Safety Advisory 2007-03

AGENCY:

Federal Railroad Administration (FRA), Department of Transportation (DOT).

ACTION:

Notice of Safety Advisory; Railroad Bridge Safety—Explanation and Amplification of FRA's “Statement of Agency Policy on the Safety of Railroad Bridges.”

SUMMARY:

FRA is issuing Safety Advisory 2007-03 recommending that owners of track carried on one or more railroad bridges adopt safety practices to prevent the deterioration of railroad bridges and reduce the risk of casualties from train derailments caused by structural failures of such bridges.

FOR FURTHER INFORMATION CONTACT:

Gordon A. Davids, P.E., Bridge Engineer, Office of Safety Assurance and Compliance, FRA, 1120 Vermont Ave., NW., RRS-15, Mail Stop 25, Washington, DC 20590 (telephone 202-493-6320); or Sarah Grimmer, Trial Attorney, Office of Chief Counsel, FRA, 1120 Vermont Ave., NW., RCC-12, Mail Stop 10, Washington, DC 20590 (telephone 202-493-6390).

SUPPLEMENTARY INFORMATION:

FRA published its “Statement of Agency Policy on the Safety of Railroad Bridges” (“Policy”) on August 30, 2000 (65 FR 52667). The Policy Statement, included in the Federal Track Safety Standards (Title 49, Code of Federal Regulations, Part 213) as Appendix C, includes non-regulatory guidelines based on good practices which were prevalent in the railroad industry at the time the Policy was issued.

FRA has examined reports from January 1, 1982 through December 31, 2006 of 52 train accidents caused by the catastrophic structural failure of railroad bridges, an average of two per year. During that twenty-five year period, two people were injured and no fatalities were attributed to structural bridge failure. In addition, since the examination of those reports in April of 2006, FRA has learned of four instances where lack of adherence to the guidelines in the Bridge Safety Policy resulted in trains operating over structural deficiencies in steel bridges that could very easily have resulted in serious train accidents. It should be noted that FRA uses the term “catastrophic failure” to describe an incident in which a bridge collapses or directly causes a train accident. A simple “bridge failure” is a situation in which a bridge is no longer capable of safely performing its intended function.

During the past sixteen months, three train accidents occurred due to catastrophic structural failures of bridges, all of which were timber trestles. The most recent bridge-related train accident occurred on the M&B Railroad near Myrtlewood, Alabama, where a train of solid-fuel rocket motors derailed when a timber trestle railroad bridge collapsed under the train. Several cars, including one car carrying a rocket motor, rolled onto their sides and six persons were injured. FRA has also recently evaluated the bridge management practices of several small railroads, and found that some had no bridge management or inspection programs whatsoever.

FRA therefore issues this non-regulatory Safety Advisory to supplement and re-emphasize the provisions of the Policy on the Safety of Railroad Bridges. FRA recognizes the potential impact of regulations related to structural integrity of railroad bridges. However, should these serious incidents and failures continue and FRA determines that the responsible track owners are not conforming to accepted engineering principles and procedures, including those outlined herein and in the Bridge Safety Policy, FRA might have to change course and develop a regulatory approach.

FRA Bridge Safety Evaluations

FRA has been evaluating bridge management practices on a representative sampling of the Nation's railroads, including class I, II and III freight railroads, and passenger carriers. The evaluations generally compare a railroad's program with the guidelines in the FRA Bridge Safety Policy, and include observations of individual bridges to determine their general condition, as well as the accuracy of the railroad's inspection reports.

Most large railroads generally conform to the FRA guidelines, but FRA has discovered instances where management had not adequately evaluated or addressed critical items delineated in railroad bridge inspection reports before they developed into critical failures or near-failures. Many of the smaller railroads evaluated also conformed generally to the guidelines, but a considerable number either fell short by a large degree, or showed absolutely no evidence of bridge inspection, management or maintenance.

This Safety Advisory

As serious gaps exist between the FRA Bridge Safety Guidelines and the actual practices on many railroads, and because FRA has discovered some extremely serious hazards as a result, FRA is issuing this Safety Advisory. Its purpose is to explain and amplify the provisions of the Bridge Safety Guidelines, and to discuss and make recommendations concerning some points in addition to the guidelines that FRA has determined are critical to bridge safety.

Conformance with the FRA Bridge Safety Guidelines

Certain provisions of the FRA Bridge Safety Guidelines are critical from the standpoint of immediate safety to the development and implementation of a railroad's bridge management program. These points are reiterated and expanded below.

Responsibility for the Safety of Railroad Bridges

FRA has specified that the owner of the track carried by a bridge is responsible for the safety of trains that operate over that track, and therefore the track owner must know that the track is being adequately supported by the bridge. Even though the Guidelines are published as an appendix in the Federal Track Safety Standards for convenience, that does not imply that the track owner need only assure compliance with the minimum requirements of the Track Standards. Track conditions that are well within the limits of the Track Standards might also be valid indications of imminent bridge failure.

The owner of the track supported by a bridge is fully responsible for the safety of trains that operate over that bridge, regardless of any agreements, or division of ownership or maintenance expense, to the contrary. The track owner must be able to control, and restrict if necessary, the movement of trains on any segment of its track, including the track on a bridge.

