Rationales for Where to Change Streets

Introduction

Team Where’s Senior Capstone Project [Spring Semester 2021] investigates myriad factors to influence where changes to urban streets would likely have the strongest opportunity for readiness. Using Denver City/County, Colorado as the example for our proof-of-concept project, we uncover factors and identify specific segments of streets in urban neighborhoods that could lead to impactful improvements. We employ criteria and data to produce a model, or a “proof-of-concept”, to test drive a new approach for locating street segments that may be met with the most success when introducing/implementing various positive improvements. As a group, we look at how future development is selected and address new ways of thinking for short or long term street changes. From our project, a framework has been developed that determines the best locations for innovative change and design in urban streets.

• Create a template that can be applied to any city - starting with Denver, CO, as the example location.

• Propose a new model of criteria for selecting streets best suited for change and a proof-of-concept to address the new ways of thinking on changes in city streets.

The Team Where project considers multiple outside theories from planning and transportation industry professionals, some of which were guest speakers in the course, and multiple data sources.

Relevance

While there are planning practices and engineering guides for street changes, there are not universal guides for determining where changes should happen. Different models identify ‘what’ redesign(s) could entail, and there are case studies that determine ‘how’ changes might be implemented (through design or policy / through permanent or temporary changes), but the model for ‘where’ is currently non-existent.

One of the primary obstacles regarding street change is that change cannot occur anywhere and/or at any time, even when necessary. That is why Team Where seeks to provide a prioritization scheme - ‘an all-encompassing guide to where.’ We stress the highest opportunity for change, help the ease of implementation, and accelerate the historically slow process for change and innovation. Towards this end, we provide: (1) a rationale for our proposed process, (2) a ranking system to categorize available data and criteria, and (3) visual representation(s) for our findings that display the ‘best’ streets for change in Denver specifically.

Overview

Phase #1: Brainstorm a list of criteria that would highlight opportunities for change. Find/collect open-source data on these criteria from various sources and start filtering it into GIS software.

Phase #2: Create a ranking system from our list of criteria. Organize the data and determine what information is relevant to our core project.

Phase #3: Produce written and visual representations of our criteria, ranking system, and proposed locations. Insert final product into the class website along with tertiary information that supports our project’s argument.

Initial Findings

Street Ownership

One of the first steps in the process of modifying existing city streets is receiving permission from the individual/entity that owns the street. The type of owner (City, County, State, Federal Government, or Private) can determine how complicated and time-consuming the process will be.

The concept of street ownership was first brought to our attention by Tila, when she stated that city-owned streets typically have the quickest overall process times because of the current nature of the street change process. Through open access data, we found that the City and County own the majority (82.59%) of street segments in Denver. This information aided the decision to highly prioritize city-owned streets in the ranking system.

Street Type

Local Roads are highly prioritized within the ranking system. Generally, they have a workable volume of traffic, lower speed limits, and are more manageable when implementing change.

• Arterials: Major, high-capacity urban roads that usually carry large volumes of traffic. Arterials are often divided into major and minor arterials and rural and urban arterials.

• Collectors: Traffic from local roads. Distributes traffic volume to arterials. Traffic using collector roads is usually going to or coming from somewhere nearby.

• Local Roads: Local streets/roads have the lowest speed limits and carry low volumes of traffic. In some areas, these roads may even be unpaved.

Gaps in Existing Transportation Networks

Incorporating the gaps in existing transportation networks in our framework was a concern. However, this layer of information is not readily available through open-source data and is challenging to create from scratch. Although we could not successfully identify gaps in existing transportation networks to use as a criteria, we still recognize the value of this information and hope that it will become available for use in the future.

Having complete transportation networks, particularly for pedestrians and cyclists, is fundamental to the future of cities and streets. These gaps significantly impact peoples’ ability to travel from origin to destination. Collecting feedback through surveys on this issue, and others, would be a valuable step towards creating a more complete, safe, and equitable networks in cities.

Public Support

In Denver, locals can start petitions to enact changes in the streets, but all petitions have to go through the City Engineer. For example, the petition submitted to the Mayor’s office with more than 1,000 supporters (started by members of the Denver Bicycle Lobby) hopes to keep the Shared Streets Program changes [Reddit Thread]. Aside from petitions, online public forums also show upcoming projects and requests from the public advocating for change. This informed us that social media is a platform for community engagement for what is happening on the streets, and accessing locals' opinions/input matters.

