According to AAR, hazardous materials comprise about 8 percent of commodities shipped by rail in North America--about 2.35 million out of 29.4 million annual carloads shipped in 2015. According to the most recent Bureau of Transportation Statistics data available (2012), railroads ship about 4 percent of the hazardous materials in the United States by tonnage, but railroad shipments account for about 28 percent of distance traveled by hazardous materials. The freight railroad industry is dominated by the seven Class I railroads, which transport the majority of freight--including hazardous materials--in freight containers, portable tanks, and other types of rail cars, including tank cars that travel across a network of 140,000 miles of track. In addition, numerous Class II and hundreds of Class III railroads have essential roles in moving freight, typically linking rural communities to the larger railroad network. Often providing "first mile" and "last mile" movements, these smaller railroads, taken together, operate on 50,000 miles of track or nearly 40 percent of the national railroad network and handle in origination or destination one of every four cars moving on the national system. PHMSA, through its Office of Hazardous Materials Safety, regulates shippers and railroads transporting hazardous materials by rail and other modes. One way PHMSA fulfills this mission is through the promulgation of the HMR for the safe transport of hazardous materials. These regulations pertain to the classifying, handling, and packaging of shipments of hazardous materials, including rail shipments, and include seven requirements that emergency response information must include for each hazardous material being shipped. These are: 1. The basic description and technical name of the hazardous material. 2. Immediate hazards to health. 3. Risks of fire or explosion. 4. Immediate precautions to be taken in the event of an accident. 5. Immediate methods for handling fires. 6. Initial methods for handling spills or leaks in the absence of fire. 7. Preliminary first aid measures. The HMR also require railroads to have a document, often referred to as the train consist, that identifies basic information about the position in the train of each rail car containing hazardous materials. The consist also typically includes information on the train's contents, including basic descriptions of the hazardous materials transported, and their destinations, and may include supplemental emergency response information, such as details on how to respond to releases of specific hazardous materials. FRA provides regulatory oversight for passenger and freight rail, issuing and enforcing safety regulations through its Office of Railroad Safety. FRA enforces the HMR and its own regulations through inspections and audits by FRA officials, including about 400 federal safety inspectors and state partners in some states. For example, according to DOT officials, FRA conducts inspections to ensure that railroads carry the required emergency response information mentioned above as well as an emergency response telephone number in train documentation and conduct and keep records of required general-awareness and function- specific hazardous material training for train crews. When a rail accident occurs, local emergency responders--police, emergency medical technicians, and firefighters--and railroad train crews are typically first on the scene of, and often provide the initial response to, a rail accident involving hazardous materials. For example, local and sometimes regional officials may be responsible for advising the public on taking shelter-in-place actions or conducting evacuations of affected populations. In addition, assuming the crews are not affected by an accident, railroad train crews are expected to provide local emergency responders with information about the position, type, and quantity of hazardous materials on the train as well as written emergency-response and contact information for the specific commodities (see fig. 1). The HMR also requires railroads to provide immediate notice of certain hazardous materials accidents to the National Response Center. The ERG, published every 4 years by PHMSA, is a 400-page document that contains emergency response information for thousands of hazardous materials and for all modes of transportation. It is intended to help first responders identify the characteristics of the hazardous materials involved in an accident through a table of markings, labels, and placards, specific risks associated with the hazardous materials how first responders can protect themselves, and procedures for containing the accident as quickly and safely as possible. The ERG is organized into four color-coded sections to help users navigate the document. For example, the orange section of the ERG divides hazardous materials into 63 categories--such as flammable liquids-toxic, flammable gases, and oxidizers --with an individual guide for each that provides information on types of potential hazards each category poses, including health, fire, or explosion hazards. The green section provides specific information, such as initial isolation and protective action distances for small or large spills occurring during the day or night, for hazardous materials that are considered to be a toxic inhalation hazard (see fig. 2). To assist railroads in complying with the HMR, AAR, with the input of railroads, develops and makes available to all subscribing railroads the United States Hazardous Materials Instructions for Rail, which provides general guidelines