1. Introduction

Beginning with the next version of the Geopath Insights API due in November 2021, Geopath will begin releasing transit media impressions data using new methodologies that align with our existing audited inventory.  Geopath intends to also deliver impressions data for transit media in the Geopath Insights Suite at the same time. Previously, we were delivering these metrics in the legacy OOH Plan tool.

Generally, impressions via transit can occur with advertising placed inside of transit rail stations, on bus stops, and on the inside and outside of vehicles. Each of these are measured with different methods. Inventory at bus stops are already fully measured using our roadside methodology with vehicular and pedestrian traffic in the same way a bulletin or poster are measured. These exist already in the Insights Suite and via the API.

Inventory at transit rail stations (henceforth referred to simply as transit stations) and inventory on the outside of transit vehicles (henceforth referred to as exterior fleet systems) are each detailed in this document. We are releasing impression data for 45 transit stations and an initial set of 17 exterior fleet systems. The remaining 135 fleet exterior systems will be updated on a rolling basis throughout the scheduled bi-weekly releases. Lastly, inventory on the inside of vehicles (also referred to as interior fleet systems) will be updated in full in Q3 of 2022, and its methodology will be detailed in a separate document.

With this release, ridership and general transit feed specification (GTFS) data have been refreshed for each transit system that we support. At the garage and station level, the inventory quantities and attributes were also updated by frame.

This document primarily outlines the new methodology for the transit media types to be released with this forthcoming November 2021 update. First, a general overview is given. Transit stations are explained in more detail next, and we follow this by a detail of the methods for exterior fleet systems.

2 Methodology Overview

Geopath generally uses a four-stage approach to producing impressions: traffic, circulation, opportunity-to-see, and likelihood-to-see.

Open

The methodologies presented here are similar to our existing inventory. Measurement starts with an estimate of how many vehicles or people are traveling along a roadway, on a pathway, or within an area. Using a set of adjustments, that traffic count ultimately becomes a number that reflects the likelihood-to-see an advertisement, which is impressions.

The following table outlines which approach to measurement is most closely used for each of the four types of transit media.

Generally, there are greater differences between the traffic and circulation stages of estimation. The opportunity-to-see and likelihood-to-see stages are consistent with the existing place-based and roadside methodologies.

3 Transit Stations

The 45 transit stations supported by the Geopath Insights Suite and API come from the legacy OOH Plan tool and from operator submissions to Geopath since the last update in the legacy tool.  We can add additional stations or make modifications to existing stations as needed.

In some cases, we know that inventory exist within a transit station but do not have details about the media inventory there. For these, we list one “placeholder” two-sheet unit for each station.

Methodology

Transit stations are measured following the place-based methodology. The four-stages are outlined with the following:

1. Traffic is the number of people in an area representing the transit station.

2. Circulation is the number of people in an area representing the transit station who are oriented so that the media is within their field of view.

3. Opportunity-to-see exposure is the number of times that content is displayed to and able to be seen by people in an area who are oriented so that the media is within their field of view.

4. Likelihood-to-see impressions is the number of times that content is displayed to and seen by people in an area who are oriented so that the media is within their field of view.

Traffic

The place-based methodology starts with counting foot traffic using mobile location data to estimate the number of people by hour. Each station is considered a venue which has its own average visitation attributed to it. If the station is an above ground station, we rely on the place-based approach using a drawn polygon, ridership data, and mobile location data. If a station is below ground, pedestrian or vehicular traffic can occur above. In this case, only ridership data are used towards calculating the number of people in the station.

Circulation

For inventory inside transit stations, traffic is reduced to circulation by considering field of view with each frame’s placement type. Placement type is the area within a transit station where the frame is located and can be, for example, entrance/exit, concourse, or platform. A concourse is the large open area inside or in front of a transit station, and a platform is an area alongside a railway track providing convenient access to trains.

For each placement type, a variety of sizing metrics are used to determine a “discounting factor” called placement exposure. The following table gives examples of placement exposure factors for various combinations of placement types and sizing metrics.

For each placement type, an additional “discounting factor” is used called exposure probability. The following table gives examples.

In addition to entrance/exit, concourse, and platform, these other placement types exist that have their own placement exposure and exposure probability factors: above staircase, curbside, dining area, elevator lobby, fare gate, fare machines, hallway, interior corridor, lobby, open floor, parking lot, waiting area.

