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Safety & Security Time Series (Threshold Adjusted)

Recent changes to this file by release:

Release Month Change Summary Data Years in File Affected More Details for Data Users
May 2024 FTA has updated its validation procedure for Non-Major S&S events to allow for inclusion in the data publication sooner in certain cases. Users may notice a larger increase in S&S events than normal for certain records in 2023-2024 (only years for which data collection and validation is presently ongoing) compared to prior releases. This is done to allow for a more timely release of validated data. 2023-2024 The applicable Non-Major Event counts are added together with the applicable Major Events counts within this time series. The validation timeframe for Major Events has not changed; events will still be counted in the file as soon as the submitted forms are approved for release, as discussed in January 2024 release update below. Previously, Non-Major Event forms were subject to the same approval process which led to continuity issues between releases. Effective with this release, all reported Non-Major events are counted as long as they occurred by the time series month (e.g., January 2024 for the May 2024 release).
April 2024 The Time Series will count events which involved an assault or homicide and a collision (e.g., a person injured when pushed into a transit vehicle) in the Security Event columns. Previously, these events may have been counted in the Collision column. This change aligns with existing data handling for Collision events that involve Suicide or Attempted Suicide. 2023-Present The Major Safety Events file published to the DOT Open Data Portal has also been updated to account for these events. The Event Type column will now display a converted Event Type (e.g., from Collision to the corresponding Security Event Type, Assault or Homicide). In addition, the Person List field will provide a flag so that users can identify the number people assaulted during the event.
February 2024

FTA will no longer include 2002-2007 data in this file. These data are still available for data users at the following webpage: 

Safety & Security Threshold Adjusted Time Series 2002-2007

2002-2007 This data is not archived and is still available in the database, but FTA has determined it is not subject to change and is simplifying the steps to refresh the monthly datasets.
January 2024 FTA has updated its query logic to allow for the inclusion of relevant S&S events as soon as the events are validated. Users may notice a larger increase in S&S events than normal for certain records in 2023 (only year for which data collection and validation is presently ongoing) compared to prior releases. This is done to allow for a more timely release of validated data. 2023

Previously, late submissions or changes to S&S event details would have resulted in the exclusion of the given event for two release cycles to allow sufficient time for data validation. Now, any validated event that occurred by the time series month (e.g., September 2023 for the January 2024 release) will be included in the Time Series.

For more detail on which events were added, please consult the DOT Open Data Catalog Major Safety & Security Events file linked below.

October 2023

1. FTA has now incorporated data for all years onto one tab for ease of use by data processing systems which pivot along report year. Report Year is added as the first column in each tab. All other data is preserved in its original format.

2. FTA has removed UZA Number which no longer serves a purpose since UACE Code uniquely identifies each Urbanized Area.


The file is ordered by Reporter, Mode, and Type of Service for easy visual comparison of data across years for a given NTD Reporter, Mode, and Type of Service.

As described below, the column for Transit Worker Assaults (Events) includes a derivation of Transit Worker Assaults for years 2022 and prior that is based on the person type and event type.

August 2023

FTA has added three new columns to reflect Assaults on Transit Workers data collection which is a mandatory data collection effort described in the Bipartisan Infrastructure Law (BIL). The effort, which began in April 2023 introduces Assault on a Transit Worker as a new Major Event Type available to NTD reporters in Report Year (Calendar Year) 2023. A data definition for each new column is provided within.


An Assault on a Transit Worker can be described as a circumstance in which a transit worker is assaulted (for a full definition, please see the NTD Glossary). Consequently, the three new columns provided in the "Events" section are not counts of injuries resulting from assault nor are they the total number of people assaulted. The datasets linked below provide more detail for data users interested in approximating such aggregates.

In years prior to 2023, counts of Assaults on Transit Workers are derived with an estimated 99%+ accuracy using the Person Type of the injured party. Data users should therefore take caution that a very small number of events classified as "Assault Events Involving Transit Workers" do not actually involve an assault against a worker as defined in 2023.

Because Non-Major Events were historically not reported to the NTD, Non-Major Assaults on Transit Workers are not reported.

July 2023 FTA has added the column "UACE" which will, in future months, uniquely identify each Urbanized Area. ALL YEARS This allows users to more easily filter to modes operating in a certain Urbanized Area (UZA) regardless of when they operated. In future months, the UZA number previously provided will be replaced with this code.

Adjustments for historical continuity:

This time series combines Major and Non-Major event data reported to the NTD. It also makes the following adjustments to the scope of Safety & Security (S&S) events included in the file to prevent a large imbalance in event accounts that are due to changes in reporting thresholds.

  2002 - 2010 2011 - 2014 2015 - 2022 2023
Major Events All Included Excludes:
Yard Derailments and Rail Grade Crossing Collisions not meeting other Major Event reporting threshold
Non-major Events Excludes: Security Events All Included (Non-Major Security Events not reported to the NTD) Excludes: Security Events (Assaults on Transit Workers)

For more information about current thresholds, see the most current S&S Quick Reference Guide from this page

Other considerations for data users:

  • This file will be updated periodically by FTA to include data for subsequent months, and to incorporate revisions to prior months in the calendar year made by the transit properties. This may include revisions to data from the previous calendar year, especially in the first several months of each new calendar year, as CEO Certifications are ongoing. The Time Series counts injuries and fatalities associated with Suicide events in the Suicide column and recently updated the file to perform the same adjustment for Attempted Suicide events as well. These classifications are made to retain consistent data definitions from year to year and there are no net changes in total number of events, injuries or fatalities as a result.
  • FTA is now releasing on a monthly basis the source datasets for this file for all events starting in 2014. This file provides a record for each Major and Non-Major Event reported to the NTD with some details about the event. Please find the datasets on the DOT Open Data Catalog website.
  • From 2016-Present, the data available in the NTD regarding Suicides is more precise; people who are harmed in a suicide-related event but were not identified as the person attempting suicide are classified according to the reported Person Type (e.g., Passenger, Employee, etc.). In years before 2016, such individuals are counted as Suicide or Attempted Suicide injuries due to reporting requirements. Data users should consider this level of precision when using Suicide column data. 
  • The NTD categorizes Non-Transit Collisions, events which do not involve transit vehicles, as Not Otherwise Classified (NOC) event type. The 2008-Most Current Year tabs do not include these events in the Collisions column and instead include these events in the respective NOC column. This results in a net decrease in collisions and an equal increase in NOC safety events compared to what was reported but does not affect total number of events, injuries or fatalities.

Keywords: non-major, major, event, collision, derailment, fire, security, noc, passenger, people waiting or leaving, bicyclist, pedestrian, in cross, not in crossing, operator, employee, other, vehicle occupant, other, trespasser, suicide, safety statistics, security statistics

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