ACCESSIBILITY OF NEW YORK CITY'S WATERFRONT
// a spatial comparison of accessibility matrices of new york city's waterfront
This study analyzes the accessibility of New York City's waterfront. Walk Score, which accesses the walkability of an area, and Transit Score, which evaluates transit accessibility, were found to be the current standards in measuring accessibility throughout the country. This study uses the results of Walk Score and Transit Score ratings along the New York City waterfront as jumping off points for evaluating waterfront accessibility. In order to create a more refined and detailed analysis of waterfront accessibility, a new accessibility rating system was created for this project that combines both walkability and transit access.
The study area for this project was limited to the waterfront of Manhattan and parts of Brooklyn, Queens, and the Bronx as to keep the study area to roughly 300 randomized data points along a 1/4 mile buffer of the waterfront. These points were then used to collect walk score and transit data. The maps below depict predictive surface models of the collected point data
// walk score and transit score
Walk Score and Transit Score are the most commonly used technology today to measure accessibility. Both of these accessibility matrixes were created by the Walk Score Company, and measure walkability and public transit accessibility. They use a scaled point system of 0 to 100. The goal of the Walk Score is to measure walkability. Points are awarded based on the distance to various amenities using euclidean distance, which does not account for the road network.
Transit score sums the usefulness of public transportation for any given point in a city. The usefulness is calculated by the distance to the nearest route stop, the frequency of the route, and type of route. Heavy and light rail is weighted the highest, followed by ferries and cable cars, and finally buses are weighted the lowest. Similar to Walk Score, Transit Score is conducted on a country-wide scale, which leads to higher overall scores within cities with larger transit networks. Transit Score does not take into account price of transit, hours in operation, and the speed, which are often major factors when considering transit accessibility. The map below of Transit Score ratings highlight that very few areas of the waterfront are lacking public transit options.
// a new index for amenities and transit ratings
As shown above, the majority of the New York City waterfront received high rating in both walkability and transit access according to Walk Score and Transit Score. However, this is based on a nation-wide scale, rather than a local one. In order to create a more comprehensive assessment of both walkability and transit access, a new index was created for this project to analyze both access to amenities and transit.
For the purpose of this study, only recreation-based facilities were used for the amenities rating. Since this study is focused on accessibility to the waterfront, in many cases waterfront parks, facilities such as doctor’s offices, banks, and parking garages were not deemed a necessary attraction for people travelling to the waterfront. Instead, the matrix was focused on identifying opportunities for dining, shopping and recreating only. Each amenity was given equal weight, but weighted more highly based on proximity to the waterfront.
For the new rating system for transit access, the best ratings were scored the lowest and were then converted into inverse percentages for the final transit rating. Subways were rated the highest since they are the fastest and often the most frequent mode for travel within New York York. Unlike Transit Score, buses were ranked next, as they are a reliable form of transportation used by many urban residents. Commuter rail and ferries were ranked the lowest in this system because of their high price and infrequent headways. Each mode was also weighted by distance to the waterfront data point. The scores for both the amenities and transit access were normalized to create a localized, New York City specific rating system.
// accessibility rating
In order to create an accessibility score for the waterfront, the transit matrix scores were combined with the amenities matrix scores, weighting them each at 50 percent. A predictive surface model for the entire waterfront area based on the accessibility scores of the coordinate points.
This new accessibility index highlights the urban scale, something that Walk Score and Transit Score neglect in their methodology. The accessibility index rates each point along the waterfront in relation to all other points along the waterfront and identifies hubs of accessibility, as well as areas lacking in nearby transit and amenities. The transit rating system is significantly more comprehensive and detailed than Transit Score, because it takes into account speed, price, and hours of operation. The amenities rating system is tailored to recreational facilities and uses a pedestrian-friendly street network, something Walk Score has not yet been able to implement.
// methodology
Due to the limitations of Walk Score and Transit Score, these existing methods of assessing accessibility were not deemed sufficient for evaluating the accessibility of New York City at its urban scale. As such, for this study we wanted to see if we can improve upon this scoring system and create a single rating that reflects the accessibility along the waterfront at the urban scale.In order to answer this research question, we developed the following methodology.
First, the study area was selected, which comprised of a quarter mile buffer area around the waterfront; roughly 300 coordinate data points were chosen within this buffer zone. Next Walk Score and Transit Score data was gathered for the waterfront coordinate points. This data was queried from the Walk Score API. Using Google Maps API, the points were reverse geocoded in order to complete the Walk Score API query. This data was then symbolized using a predictive surface model.
For the amenity and transit ratings, transportation and amenity data was collected from various sources. The location of amenities was collected from the Google Places API and the NYC Department of Parks and Recreation. Each amenity was weighted equally. The transit data was collected from various transit agencies; the data included frequency, hours of operation or speed, and price for each mode. Each transit line was then weighted based on these criteria. Each mode was also weighted, with subways being given the highest weight, followed by busses, and lastly ferries and light rail.
The network analyst tool in ArcGIS was used to create 3, 5, and 10 minute walking distance boundaries using the pedestrian-friendly street network. The rated transit stop data and amenities were then spatially joined to the walking distance boundaries. These were then weighted based on distance to the coordinate points, with a 3 minute walk being weighted the highest, followed by a 5 minute walk, and 10 minute walk weighted the lowest. The scores for each coordinate point were summed and normalized for a score from 0 to 100.
To create an overall accessibility score for the New York City waterfront, the transit ratings and the amenities ratings were evenly weighted at 50% each. The score for each coordinate points were then added together to create the accessibility index. Predictive surface models were created for each of the rating systems in order to show accessibility levels along the entire study area.
This project is only one portion of a larger collaborative study that also includes a similar analysis of the Chicago waterfront. The other group member was Kellie Radnis.
Sources: Walk Score API, Google Maps Reverse Geocoding API, Google Places API, MTA, New York Waterway and East River Ferry, New York Water Taxi, Seastreak, NYC DOT, Liberty Landing Ferry, NJ Transit, Port Authority, NYC DCP, NYC Department of Parks and Recreation
download the full project report here.