Opportunity-to-See

Opportunity-to-see adjusts circulation by accounting for the number of times that content is displayed. For illuminated inventory (digital advertisements), the ad length, layout share of voice (percentage of time of ad play versus other news or service announcements), and spot share of voice (percentage of time of play of a specific ad in a loop) are considered. For static inventory, opportunity-to-see is the same as circulation.

Likelihood-to-See

A Visibility Adjustment Index (VAI) is applied to go from an opportunity-to-see exposure number to a likelihood-to-see impression number. The following components make up VAI.

Structure Type

A frame will be within a particular structure type such as interior wall, furniture, freestanding, or column. The structure type plays a role in the visibility and dwell factors associated with these attributes.

Max Noting Distance

Max noting distance represents the maximum distance an individual can be from a unit to still see it. As the size of the unit increases, so does the max noting distance. For example, an advertisement on a television screen may be viewable from 30 feet away, but as soon as the viewer is 31 feet away from a unit, the brand message is no longer distinguishable. Therefore, the max noting distance for that television screen is 30 feet. The size of a given screen will determine the distance.

Dwell

Dwell is the length of time an individual spends in the proximity of a frame. Dwell can be “passing” or “extended”, where passing refers to time in motion while in proximity to the frame. Depending on the placement type, the dwell may be entirely “passing” in which case the average walking speed is considered to determine time of exposure. For the placement type of platform, the dwell is split between “passing” and “extended”.

Engagement

There are different levels of engagement a screen can offer based upon the content provided, which factors into the quantification of possible impressions. Each of these relate to the likelihood that the screen content could induce consumer engagement.

·        Low Screen only shows ads/messaging. no content provided adjacent or between spots.

·        Mid Screen displays content that is relevant to the environment between spots (e.g., health news and tips are displayed in between ads in doctors’ offices).

·        High Ad/messaging are on screen at the same time as contextually relevant content (e.g., ads are positioned on screen alongside scores at gaming venues).

·        Highest Ad contains both audio and full motion video elements, increasing the likelihood that the ad itself is perceived either auditorily and/or visually.

Interactivity

Interactivity can include screens that, in addition to ad content, contain things like games, vending machines, or directory information. Interactivity is considered as a logical factor, meaning the frame is either interactive or it is not.

4 Exterior Fleet Systems

Impression data is published into our staging platform of the Geopath Insights Suite in Q1 of 2022.  Fleet inventory will be published into our production version in Q2.   

Methodology

Exterior fleet systems are measured using the roadside methodology. The four-stages are outlined with the following:

1. Traffic is the number of vehicles traveling along a roadway (often in either direction) and the number of people walking along a walkway in either direction.

2. Circulation is the number of people traveling in vehicles along a roadway and walking along a sidewalk or walkway in a direction where the media is within their field of view.

3. Opportunity-to-see exposure is the number of times that content is displayed to and able to be seen by people traveling in a direction where the media is within their field of view.

4. Likelihood-to-see impressions is the number of times that content is displayed to and seen by people traveling in a direction where the media is within their field of view.

The main differences between exterior fleet systems and roadside is how traffic is counted and the extended periods of dwell as transit passengers wait for and ride on transit vehicles.

Traffic

To estimate the traffic for exterior fleets systems, we start with General Transit Feed Specification (GTFS) data. The General Transit Feed Specification (GTFS) is a data specification that allows public transit agencies to publish their transit data in a format that can be consumed by a wide variety of software applications. Today, the GTFS data format is used by thousands of public transport providers.

The following tables are required for our purposes:

·        Agency The agency table provides information about the transit agency as such name, website, and contact information.

·        Stops The stops table defines the geographic locations of each stop or station in the transit system as well as, and optionally, some of the amenities associated with those stops.

·        Stop Times The stop times table shows the arrival time and departure time at a specific stop for a specific trip on a route.

·        Trips A trip is a sequence of two or more stops within a specific time.

·        Routes The routes table describes how agencies communicate their services to riders. Trips belong to one route.

·        Calendar The calendar table defines service patterns that operate recurrently such as, for example, every weekday. (Service patterns that don't repeat such as for a one-time special event will be defined additionally in the calendar dates table.)