Denver Residents Push To Make Shared Streets Permanent

Maintenance Requests

It is easier to implement change to streets that are already undergoing maintenance. Tila suggested cross-referencing maintenance requests with current maintenance schedules to produce high-priority locations. However, we could not find a consolidated maintenance schedule for Denver (typically set at the beginning of each year). Eulis Eckley [the Director of Denver...], suggested looking into Denver's Pavement Plan. This information was located within our initial data collection, but we were unable to insert it into GIS because the associated data is not attached [the plans are already in Map Form]. Although, we were able to slightly work around this lack of information because we were able to identify a few street locations associated with Local Maintenance Districts [see image below]. Maintenance Districts form when a group of neighborhoods and businesses want to upgrade the streetscape with special features such as pedestrian lights, benches, or vegetation landscaping. For the future, it would be helpful to have annual maintenance schedules publicly available.

Blueprint Future Mobility

The Future Mobility section of the Blueprint Denver Plan (2019) highlights modal priority types for new transportation segments across the City and County of Denver. The plan, adopted by the Denver City Council, shows where there are existing plans in Denver for new growth, transportation, and design. We incorporated this plan to recognize existing city projects when suggesting new street proposal locations.

Crash Data

Crash data is a crucial component of our prioritization scheme. Deciding where safety improvements on city streets should be implemented could literally save lives. Crash data can inform many decisions and significantly affect the final product. For example, fatal vehicle crashes involving pedestrians and cyclists rank the highest on our priority scale.

The map below shows crashes resulting in fatalities and seriously injured pedestrians and bicyclists in 2019. There were 75 fatalities and 451 seriously injured due to vehicle crashes. It is important to know that the data had many values currently under investigation [or zero], so the counts might be higher than what is currently represented.

Annual Average Daily Traffic (AADT) Counts

AADT counts throughout the city help identify which streets have relatively high, medium, and low traffic volumes. Changing streets that have high traffic volumes requires more time and money and has more pushback (because the finished product and construction process affects more people). However, changes to low traffic volume streets risks not seeing enough usage. Therefore, this project highly prioritized street segments in Denver with medium AADT counts.

Precedents

Two precedent projects used a criteria prioritization scheme to determine the best locations to introduce city street changes, similar to ours. The first, in Quebec City, used a multi-criteria approach for new bicycle infrastructure. The second, in Denver, used a strategy to reduce crowding in parks and streets.

1. The Quebec City Study used a multi-criteria approach, selecting the best areas for implementing new bicycle infrastructure. Seven different criteria were assigned weights and then used to map potential locations. Since this study focused only on bicycling, the framework cannot be applied to different modes or general street improvements. However, the authors used the resulting locations to model and predict which streets would see enough use to justify the installation of infrastructure, which could be an area where our project is taken further.

2. Jay Decker from the City of Denver, demonstrated an approach to reduce crowding in parks and streets in the wake of COVID-19 lockdowns and restrictions. Denver created Temporary Recreation Streets (T-RECS) for safe and socially distanced recreation. Decker and his department calculated the best locations for T-RECS by considering criteria such as adjacency/distance from parks, street typology, public transportation presence, qualitative staff knowledge, zoning, and intersections with collector and arterial streets. Two scenarios were produced, prioritizing residential density and equity, and using GIS to visualize.

The Team Where project framework is unique because it can essentially apply to any city to make recommendations for any type of desired street change. Even though a few precedents have used similar methodology, they were designed for a given location with a specific goal in mind. Additionally, our framework allows users to customize results by assigning different weights to different criteria, effectively prioritizing specific needs over other factors.

Ranking System

The categorical ranking system groups our criteria based on their importance. Each of the criteria are given a high, medium, or low priority grouping. High priority criteria are 9 to 7, medium priority criteria are 6 to 4, and low priority criteria are 3 to 1. The importance of the criteria is measured by impact and feasibility, mixed with an overarching mind frame for each scenario.