to the train crew on handling hazardous material shipments or incidents safely and efficiently and in accordance with local, state, and federal regulations. For example, this document provides information on required emergency response information, how the train crew and emergency responders are to interact, and what to do when a fire or vapor cloud is visible. This document also recommends that train crews carry the ERG. Selected railroads typically carry two sources of emergency response information--the train documents and the ERG--to meet the emergency response information requirements in federal regulations. Our review of selected train documents determined that they always contained the position and content of rail cars and the basic descriptions of hazardous materials on board the train. In addition, our analysis determined that the train documents sometimes included supplemental emergency response information. Fifteen of the 18 railroads we spoke with told us that they use AAR's United States Hazardous Materials Instructions for Rail as their guidance for meeting train documentation requirements, including emergency response information. According to the train crews' unions, the ERG and the train documents are kept in the locomotive of the train by the train crew, usually a conductor and an engineer. According to FRA and PHMSA officials, the ERG's use is not required by regulation, but is viewed by the rail industry as a national standard for emergency response information requirements. All railroads that we interviewed told us that the ERG is carried aboard its trains as a source of emergency response information. For shipments of hazardous materials, the HMR requires the train crew to carry documents with specific information about the hazardous materials on board. Our review of selected train documents showed that the selected railroads included this information in their train documents. Additionally, most of the selected railroads included the information in their train consist, which identifies the position in the train of each rail car and includes other information about the rail car, such as its contents and destination. This information includes a basic description of each hazardous material being transported on that train, including the identification number and proper shipping name, as well as an emergency response telephone number, which is provided by the shipper of the regulated hazardous material (see fig. 3). This telephone number is required to be located on documentation carried by the train crew on the shipping documents for transportation of the material. This basic description of the hazardous material the train is transporting meets the first of seven emergency-response information requirements in the HMR. Our review revealed that some railroads also include supplemental emergency response information for each hazardous material on the train at the end of the train consist or in a separate document. According to AAR, it provides this information to some railroads from its Hazardous Materials Emergency Response Database, which AAR develops and maintains. Six of the 7 Class I railroads and 5 of the 11 selected Class II and III railroads included this supplemental information in their trains' documents. Our analysis showed that the amount and content of the supplemental emergency response information varied depending on the number and type of hazardous materials being transported on a train. For each hazardous material on the train, the information can include 5 to 10 paragraphs, covering 1 to 2 pages of paper. Supplemental emergency response information may include information on how to handle fires; precautions to be taken in the event of an accident; first aid responses; or how to handle air, water, or land spills for that particular hazardous material (rather than groups of hazardous materials as with the ERG). AAR told us the railroads carry this information because, prior to the development of the ERG, it was the only source of emergency response information carried on trains. However, as discussed later, AAR plans to discontinue the use of this database because, among other reasons, new sources of information, along with the ERG, have become available to emergency responders that contain this type of information. According to the four emergency response associations we spoke to, when responding to a rail accident involving hazardous materials, emergency responders primarily rely on information from the train documents and the ERG during the first 30 minutes. These associations and two local responders we spoke to told us that responders will want to immediately learn what hazardous materials are on the train and their exact location. There are a couple of ways a responder might begin to identify what is on the train. According to all selected responders, if the train crew is located quickly, responders would use the train documents to identify and locate the hazardous materials on the train. If the train crew is incapacitated or cannot be found right away, responders could use placards, labels, or markings on the train to identify the hazardous materials, according to one emergency response association. According to four emergency response associations, responders then may consult the ERG to gather more information about the hazardous materials. PHMSA, the four emergency response associations, and one local responder told us that the ERG is the go-to source for first responders during the first 30 minutes or initial phase of an accident. In addition, two selected responders told us