The GTFS data tell us about the movement of an entire fleet system. Each stop a train or bus makes is a stop in GTFS. Every stop time is rolled up into a trip. All trips are associated to a route. Each route is broken out by days of travel with the calendar. When auditing a fleet exterior system, Geopath downloads and stores the most recent set of GTFS data directly from the agency website or an open mobility data store (e.g., http://transitfeeds.com ). The data are archived into our own system as a vintaged copy.

Each trip in the GTFS data is routed along the street network, meaning we associate a trip in GTFS with the HERE Maps network by referencing the stop times table. Using the set of streets traversed for each trip, we estimate a weighted vehicles per hour and pedestrians per hour traffic count. The weighting is done by the amount of time the transit vehicle spends on each traversed link based on hourly speed data from HERE Maps.

Circulation

In addition to GTFS, we also collect inventory data for each system. This allows us to move from traffic to circulation, which is the number that considers field of view. Each route in a fleet system (from the routes table in GTFS) is organized into garages and assigned a vehicle type. For each vehicle type, there are multiple placement type options where a frame can be placed.

The inventory attributes of a fleet system that we collect include:

·        Market data capturing general information on the system

·        Garage locations listing the garages and their geocoded locations

·        Quanitity of bus construction types for each garage

·        Available frame by placement type (e.g. driver side, front side, wrap) for each type of bus, listing height/width and frame media names for each. We use industry standard frame media names including queen, full back, taillight, full wrap, king, ultra-super king, kong, half side, full side, headlight, half wrap, mini taillight, mini queen, super king, extended tail, and 30x215.

Circulation is calculated by using the placement of the frame with respect to the direction of traffic. A driver side ad is exposed to both opposing vehicular traffic as well as vehicular traffic traveling in the same direction passing on the left. A passenger side advertisement, however, would only be exposed to vehicular traffic passing on the right-hand side. The following table outlines the details.

Each individual trips in the GTFS data have a circulation number. The trips are grouped into routes, and the routes are grouped by garage. The total circulation of a garage is divided by the number of buses there for an average circulation. Therefore, the circulation is the same for every bus’ placement type within the garage.

Circulation Example - Placement Type

This example provides context of the underlying audience for a driver side full side versus a passenger side full side.

Aerial Imagery

The bus traveling this route is part of the San Diego MTS. The bus is driving on bus route, “3”, heading eastbound towards the Euclid Transit Center.

Open

Circulation Summary by Placement Type

Pedestrian Circulation: The pedestrian circulation for either side of the bus is half of the total pedestrian circulation.

For the driver side, the pedestrians with the opportunity to see the ad are pedestrians on the north side of Market St. traveling in both directions.

With the passenger side, the pedestrians that have opportunities to see the ad are located on the south side of Market St., traveling in both directions.

Oncoming Vehicular Circulation: The driver side ad can be seen by all of the traffic driving in the opposite direction. The passenger side ad cannot be seen by any vehicles moving in the opposite direction.

Same Direction Vehicular Circulation: The driver side ad can be seen by the majority of traffic moving in the same direction of the bus because it is being passed. The bus is moving on average slower than traffic speed because it is consistently making stops.

Traffic is passing more often on the driver side than on the passenger side. In some cases the bus does pass traffic or is passed by traffic on the passenger side.

Circulation Data by Placement Type

The difference between the driver side and passenger side same direction circulation is based on the speed of the bus versus the speed of traffic. The bus moves slower than the average speed of traffic.

The bus is being passed by the majority of the traffic and tallies up circulation of 17,979. The bus also passes a small amount of traffic for a circulation of 1,559.

Legacy vs. Current Impressions by Placement Type

The previous methodology also accounted for the circulation in the same way, but weight averaged the impressions in the reporting.

The legacy reporting methodology applied to the current impressions would have taken the average of 90,491 and 14,077 for an average of 52,284.

Front and Rear Placement Types

Aerial Imagery

This is a Portland Tri-Met municipal bus with a front placed ad in orange and rear placed ad in green. The bus is driving on bus route, “20”, heading eastbound towards Portland City Center.

Circulation Summary by Placement Type

Pedestrian Circulation: The pedestrian circulation for either side of the bus is half of the total pedestrian circulation.