Three goals for our ranking system:

• Assess where street locations would be most accessible or most impactful to change and why (e.g., those owned locally, those undergoing maintenance, accident reports, those where residents are requesting change).

• Produce a model or a “proof-of-concept” using a categorical ranking system that helps to redefine our predetermined set of criteria.

• Determine new street locations best suited for change based on data collected from sources such as the City of Denver, ADDT, RTD, and Census Data.

The primary purpose is to determine how easy, quick, and practical it is to identify change areas and implement change with the highest priority scores indicating where intervention/change could likely succeed. For example, street type and speed limit are high priority when determining the location for new street changes. A medium priority includes streets with existing RTD stations and bike lanes.

High Priority: 7-9

• Street Type/Speed Limit

• Ownership

• Crashes: Involving pedestrian and bicycles

• AADT

• Public Requests (for maintenance or new infrastructure like speed control)

• Population Totals

• Population in Dependent Age Groups (under 18 and 65+)

• Denver’s Equity Index (Overall Equity Per Neighborhood)

• Communities of Color

• Fatalities from Crashes

• Asthma Projections

• Parks and Vegetation

• Speed Limits

• Maintenance Request

Medium Priority: 4-6

• RTD Routes

• Bike Lanes

• Zoning

• High pedestrian traffic

• Commute to work: walking and bicycling

• Household Income per Year

• Blueprint Modal Priority

• Floods

Low Priority: 1-3

• Car crashes

• Parks and Vegetation

The criteria not applied, but still contains data attached to other criteria, has a zero ranking. [example: freeways/expressways = 0]. The ranking numbers are multiplied together for every street segment in the city. Streets with the highest comparable scores are indicating where intervention/change could be most successful.

A significant challenge when creating a non-established ranking system is that all decision-making processes are up to the creator. It is difficult to place a value on multiple criteria without fully understanding the unintended outcomes or the current systems in place. Some of the rankings are personal decisions guided by outside planning concepts and sources that depend on past education and individual experiences. The challenge is to make sure the framework for this project is rated impartially.

INCORPORATING SAFETY FOR FUTURE STREETS

Safety Scenario

"Framing street changes around safety will harbor the most success." - Jessica Vargas

Better pedestrian safety outcomes are essential for future streets, and it is the responsibility of planners to work towards better safety goals. Projects such as Complete Streets and Vision Zero work to reduce and optimally eliminate all pedestrian fatalities.

Vision Zero Denver Streets Partnership (an initiative that seeks to eliminate pedestrian traffic deaths) already works to "reclaim Denver's streets for people walking, rolling, biking, and using transit, and to build safe, healthy, and equitable communities." While planning decisions differ, advocates for Vision Zero might propose traffic-calming measures for increasing safety as "the most dangerous streets require the most attention" (Jessica Vargas). We want to represent safety for future street changes by allowing "human-centered policies to guide the design of our city, streets, and public spaces."

Incorporating safety helps address the most ‘at risk’ streets when looking at population-based pedestrian fatalities and pedestrian and cycling crashes, and ultimately minimize them. High Priority factors included in the Safety Scenario are Street Type, Street Ownership, AADT, Bike, and Pedestrian Crashes, Fatalities, Communities of Color, Income, and Speed Limits are rated high priority. Blue Modal Priority is ranked a medium priority, and Car Crashes are ranked a low priority.

The Safety Rating Framework uses Natural Breaks to identify the best distributions of data. The map also shows limited streets with the highest class because of the natural breaks system. Varying frequencies of observations per class were used for all maps. Zero was manually entered for all Null values [Example: roads that can’t be altered because they are non-city-owned].

Crashes

The ‘traffic crash data’ is from Denver Open-Data and edited to follow 2019 crashes due to the large dataset size and to avoid decreased vehicle volumes from the global pandemic.

Fatalities include any death from a collision - including pedestrian, bicyclist, vehicle driver, or passenger.

EQUITY CONSIDERATIONS FOR FUTURE STREETS

Equity Scenario

“Inequities in existing transportation networks negatively impact traditionally disadvantaged communities (communities of color, lower income communities, etc.).” - Chuck Brock

Equity should be an integral part of all planning considerations. The creation and perpetuation of racial inequities are embedded into government at all levels (Boulder's Racial Equity Plan). Focusing on equity provides the opportunity to introduce a framework that applies future street changes to marginalized groups or where populations are most vulnerable.