that the train documents are the best source for the most updated list of the hazardous materials on the train and their locations. According to officials from two emergency response associations, emergency response should be thought of in terms of an accident timeline. According to these officials, the goal of emergency responders is to obtain more specific and detailed information as time goes on, beyond the first 30 minutes. During the management of an accident, emergency responders move from having unknowns to knowns. According to four emergency response associations and two local responders we interviewed, as the incident timeline matures, a responder should be seeking more comprehensive sources of information on the hazardous materials involved in the incident (see fig. 4). One emergency response association told us that a responder might consult CHEMTREC, the Wireless Information System for Emergency Responders (WISER) application, the National Institute for Occupational Safety and Health (NIOSH) Pocket Guide to Chemical Hazards, or hotlines for the hazardous materials shippers themselves to obtain more specific information on chemical properties or tactical information. Below is an example of a sequence of actions a responder might take in the event of a hazardous materials accident, according to our analysis and interviews: A responder must first identify the hazardous material involved and its location. This could occur using the train documents from the train crew if they are located quickly, or if the train crew is incapacitated or cannot be found right away, using placards, labels, or markings on the train. Next, the responder determines initial response actions. Using the ERG, the responder might locate the material in the ERG and determine which of the 63 guides (orange section) applies. These guides provide the basic hazardous material information that a responder might want to know immediately, such as evacuation distances, risks of fire or explosions, potential health hazards, or protective clothing to wear. If the hazardous material is a toxic inhalation hazard, the ERG would direct a responder to its green section to gather additional information on isolation and protective action distances for small and large spills during the day or night. After locating the train crew and the train documents, a responder might also consult the supplemental emergency-response information in the train's documents for specifics about the hazardous materials involved in the accident. The new AskRail app, developed by AAR with data from all the Class I railroads, is another tool that provides first responders immediate access to information about the hazardous materials on the train. It provides access to real-time train consist information and corresponds directly to the emergency response information in the ERG associated with each hazardous material on the train. Later, after the material has been identified and initial response actions have been taken, a responder could consult previously mentioned sources such as WISER or CHEMTREC about the reactivity of the chemical, suggested environmental response measures, or suggested first aid measures for that particular hazardous material rather than a group of hazardous materials. The interaction between the train crew and emergency responders after a rail accident is important because it is the train crew who must provide train documents to the responders that lets them know the rail car order, the contents of the rail cars, and emergency response information for any hazardous materials that the train is transporting. The United States Hazardous Materials Instructions for Rail provides guidelines for how this interaction between the train crew and responders is to occur. Each railroad may modify parts of the United States Hazardous Materials Instructions for Rail to reflect their individual policies. Our analysis of the instructions provided by selected Class I, II, and III railroads found that they had generally consistent guidance on train crew cooperation with emergency responders. In each of the instructions that we reviewed, the train crew is expected to immediately share any requested information from the train documents with emergency response personnel. In addition, the train crews are instructed to help emergency response personnel identify the rail cars and commodities involved, using train documents or observation from a safe distance. Five of the seven Class I railroads added information to their hazardous materials instructions on the process for sharing information with emergency responders. As an example, the guidance of one Class I railroad says, "If an extra copy is not available, share (DO NOT SURRENDER) the copy you have with the emergency response personnel." One Class II railroad asks its employees to note the time, along with the name and title of the person provided with the (emergency response) information. Training received by emergency responders informs the emergency response actions taken following a rail hazardous materials accident. For example, according to one emergency response association we interviewed, emergency responders with basic training, called awareness level training, receive training on the ERG, how to read train documents, and the other sources of emergency response information that provide more specific information on hazardous materials. On the other hand, according to one emergency response association and one local responder, responders with more advanced training may consult other sources of information even in the first 