Capacity of Railroad Bridges, and Bridge Loads

The capacity of a bridge, and the actual loads that it carries, are so interrelated that they must be considered together.

The load a bridge carries directly affects its serviceable life and safety. These loads, and various external influences, impose forces on the various components of the bridge. These components, in turn, are each capable of carrying a certain level of forces without failing or rapidly deteriorating.

Every properly designed railroad bridge is configured and proportioned so that it will safely handle the forces developed by a certain train load, together with effects associated with that load. That load, termed the “design load,” is the general basis for determining the safe capacity of a bridge. The design load is, most typically, a series of wheel loads of defined weight, with spacings between every pair of wheels of a defined distance. The bridge must also be capable of carrying its own weight, the weight of other objects permanently attached to the bridge, such as signals and pipes, and other external forces, such as wind and stream flow.

An engineer determining the capacity of a bridge, a process termed “rating,” is fortunate if the original design documents of the bridge are available, together with documentation of repairs, modifications and inspections. In that case, the design load can be compared with the original dimensions of the bridge and its components, including inspection records that indicate the actual condition of the components, and the bridge can be given a rating in terms of a common standard series of train loads. Absent the design documents for a bridge, an engineer should make a detailed inspection of every member of the bridge to record its actual dimensions, material, and condition.

Every train moving over a bridge causes forces to be developed in the components of the bridge. The magnitude of those forces in each component are determined by the weight carried on each wheel, the spacing of the wheels within the train, and associated effects, such as impact, rocking, and lateral forces. The effect of the actual load on a bridge can be associated with the effect of the rated load, and an engineer can determine if the proposed or actual loads are within the limits of the rated load, given any operating conditions placed on an actual load.

Several critical points are associated with making a proper determination of bridge capacities and loads. At a minimum, each track owner should take the following actions:

1. Ensure that a professional engineer competent in the field of railroad bridge engineering, or someone under his or her supervision, determines bridge capacity;

2. Maintain a record of the safe capacity of every bridge which carries its track;

3. Enforce a procedure that will ensure that its bridges are not loaded beyond their capacities; and

4. Ensure that regular comprehensive inspections are conducted.

Bridge ratings will change with time, and will seldom improve. Regular comprehensive inspections are vital to maintaining valid bridge ratings and to performing timely bridge maintenance and repairs.

The rating of timber trestles is a less exact process than the rating of steel and concrete bridges. Timber bridge components can vary widely in their composition, quality and condition. The inherent redundancy in timber trestles will partly compensate for a single sub-standard component, but the good parts which pick up more than their share of load from the weak member will degrade at a more rapid rate. It is essential that a weak timber member be repaired or replaced in a reasonable time; however, while it is still in place in the bridge, it and its surrounding members should be given extra attention with more frequent, detailed inspections.

Bridge Inspection

Railroad bridges are subjected to train loads and associated effects, as noted above. In addition, they are subjected to both natural and non-natural effects. Natural effects include decay, corrosion, deterioration of concrete and masonry, thermal expansion and contraction, freezing and thawing of water, floods, and growth of vegetation. Non-natural effects include impacts from vehicles and vessels, train derailments, vandalism and fires. All of these effects can severely and rapidly degrade the capacity of a bridge to safely carry its railroad traffic.

Railroad bridges also support much heavier loads in relation to their own weight (ratio of live load to dead load) than do highway bridges. All of these factors have led to a standard practice in the railroad industry to inspect each bridge carrying railroad tracks at a frequency of not less than once per year.

Bridge inspection, unlike the inspection of track, equipment and other railroad property, is a multi-level process. The inspector is a technician who should be able to reach all parts of the bridge to be inspected, detect indications of deterioration or other problems on the bridge, and accurately record and report them. Most railroad bridge inspection programs employ inspectors with these qualifications, but those inspectors are not expected to be able to perform the engineering calculations necessary to determine the safe capacity of a bridge. That function is performed by a competent engineer, working from basic design and historical records of the bridge and the reports of the inspector-technicians.

While the engineer needs complete and accurate information on the condition of the bridge from the inspector, the inspector can provide a much more comprehensive inspection if the engineer provides information back regarding any critical points or components on the bridge that might call for more intensive investigation or specialized inspection techniques. These items might be discovered in the bridge design documents, especially the so-called “stress sheets,” or by review of certain types of connections that have been prone to trouble on other bridges. This type of two-way communication can prove invaluable.

Protection of Train Operations

FRA did not address the issue of protection of train operations from potentially hazardous bridge conditions in the guidelines because FRA did not find it to be a problem at the time. Since then, however, FRA has discovered several instances where a person who was not fully qualified to determine the safety of a bridge was dispatched to resolve a report of trouble, and that person approved the bridge for continued service based on the criteria in the Federal Track Safety Standards, rather than a structural evaluation of the bridge. In a typical case, a track owner would have a railroad track inspector investigate a report from a train crew of rough track on a bridge. It is possible that during such an investigation, even a diligent track inspector would fail to find a deviation from the requirements of the Track Safety Standards for the class of track on the bridge, or, in the alternative, would find that the track could be brought into compliance with a temporary speed restriction. In this situation, it is likely that, after possibly placing a speed restriction, he would have returned the bridge to service while the structural condition that caused the track anomaly still existed. Without further attention, the anomaly would continue to deteriorate, until the bridge actually failed under load.