Guest speaker Chuck Brock emphasized strengthening existing transportation networks in low-income communities. A research study by CDOT concluded that "providing reasonable travel options such as convenient public transportation and safe pedestrian facilities to individuals who do not own vehicles is a critical factor for low income and minority individuals to access jobs and to participate in the same quality of life as the general population." Many communities lack proper access to transportation networks that provide multiple options and various modes to address social and economic equity. "The relative lack of public transportation in many parts of Colorado places a high burden on low-income individuals, including the inability to access essential life services without access to a car and a high percentage of income allocated to transportation costs" (CDOT, 2006).

The Equity Scenario identifies inequities in different neighborhoods and proposes locations best suited for change based on streets most vulnerable. It further provides a template for where streets should consider better transportation networks. High Priority factors within the Equity Scenario are Denver's Inequity Index, household income levels, race demographics, population totals, and population groups under 18 and over 65. Other factors include street type, street ownership, commuting to work (walking and biking), zoning, and maintenance requests. Most of the data used in this scenario are from the Census Data, ASC Census Tract data, or Denver County Government Open Source data. These are only a few considerations when thinking about equity. Other variables can help strengthen the framework depending on the project. Additional factors might include food insecurity, gender, disabilities, or access to infrastructure.

Denver’s Existing Equity Index

Denver’s Equity Index (2020) shows inequities in different neighborhoods based on socioeconomics, the built environment, access to health care, and health barriers that residents of Denver face in accessing opportunities. We looked at five different maps based on Denver’s Equity Index that display inequities in Denver neighborhoods.

We only incorporated the Overall Equity Rating Per Neighborhood into our ranking system due to project time and scope limitations, but acknowledge that there are limitations. Each equity index map displays different levels of specific inequity. For future projects or different scenarios, other equity index maps might be suited better.

Income Levels

Income is incorporated into our criteria, showing where income ranges differ for different neighborhoods. Our ranking system is taken from the ACS Median Household Income Variables by Tract and contains 5-year estimates for household incomes. The ranking is calculated by income levels, with the lowest incomes having the highest priority.

Income/Poverty (Census Tracts): Percent of Population Below the Poverty Line

The Percent of Population Below the Poverty Line data is not incorporated into the ranking system but helps provide a more detailed understanding of poverty levels not shown in the Household Income Per Year data. The map contains selected census tract level demographic indicators (estimates) from the 2013-2017 American Community Survey representing the population's percent (for all persons) with annual income below the federal poverty level.

Populations

The Percent of Population in Dependent Age Groups looks at population densities for people under 18 and over 65. Guest speaker David King states that since the built environment is planned around vehicles, it is not always convenient for vulnerable populations. If an older person gets off the bus to go to the shopping market, they still have to go through a large parking lot to get there. We wanted to incorporate children and the elderly as a high priority in our ranking system because they rely more on the built environment to keep them safe and use it differently than other age groups due to possible limitations when accessing urban areas.

Commute to Work (Walking or Biking)

The Commute to Work map data looks at the percentage of people who commute to work either by biking and walking. The base map is population totals in Denver County from the ACS Population tract census data for 2015-2019. This data is important to consider because people who commute by walking and biking both live and work in the same area, and it shows volumes of pedestrian activity. Guest speaker Bob Schneider reiterates that pedestrian volumes are a key factor for understanding safety.

Race Demographics

It is important to incorporate race demographics into our study, but we did not want to categorize the importance of or prioritize different races. Instead it is used as additional supporting data to ensure there are no gaps in these areas.

ENVIRONMENTAL FACTORS FOR FUTURE STREETS

Environmental Scenario

“Transportation, or mobile, emissions from trucks, trains, airplanes, and all other motor vehicles comprise the largest single contributor to Denver’s air pollution.” ~ Kampa

Guest speaker Chuck Brock identified the intersection of environmental sustainability and social sustainability as an area where transportation planning might create solutions. Guest speaker Martha Roskowski suggested increasing network connectivity by using existing infrastructure, like planters, to create protected bike lanes. Merging Chuck and Martha’s ideas, we sought to locate streets that could benefit from adding green infrastructure.