30 minutes of a response. For example, a hazardous materials technician for a local responder in Montgomery County, MD, told us that he does not use the ERG, but instead relies on the NIOSH pocket guide in the first 30 minutes of an incident because it provides more precise information than the ERG. Training for emergency responders may be provided by emergency response associations, railroads, or state and local emergency management agencies, among others. According to PHMSA, PHMSA also conducts outreach to emergency responders to train them on the ERG, including any changes to the ERG if a new version is forthcoming. For example, PHMSA officials visited 46 firehouses in fiscal year 2016-- including visits in Olympia, WA, Houston, TX, and Greenville, SC-- to provide training on the ERG. PHMSA also developed a new online training program in April 2016 that introduces emergency responders to the hazardous materials regulations and that may also be used to meet the requirements for awareness level training, or as the basis for developing more advanced training programs. The content in the ERG and the supplemental emergency response information in the train documents we reviewed was generally similar, largely aligning with the seven categories of required emergency response information for hazardous materials shipments set forth in the HMR (see table 1). We used the seven requirements in the code of federal regulations as a baseline by which to compare the ERG and supplemental emergency response information. The specific content was the same in certain instances. For example, both sources recommended that, in response to an incident involving propane, responders move victims to fresh air and give them artificial respiration if they are not breathing. The existence of identical content was, in part, because the ERG was one of the sources for the information in the AAR Hazardous Materials Emergency Response Database, which, as discussed earlier, was the source of the supplemental emergency response information in the train documents we reviewed. While the general content and certain information in the ERG and the supplemental emergency response information we reviewed was similar, the ERG mostly provided emergency response information for groups of hazardous materials based on their general hazards, while the supplemental emergency response information was specific to each hazardous material onboard the train (see table 1). The supplemental emergency response information that we reviewed was intended to augment the ERG and provided more specificity in certain areas. For example, for an incident involving chlorine, the supplemental emergency response information we reviewed recommended digging a pit, pond, lagoon, or holding area to contain the spill, while the ERG generally recommended preventing entry of the spill into waterways, sewers, basements, or confined areas, but did not offer a specific means by which to do so. Additionally, for an incident involving sodium hydroxide solution-- which is commonly present in commercial drain and oven cleaners-- the supplemental emergency response information we reviewed recommended the use of specific materials for protective clothing, such as butyl rubber and neoprene, while the ERG generally recommended wearing protective clothing recommended by the manufacturer of the hazardous material. The supplemental emergency response information we reviewed also provided information that went beyond what is required by federal regulations and included in the ERG, such as physical characteristics of the hazardous material, uses, water solubility, and environmental hazards. However, in one area, the ERG often provided more detail than the supplemental emergency response information we reviewed. The ERG provided specific initial isolation and evacuation distances for incidents involving groups of hazardous materials, while the supplemental information offered no distance recommendations or deferred to the ERG in most of the train documents we reviewed. For example, for a large spill of gasoline, the ERG recommended an initial downwind evacuation of at least 300 meters, while the supplemental emergency response information we reviewed said to consult the ERG for all evacuation distances. The ERG and the supplemental emergency response information we reviewed also at times differed on the type of information that was given for certain emergency response recommendations. For example, for handling spills or leaks, the ERG often provided recommendations according to the size of the incident, such as small or large spills, while the supplemental information we reviewed often provided recommendations according to the environment, such as air, land, or water spills. In reviewing the ERG and train documents in our nonprobability sample belonging to our selected Class I, II, and III railroads, we found inconsistent information for 8 of the 72 hazardous materials we selected. Two inconsistencies involved differences in a first aid response recommendation regarding the amount of time to flush skin or eyes with running water in case of contact with the substance. The differences were 5 minutes in one instance and 10 minutes in another. Six inconsistencies involved discrepancies between the recommended evacuation distances in the two sources. o For four of the six hazardous materials with evacuation distance inconsistencies, the supplemental emergency response information recommended an evacuation distance of a half mile for an incident involving fire, while the ERG recommended one mile. These four hazardous