For the front side ad, the pedestrians with the opportunity to see the ad are pedestrians on both the north and south sides of Burnside St. walking in the westerly direction.

For the rear side ad, the pedestrians with the opportunity to see the ad are pedestrians on both the north and south sides of Burnside St. walking in the easterly direction.

Oncoming Vehicular Circulation: The front side ad can be seen by all of the traffic driving in the opposite direction. The back side ad cannot be seen by any vehicles moving in the opposite direction.

Same Direction Vehicular Circulation: The driver side ad can be seen by the all of traffic moving in the same direction of the bus. The bus is either passing a vehicle or being passed by a vehicle so the rear is in view.

The front side ad is not viewable to any traffic moving in the same direction.

Circulation Data by Placement Type

Ped Circulation: The circulation total is 5,374 age 5+ weekly pedestrians.

Oncoming vs. Same Direction Vehicular Circulation: The oncoming traffic of 46,362 is much greater than the same direction traffic of 6,627. There will be many more cars passed in via oncoming traffic than those traveling in the same direction.

Impressions Data by Placement Type

Ped Impressions: The rear ad is slightly larger so the VAI allows for additional impressions.

Oncoming Vehicular Impressions: We see a likely 11,836 of the oncoming traffic 46,361 vehicular passengers register as impressions.

Same Direction Vehicular Impressions: 3,491 of the total 6,627 vehicular passengers registered as impressions.

Impressions by Media Type Summary

The taillight is slightly larger than the headlight but the headlight is expected to deliver more impressions. The high volume of oncoming traffic is the largest contributor.

Opportunity-to-See

For illuminated frames, opportunity-to-see (also referred to as spot opportunity in this case) discounts circulation based on the ad length, layout share of voice, and spot share of voice.

Likelihood-to-See

The VAI for roadside uses a logistic regression to predict the likelihood of seeing an ad (also called noting). The regression considers apparent size, degrees off-center, dwell time, and illumination. The model shows that, as expected, the probability of noting increases with an:

·        increase in apparent size

·        decrease in degrees off-center

·        increase in dwell time

·        illumination

Apparent Size

The apparent size of a piece of inventory is determined by its distance from the audience, its angle from the audience, and its height and width. The following graphic visualizes the effect of angle on the apparent size.

It is the weighted average of the angular size of the board from the perspective of the audience as they travel through the viewshed and while the billboard is in their field of view. Angular size is in degrees and is a rough estimation of the number of degrees in person’s field of view that is occupied by the billboard.

Degrees Off-Center

Degrees off-center is the weighted average of how off center the billboard is with respect to the center of eyesight as a person drives through the viewshed and the board is within their field of view. This variable is a function of (1) the relative heading of the travel path and (2) the perpendicular distance between the road and the billboard.

Dwell time

The dwell time is the time spent traveling within view of the media. The equation considers speed of the audience, size of the media, and distance to the media.

The pedestrian dwell time is the average amount of time a pedestrian is in the viewshed of the advertisement. The dwell time is a calculation based on the transit vehicle speed (which is the same as the speed that the advertisement is moving) relative to the pedestrian speed, assumed at 3.1 miles per hour. A greater dwell time increases the likelihood of seeing the advertisement.

The vehicular dwell time is the amount of time a person in a vehicle is in the viewshed of the ad. The calculation is based on the transit vehicle (and ad) speed relative to the traffic speed. Greater dwell times increase the likelihood of the vehicular audience seeing the ad.

Illumination

True or false indicating whether the media is a digital sign. By digital, we mean that it is a computerized screen.

Accuracy Refinements

Fleet exterior media are now measured with additional accuracy compared to the legacy methodology. There are refinements to the routing, the GTFS schedule, circulation, speed and dwell time, ad placement, and wrapped media. 

Routing

The legacy system measure distance between stops using the Haversine formula, which gives distance as the crow flies rather than on streets. Now the distance is measured over the routed streets between stops, and the actual street segment lengths are summed. If, for example, a bus drives on a curved or turned road, this makes the true distance longer than the straight-line distance. 

GTFS Schedule Data

The GTFS data are used to account for the full schedule of vehicle travel. Weekday, weekend, and holiday schedules were miscalculated in the legacy system, and they were estimated to be occurring every week which overrepresented advertising exposure. The updated methodology recognizes that transit routes have unique weekday, weekend, and holiday schedules that run on specific days and that not every schedule is run weekly.