The Environmental scenario uses our framework to prioritize changes to streets that will positively impact and support sustainable street designs. It prioritizes criteria like health, floodplains, existing parks, and vegetation. This scenario might be applied after an environmental advocacy group approaches a city’s transportation department with a request to implement sustainable components into existing streets. The locations resulting from the ranking process provide what streets might benefit from introducing permeable surfaces, flood mitigation, and infrastructure to link existing parks and green spaces into the street design.

Air Quality

Guest speaker Jim Charlier proposed the importance of incorporating air quality into our environmental scenario because it directly relates to transportation. “Air pollution’s main change in the atmospheric composition is primarily due to the combustion of fossil fuels, used for the generation of energy and transportation” (Kampa, 2008). When pollutants are released into the air, they can cause adverse effects on human health and the environment.

Denver is especially susceptible to poor air quality and was once known for its “brown cloud” of smog that lingered over the city. Air quality in Denver has significantly improved since the 1980s but continues to be a problem. There are several significant air and ozone pollution sources such as power generation units, coal-fired power plants, and wildfires (Woodruff, 2019). However, transportation is the largest single contributor to Denver’s current air pollution” (IQAir, 2021).

Current Air Quality Index of Denver

Currently, Denver’s air quality is most susceptible to ozone pollution caused by pollutants emitted from motor vehicles and the oil and gas industry (Woodruff, 2019). In April 2020, Denver released a new electric vehicle action plan to promote electric vehicle ownership further and hopefully reduce mobile emission sources in the future.

“Denver residents and businesses are slowly adopting electric vehicles. However, the current and expected rates at which they are purchasing them does not put Denver on track to reach its EV goals in 2025 and 2030” (Denver Action Plan, 2020).

According to IQAir, at the beginning of 2021, Denver experienced a period of “Moderate” air quality with a US AQI reading of 56 according to recommended levels from the World Health Organization (WHO). The concentration of the PM2.5 pollutant was 14.6 µg/m³. At this level, it is recommended to close doors and windows to prevent the entry of dirty air into the home. People who are sensitive to allergies and health issues should avoid going outside until air quality improves.

While there are numerous sources for air pollution data, our group struggled to find open-source data for Denver that could be integrated with our ranking system. However, we are incorporating other health information such as asthma rates into our ranking.

Asthma

The asthma data is high priority in the ranking system and is from Denver Open Data. The data shows projected asthma levels based on census tract data. This projection is based on modeled survey data collected from Colorado Behavioral Risk Factor Surveillance System.

Proposed Street Locations

The final map includes all of the factors from the Safety, Environment, and Equity rating frameworks. The streets with the highest priority help guide us in our decision for a single final street location.

N. Tennyson St between 38th and 39th St

N. Tennyson is a collector road with an average traffic volume of 22,941 vehicles per day. There was one car-to-pedestrian crash in 2019 with no fatalities. This block is the start of a mile-long neighborhood and commercial district. It is located by Marianne Parkway and Washington Park.

Project Conclusion

• Streets are often slow to develop. Providing a formula and proof-of-concept surrounding the location selection process allows cities to input their own criteria for future street change.

• It is challenging to create a non-established ranking system where all decision-making processes are up to the creator.

• It is difficult to place a value on multiple criteria without fully understanding the unintended outcomes or the current systems in place.

• Each scenario produced completely different results depending on the criteria and ranking priority.

Innovations within the public realm are an exciting part of being an urban designer and planner, but innovation means change. Historically, the speed at which street change happens has typically been slow. In a world where change is inevitable, and innovation is necessary, Team Where hopes to build a framework that looks at short and long-term solutions to address growing concerns, problems, and societal issues.

Our framework's design is subjective since it requires users to prioritize specific criteria over others throughout the ranking system. The weight assigned to each criterion has a significant impact on the results, leading to variations in results from user to user. For example, a user who assigns a weight of 7 to population totals could find a set of results that do not overlap with a user who assigned a weight of 9 to population totals.

Therefore, we caution all users to carefully consider how they rank each of their criteria, as the weights assigned could lead to unintended outcomes. We encourage users to experiment by assigning different weights to each of the criteria and note how each resulting scenario produces different results.