materials were all labeled as United Nations identification number 1075, which represents multiple liquefied petroleum gases. o For another of the hazardous materials, sodium chlorate, the ERG recommended an evacuation distance of a half mile, while the supplemental emergency response information recommended the same distance, but only if the resulting fire was uncontrollable. o For the final hazardous material, ammonium nitrate, the ERG recommended an evacuation distance of a half mile in all directions for an incident involving fire, while the supplemental emergency response information recommended one mile for an uncontrollable fire. The NTSB report on the Paulsboro, New Jersey, incident highlighted inconsistencies between recommended evacuation distances in the supplemental emergency response information in the train documents and the ERG for two of the hazardous materials on the train, chlorine and vinyl chloride. This finding led to NTSB's recommendation that AAR update its database to ensure that its guidance is consistent with and at least as protective as the ERG. In response to NTSB's recommendation, AAR replaced all existing evacuation distance statements in its Hazardous Materials Emergency Response Database, effective August 1, 2014, with a statement to consult the ERG for protective action considerations, including initial isolation or evacuation distances and shelter-in-place recommendations. Additionally, AAR made other changes to the database effective December 1, 2014. NTSB found AAR's response actions to be unacceptable because AAR did not revise emergency response information that was less conservative than the equivalent precautions contained in the ERG. As described above, our analysis showed that some railroads did not capture these changes, including the new evacuation distance recommendations, and continued to provide specific evacuation distances for hazardous materials in their train documents that were inconsistent with the ERG. AAR is planning a change that is intended to remove the potential for such discrepancies. Specifically, according to AAR, AAR hazardous materials committee members--which consist of representatives of the 7 Class I railroads--unanimously voted in August 2016 to discontinue the support, production, and distribution of the AAR Hazardous Materials Emergency Response Database. According to AAR, although the Class II and III railroads did not vote on the change, the database will no longer be supported, produced, or distributed, making it effective for all railroads. Since emergency responders have access to the ERG and other resources with more specific information than the ERG--such as WISER, the NIOSH pocket guide, safety data sheets, CHEMTREC, and the shipper--the supplemental emergency response information has become obsolete, according to one AAR official. We provided a draft of this report to DOT and NTSB for their review and comment. DOT provided a technical comment about hazardous material training requirements, which we incorporated. NTSB provided a technical comment about AAR's response to their recommendation to revise discrepancies between emergency response information found in AAR's database and the ERG, which we incorporated. We will send copies of this report to the appropriate congressional committees and to the Secretary of Transportation and the Chairman of the National Transportation Safety Board. In addition, the report will be available at no charge on the GAO website at http://gao.gov. If you or your staff have any questions about this report, please contact Susan Fleming at (202) 512-2834 or flemings@gao.gov. Contact points for our Offices of Congressional Relations and Public Affairs may be found on the last page of this report. Major contributors to this report are listed in appendix II. Our objectives were to examine: (1) what emergency response information is carried on trains by selected railroads that transport hazardous materials and how responders use it and (2) how the supplemental emergency response information carried on trains of these railroads compares to the information in the Emergency Response Guidebook (ERG). To inform both of our objectives, we reviewed relevant literature, including the National Transportation Safety Board (NTSB) report on the Paulsboro, New Jersey incident, the ERG, and a prior GAO report on emergency response to rail incidents. We reviewed the Association of American Railroads' (AAR) United States Hazardous Materials Instructions for Rail, to understand industry guidelines on how to meet federal hazardous material regulations, including the emergency response information to be carried on trains and how railroad personnel are expected to interact with first responders. We also examined relevant sections of the Hazardous Materials Regulations (HMR) to determine requirements for railroads related to emergency response information carried on trains transporting hazardous materials. Additionally, we interviewed officials from the Pipeline and Hazardous Materials Safety Administration (PHMSA) and the Federal Railroad Administration (FRA) within the Department of Transportation (DOT) and NTSB to understand their roles in developing, regulating, and making recommendations regarding emergency response information on trains. To identify what emergency response information is carried on trains by selected railroads that transport hazardous materials and how responders use it, we interviewed two railroad associations, AAR and the American Short Line and Regional Railroad Association (ASLRRA), and all seven Class I