t look at every possible route from start to end. While it calculates the time for every possible route as it moves away from the starting point, it always keeps track of which of those possible routes is the shortest at any given time. As it moves outwards in search of the end, it prioritizes what appears to be the shortest path first and keeps moving in that direction. Once it finally reaches the end, it knows that the first (and only) possible path to do so, is the shortest path.

To do this, the algorithm adds up every part of the shortest path. This means it adds up the time to walk along the sidewalk from your home to the bus stop. Then it does the same for waiting for the bus, riding the bus and transferring to another bus. Finally it looks at the time for riding that bus, and walking along the sidewalk to your school. As it does the time calculations on the network, it moves outwards as shown in the image until it finds the destination.

The spatial analysis repeats this process many times over for each grid point to every other grid point. This means that the number of calculations  grows exponentially by the number of grid points, squared. In the analysis for the TTC, that was over 28 billion calculations (167 882² = 28 184 365 924)!

The third step again uses the Pythagorean theorem to move from the network to a grid point.

Planners at Jacob used GIS to complete these three steps for every single grid point. If the travel time from one point to another was less than 45 minutes, they counted the number of jobs and people at that end point. They analyzed this using both current and future transit options. Finally, they created a map showing how access to jobs would change for each location in Toronto with the addition of new transit.

This map shows how future transit projects could improve job access. It also highlights which neighbourhoods would benefit the most from these projects. This data was then compared with indicators of neighbourhood well-being. This allows planners to identify which neighbourhoods need transit improvements the most.

Planners used this analysis to decide where to build new transit projects. These projects will improve access to jobs for many people in Toronto. This type of spatial planning can help make cities more equitable places for all of us.

Image - Text Version

Shown is a colour photograph of a streetcar on tracks moving down the centre of a street in Toronto. The streetcar is red and white with glowing headlights on the front. It is long and rectangular-shaped. It is attached to cables which run above it down the middle of the street at about the height of a two-story building. Two and three-story buildings line the street. The CN tower is visible stretching into the sky in the background.

 Let’s Talk Science appreciates the work and contributions of Tim Dickinson and Michael Grant of Jacobs in the development of this Backgrounder.

About Jacobs

At Jacobs, we're challenging today to reinvent tomorrow by solving the world's most critical problems for thriving cities, resilient environments, mission-critical outcomes, operational advancement, scientific discovery and cutting-edge manufacturing, turning abstract ideas into realities that transform the world for good. With approximately $14 billion in revenue and a talent force of more than 55,000, Jacobs provides a full spectrum of professional services including consulting, technical, scientific and project delivery for the government and private sector.