Recommended Action: FRA makes the following specific recommendations to owners of railroad track carried on one or more bridges, in order to prevent the deterioration of railroad bridges and reduce the risk of human casualties, environmental damage and disruption to the Nation's transportation system that would result from a catastrophic bridge failure.

(1) Inventory of Railroad Bridges. Every owner of track carried on one or more bridges should maintain an accurate inventory of those bridges. The inventory, or “bridge list,” should identify the location of the bridge, its configuration, type of construction, number of spans, span lengths, and all other information necessary to provide for management of the bridges.

(2) Regular Comprehensive Inspections. Every owner of track carried on a bridge should ensure that regular comprehensive inspections are conducted, as these are vital to maintaining valid bridge ratings and to performing timely bridge maintenance and repairs.

(3) Determination of Railroad Bridge Capacities and Loads. Several critical points are associated with making a proper determination of bridge capacities and loads. At a minimum, each track owner should take the following actions:

(a) Ensure that a professional engineer competent in the field of railroad bridge engineering, or someone under his or her supervision, determines bridge capacity;

(b) Maintain a record of the safe capacity of every bridge which carries its track; and

(c) Enforce a procedure that will ensure that its bridges are not loaded beyond their capacities.

(4) Railroad Bridge Inspection Procedures and Recordkeeping.

(a) Inspection frequency. Every bridge which carries railroad traffic should be inspected at least once per year. The level of detail and the inspection procedure should be appropriate to the configuration of the bridge, conditions found during previous inspections, and the nature of the railroad traffic moved over the bridge (car weights, train frequency and length, levels of passenger and hazardous materials traffic, and vulnerability of the bridge to damage).

(b) Inspection records. Every bridge inspection should be recorded, and the record of the inspection be available to the engineer who is responsible for the integrity of the bridge. The inspection record should show the date on which the inspection was actually performed, the precise identification of the bridge inspected, the items inspected and the condition of those items. Any inspection item that is found by the inspector to be a potential problem should be described in a narrative.

Many different systems are used to ascribe condition values to bridges and their components, but care should be taken that the inspection reports do not simply generate a number but, instead, an accurate description of the condition of the bridge components. It is appropriate to use a valuation system that serves to identify individual inspection reports that should be reviewed by the engineer or other engineering managers.

(c) Prescribing inspection procedures. The engineer responsible for the safety of a group of railroad bridges should prescribe the inspection procedures for those bridges. Bridges of a common configuration and no exceptional conditions may be considered as a group for a common procedure, but uncommon bridges, those with critical components and bridges which indicate possible deterioration that could affect their continued safety should be noted to the inspector. The inspector should be advised of any particular items of concern on the bridge, and any specific inspection procedure (frequency, detail and method) that is necessary to maintain the safety of the bridge.

(d) Review of inspection reports by a competent engineer. Bridge inspection reports should be reviewed by an engineer who is competent in the field of railroad bridge engineering. The engineer should determine whether the bridges are being inspected according to the applicable procedure and frequency, and will review any items noted by the inspector as exceptions. Often, the individual exceptions would not indicate a serious problem with a bridge, but when considered together by an engineer, they would show a more serious problem developing on the bridge.

(5) Protection of Train Operations. A bridge owner should designate qualified bridge inspectors or maintenance personnel to authorize the operation of trains on bridges following repairs, damage or indications of potential structural problems. Only a qualified person should be permitted to authorize train operation after such an occurrence.

Implementation of the FRA Bridge Safety Program

FRA has been conducting evaluations of railroad bridge management programs since the 1980's, before the Bridge Safety Policy was first issued. The Policy indicates that its guidelines will be the basis for FRA's evaluation of bridge management. This Safety Advisory essentially amplifies and clarifies the criteria included in the Policy guidelines. The recommendations included in this Safety Advisory will be reviewed by FRA personnel when conducting evaluations of railroad bridge management. The same criteria, together with other risk factors, will be considered by FRA when selecting small railroads for further evaluation. FRA will maintain on-going evaluations on the larger railroads and passenger carriers.

FRA has been able to adhere to its policy of not issuing specific regulations governing bridge management, bridge conditions and bridge capacities. If the continuing evaluations show that the railroad industry is essentially adhering to the principles of good engineering and the provisions of this Safety Advisory, and also provided that no significant train accidents are caused by the structural failure of a railroad bridge, FRA intends to continue with this non-regulatory policy.

Owners of track carried on one or more railroad bridges are encouraged to voluntarily take action in accordance with these recommendations. If circumstances so warrant, FRA reserves the authority to take other corrective action, including: issuing an emergency order to restrict operations over a railroad bridge if necessary to protect public safety, modifying this Safety Advisory 2007-03, issuing additional safety advisories, taking regulatory action, or taking other appropriate action necessary to ensure the highest level of safety on the Nation's railroads.