railroads. ASLRRA told us it represents approximately 450 of the about 550 Class II and III railroads, of which 300 to 400 transport hazardous materials. We selected seven Class II and seven Class III railroads that carry hazardous materials and are ASLRRA members, using PHMSA's Office of Hazardous Materials Safety Incident Reports Database and a member list provided by ASLRRA. We searched PHMSA's database for railroads that experienced an incident in transit during 2015, which resulted in a list of railroads that carry hazardous materials that we could cross-reference with the ASLRRA member list. The railroads we selected are also geographically distributed across the United States. Of those fourteen selected Class II and III railroads, we spoke with representatives of five Class II and six Class III railroads. The other three did not respond to our requests for an interview. The results of the interviews cannot be generalized to the entire population of Class II and Class III railroads. As described below, we also reviewed information on hazardous materials in selected train documents from some of these railroads. Fifteen (7 Class Is, 4 Class IIs, and 4 Class IIIs) of the 18 railroads we interviewed provided us with at least one set of train documents. We selected one set of train documents from each of those railroads to determine how the basic description and technical name of hazardous materials the train is transporting and the emergency response telephone number are displayed. The results of the analysis are not generalizable to all of the train documents of the selected railroads or all railroads. We also spoke with CHEMTREC regarding its role in providing information to first responders. Additionally, we interviewed three of the five largest shippers of hazardous materials in the United States--Exxon- Mobil, Dow Chemical Company, and BASF--to determine what emergency response information they provide to railroads and emergency responders. CHEMTREC identified and provided the contact information for the three shippers based on their criteria and resources. We also interviewed local emergency responders in Montgomery County, MD, Westmoreland County, PA, and Culbertson, MT to learn their perspective on the emergency response information carried on trains and how and when emergency responders use the information. We chose the first organization because of its proximity to the audit team in Washington, D.C. and the other two because of their involvement in responding to rail incidents involving hazardous materials in 2014 and 2015, respectively. We determined their involvement by searching PHMSA's Incident Reports Database for serious rail incidents in transit over the last 5 years that resulted in a hazardous materials' release and talking to the first responders associated with the city or county listed in the database. We also interviewed representatives from four emergency response associations--three national associations representing local emergency responders, including the International Association of Fire Chiefs, International Association of Firefighters, and the National Volunteer Fire Council, as well as the National Fire Protection Association, which develops, among other things, standards for emergency response to hazardous materials incidents. Additionally, we spoke with two train crew unions--the Brotherhood of Locomotive Engineers and Trainmen and the International Association of Sheet Metal, Air, Rail and Transportation Workers--to understand the role of the train crews in emergency response and how they interact with emergency responders following a rail incident. To understand how the supplemental emergency-response information carried on trains of selected railroads compares to the information in the ERG, we analyzed information on a nonprobability sample of hazardous materials discussed in the ERG and in train documents. We used the 2012 ERG, as opposed to the recently released 2016 ERG, because not all of selected railroads had begun using the 2016 version during the timeframe that the sample was taken. We asked each of the 18 railroads that we interviewed to provide us with a nonprobability sample of their train documents, including the "train consist" and any supplemental emergency response information, for 15 trains carrying at least two different hazardous materials and traveling between May 12, 2016, and June 30, 2016. Eleven of the 18 railroads (6 Class Is, 2 Class IIs, and 3 Class IIIs) provided train documents that contained supplemental emergency response information. From those train documents, we selected a sample of 72 unique hazardous materials that were in either the AAR's top 125 hazardous commodities list as measured by loaded tank car originations or top 25 hazardous commodities list as measured by loaded non-tank-car originations (e.g., intermodal trailers or containers on flat cars) in 2014. The sample represented 70 unique sets of train documents from 10 of the 11 railroads that carried the supplemental emergency response information. The sample included 10 hazardous materials in 10 sets of train documents from five of the six Class I railroads, 10 in 8 sets of train documents from the sixth Class I railroad, 5 in 5 sets of train documents from both Class II railroads, and 1 in 1 set of train documents from two of the three Class III railroads. To make the comparisons, we first determined which parts of the ERG and the supplemental emergency response information in the train documents contained information that is associated with the seven requirements for emergency response