Circulation

The circulation was derived from the location of the bus stop in the legacy system, rather than from the traversed street segments. Additionally, circulation in the legacy system always included both directions, even in scenarios of split highways or medians, resulting in overstated opportunities to see the ad from the opposing direction.

Given the granularity of the data available now, there is more precision in determining circulation of those that have an opportunity to see the ad. Circulation now only includes the opposing traffic that is within proximity to the vehicle.

Speed and Dwell Time

The speed of vehicle travel was determined from the routed, straight-line distance between stops and the difference between stop times. Average hourly speed was used for most major roadways. Other roadways used default speed by road class.

Hourly speed data are now from HERE Maps instead. The speed of the vehicle in relation to the speed of traffic allows for greater precision when noting the quantity of passing vehicles as well as the dwell time in the advertisement’s contact zone.

Ad Placement

Advertisement ratings applied a weighted average to represent a media type’s presence on the curb side or street side of the vehicle.

The ratings for the scheduled fleet inventory correspond to the advertisement’s placement on the vehicle. Advertisement ratings can now be calculated for all four sides of the vehicle allowing for driver side and passenger side ads to have their own ratings, as well as headlight and taillight ads.

Wrapped Media

The impressions for wrapped media types were previously overstated. Ratings for individual wrap components were not accurately accounted for and therefore ratings were greater than their individual parts. The updated methodology revises the aggregation of circulation for wrapped media types. Impressions for wrapped media types are now representative of their individual parts.

High-Level Validation

Circulation Data

In validating the impressions data, we referenced the changes to the underlying circulation data.

The circulation comparison shows the vehicular and pedestrian circulation across kings and full backs. We are comparing the changes in circulation between the legacy methodology to the current. With respect to vehicular circulation, the current counts are generally fewer than the legacy. This was to be expected due to correcting the crediting of the GTFS calendar references. The pedestrian circulation, however, sees increases. In Chicago Transit Authority, Corvallis Transit System, Regional Transportation of Southern Nevada, and Suffolk County Transit, the current methodology shows greater pedestrian circulation.

Exterior Fleet Pedestrian Impressions

A case study was created between Chicago Transit Authority (CTA) bus exterior ads and bus shelters for comparison purposes. Fleet ads are accumulating on a percentage basis more pedestrian and less vehicular audience than shelters.

On average, a Chicago fleet spot ID finds a circulation count of 70,915 while the average transit shelter spot ID finds 62,183 impressions. These numbers are relatively close to another though the breakdown is different. 47% of the fleet circulation are from pedestrians while only 16% of the transit shelter circulation are pedestrian.

In the case of the transit shelters, the pedestrians are slower moving while the shelter is stationary, resulting in a lower amount of interaction. With the fleet exterior ads, the pedestrians are still slow moving though the ad is passing through at the speed of traffic. This results in a higher rate of interaction with pedestrians.

CTA Exterior Fleet Circulation

(Ped Circulation: Pedestrian Circulation)

(F Veh Circulation: Forward Vehicular Circulation)

(R Veh Circulation: Reverse Vehicular Circulation)

CTA Bus Shelter Circulation

5 Impressions Availability

Impressions will be accessible both in the Insights Suite and via the API. In addition to core demographics (ages 0+, 5+, 18+ and 21+), we will have over 8,000 demographics available. These are derived from the mobile location data and are the same demographics that are available for roadside and place-based inventory.

Attached are current draft measures and OOH Plan average impressions.

Change from OOH Plan to Current Data

• Visitation Data

  • OOH Plan used ridership data, currently we are using a different ridership data source for 2019-2021 data and at mobile device data

• Inventory Information

  • OOH Plan was using assumed attributes such as hours of operation, digital screen type etc. Currently we’ve gathered more granular information

• Methodology

  • The methodology has greatly changed and now matches the auditing process for all Place Based (“in-venue”) inventory. The visitation is split up depending on Placement Type (where within the venue such as Concourse, Platform, Entrance/Exit) and attributes such as number of concourses, platforms etc. From there we have a Frame Circulation where the panel attributes (size, screen type) are considered for a VAI score and calculate impressions.