information outlined in the HMR. We then examined each hazardous material in the sample by comparing the relevant sections in each source and determining where there are similarities and differences, as well as any conflicting information. The results of our analysis are not generalizable to all train documents or all hazardous materials in the ERG. Furthermore, AAR provided us access to its Hazardous Materials Emergency Response Database. We determined that the supplemental emergency response information associated with the sample of hazardous materials in the reviewed train documents from the 10 railroads was reliable for the purposes of our report and objectives because all of the information came from the AAR Hazardous Materials Emergency Response Database. We determined that the database was the appropriate source of the information in the reviewed train documents through interviews with officials from each of the 10 railroads. We compared the supplemental emergency response information on the sample of hazardous materials in the reviewed train documents to the information on those hazardous materials in the source database for the time period reflected by the dates of the train documents (May 12, 2016, to June 30, 2016). The results of our analysis are not generalizable to all train documents or all hazardous materials in the AAR Hazardous Materials Emergency Response Database. We also interviewed supply chain software providers ShipXpress and GE Transportation to learn how the Class II and Class III railroads receive access to the AAR Hazardous Materials Emergency Response Database. We conducted this performance audit from March 2016 through December 2016 in accordance with generally accepted government auditing standards. Those standards require that we plan and perform the audit to obtain sufficient, appropriate evidence to provide a reasonable basis for our findings and conclusions based on our audit objectives. We believe that the evidence obtained provides a reasonable basis for our findings and conclusions based on our audit objectives. In addition to the individual name above, Nancy Lueke (Assistant Director), Kieran McCarthy (Analyst in Charge), Moira Lenox, Garrett Riba, Josh Ormond, William Egar, Dave Hooper, Delwen Jones, Reuben Montes de Oca, and Kelly Rubin made key contributions to this report.

Summary:
In November 2012, a train derailed in Paulsboro, New Jersey, releasing about 20,000 gallons of vinyl chloride, a hazardous material. The National Transportation Safety Board (NTSB) found, among other issues, that the supplemental information in the train's documents on responding to emergencies involving vinyl chloride was inconsistent with and less protective than emergency response guidance in the ERG . Congress included a provision in statute for GAO to evaluate the differences between the emergency response information carried by trains transporting hazardous materials and the ERG guidance. This report examines (1) what emergency response information is carried on trains by selected railroads transporting hazardous materials and how responders use it, and (2) how selected railroads' supplemental emergency response information compares to information in the ERG . GAO reviewed the ERG and other relevant literature and met with DOT and NTSB officials, among others. GAO interviewed all 7 larger Class I railroads and 11 smaller Class II and III railroads that carried hazardous materials in 2015. GAO compared the supplemental emergency response information with ERG information for 72 frequently shipped hazardous materials from a nonprobability sample of train documents provided by 10 of the 18 selected railroads. To help emergency responders safely handle rail accidents involving hazardous materials, selected railroads transporting hazardous materials typically carry two sources of information: the Department of Transportation's (DOT) Emergency Response Guidebook ( ERG ) and information in the trains' documents. Federal Hazardous Material Regulations require railroads and other hazardous material transporters to carry emergency response information that describes immediate hazards to health and risks of fire or explosion, among other things. Representatives from all 18 railroads GAO interviewed told us that they carry the ERG on their trains. According to DOT officials, the ERG's use is not required by regulation, but the rail industry views it as a national standard for emergency response information. Our review of selected train documents showed that they always have a basic description of each hazardous material being transported, including the identification number and proper shipping name, as well as an emergency response telephone number. Six of the 7 Class I railroads and 5 of the 11 selected Class II and III railroads also included emergency response information in these documents. According to four emergency response associations, in the first 30 minutes after a rail incident, emergency responders primarily use the train documents to locate and identify hazardous materials and use the ERG to identify potential response actions. ERG differed from the supplemental emergency response information which is provided by the Association of American Railroads' (AAR) Hazardous Materials Emergency Response Database. AAR decided in August 2016 to discontinue the database, removing the potential for discrepancies between the ERG and the supplemental emergency response information from AAR going forward. GAO is not making recommendations. DOT and NTSB provided technical comments, which GAO incorporated.