How decades-old train design created an ongoing fire risk for passengers

NTSB calls for suspension of Silverliner IV trains over immediate fire risk

Five fires in eight months prompt federal intervention

The National Transportation Safety Board (NTSB) has called on the Southeastern Pennsylvania Transportation Authority (SEPTA) to immediately suspend its fleet of Silverliner IV railcars after five electrical fires in 2025.

The federal agency concluded that the design of the nearly 50-year-old Silverliner IV trains, combined with maintenance and operational shortcomings, represents “an immediate and unacceptable safety risk” to passengers and crews.

The NTSB’s urgent recommendations follow its investigation into a series of incidents beginning with a February 6 fire in Ridley Park, Pennsylvania, which destroyed one of the six-car train’s lead railcars.

Four subsequent fires occurred between June and September in Levittown, Paoli, Fort Washington and Philadelphia.

Each involved electrical failures linked to propulsion, traction or braking systems, and in several cases, fires spread from the undercarriage into occupied compartments.

The NTSB said that, despite repeated warnings and operational adjustments, SEPTA continued to operate defective trains, placing passengers and staff at risk.

Electrical failures repeatedly triggered undercarriage and roof fires

Ridley Park fire caused by overheating propulsion components

On 6 February, the lead railcar of train 3223 caught fire shortly after departing Crum Lynne Station in Ridley Park.

About 325 passengers and four crew were on board.

Two hours earlier, the operator had reported sluggish acceleration and a fault light.

Maintenance staff inspected the train but left it in service.

Shortly after, the operator noticed smoke and stopped the train.

The fire spread from the undercarriage to the passenger compartment, igniting seats, wall panels and the roof.

Four passengers sustained minor injuries.

Preliminary analysis determined that the fire began when electrical components in the propulsion system overheated.

Levittown fire traced to dynamic brake malfunction

On 3 June, the rear railcar of train 7206 caught fire at Levittown Station.

Roughly 150 passengers were evacuated without injury.

Investigators found that the fire originated when a cam controller pilot motor failed and a dynamic braking pressure switch was miscalibrated, causing the train’s braking system to remain stuck in dynamic braking mode.

This led to overheating of resistor grids, which ignited a fiberglass roof duct.

Paoli and Fort Washington incidents followed same pattern

On 22 July, a similar incident occurred at Paoli Station when train 3553 lost power.

Crew members encountered smoke while resetting the fault light and evacuated 14 passengers.

The conductor was treated for smoke inhalation.

As in Ridley Park, the fire began in the undercarriage and spread inside the railcar.

On 23 September, another fire broke out aboard train 3592 near Fort Washington Station.

That train used the same railcar previously damaged in the Levittown fire.

Although repairs had been completed, investigators found that electrical components near the resistor banks again ignited, likely as a result of earlier repair work.

All 350 passengers were evacuated without injury.

Philadelphia incident exposes ongoing safety gap

Just two days later, on 25 September, the fifth incident occurred when train 705 caught fire at Gravers Station in Philadelphia.

The train had been operating with a fault light illuminated since the previous day.

Multiple crews had ignored the fault, allowing the train to remain in service.

The fire began on a traction motor under the railcar and was extinguished using a handheld extinguisher.

The NTSB said this incident illustrated the breakdown between SEPTA’s proposed safety measures and their practical enforcement.

Design and regulatory failures at the core of the fire risk

Silverliner IV design predates modern safety standards

The Silverliner IV fleet entered service between 1974 and 1976 under the Reading Company, before being absorbed by Conrail and later transferred to SEPTA in 1983.

As of 2025, 225 of SEPTA’s 390 passenger railcars are Silverliner IVs.

The NTSB noted that the trains have never undergone refurbishment and were built decades before federal fire safety standards were introduced in 1999.

Under Title 49 Code of Federal Regulations (CFR) Part 238, modern railcars must be able to contain fires for a minimum of 15 minutes—twice the time required to stop safely and evacuate.

The regulation also requires the separation of ignition sources and energy systems from passenger compartments.

Preliminary evidence from the Ridley Park and Paoli fires shows that Silverliner IV cars failed this containment standard, allowing flames to enter occupied spaces.

Lack of diagnostic systems limits operator awareness

The NTSB found that the Silverliner IV’s electrical system includes only a single fault light to indicate any issue, regardless of type or severity.

Modern railcars use feedback systems to distinguish between propulsion, braking and auxiliary electrical faults.

By continuing to operate trains with illuminated fault lights or known defects, SEPTA exposed passengers to escalating risks of electrical fire, the report said.

The NTSB concluded that keeping defective railcars in service magnified the danger inherent in the fleet’s outdated design.

NTSB questions SEPTA’s risk mitigation and response plans

Early efforts failed to prevent recurrence of fires

Following the first three incidents, SEPTA issued a memo on 25 July directing staff to remove any Silverliner IV from service if electrical faults recurred, if dynamic brakes malfunctioned, or if smoke or burning odours were detected.

The authority also pledged a one-time inspection of high-voltage cables and resistor banks and began revising fault-reporting forms.

In August, SEPTA submitted a mitigation plan to the Federal Railroad Administration outlining further steps, including:

Reducing use of Silverliner IV trains, improving radio communication, replacing fiberglass roof ducts with stainless steel, testing traction motor cables, installing support brackets, and hiring a contractor to investigate root causes of the fires.

It also committed to installing thermal protection circuits to cut power automatically during overheating events.

Ongoing fires show systemic organisational failures

Despite these measures, two further fires occurred in September.

The NTSB said both incidents show that SEPTA’s new rules were not enforced and that underlying organisational factors prevented meaningful risk reduction.

It found that crews continued operating trains with known electrical problems, inspection schedules failed to prevent repeat faults, and repairs did not address the underlying design vulnerabilities.

The agency said: “The recurrence of fires despite SEPTA’s attempted operational, maintenance, and engineering changes is consistent with organizational factors preventing proposed risk mitigations from being effectively deployed.”

Investigators call for suspension and fleet replacement

The NTSB concluded that SEPTA’s proposed measures are only short-term and do not address the root design weaknesses of the Silverliner IV fleet.

It said that even successful implementation of maintenance changes cannot substitute for structural upgrades or compliance with federal fire standards.

The agency issued three urgent recommendations:

Suspend operation of all Silverliner IV railcars until the root causes of the fires are known and corrective actions are in place.

Develop and fund an accelerated retrofit or replacement programme that brings the fleet into compliance with Title 49 CFR Part 238.

Implement ongoing monitoring to verify that any risk-mitigation measures remain effective, with provisions for immediate withdrawal of the fleet if fires recur.

Federal standards and next steps for passenger rail safety

Compliance required under Title 49 CFR Part 238

The NTSB said that future compliance for SEPTA will require a full redesign or replacement of the Silverliner IV fleet to meet 21st-century fire safety standards.

It emphasised that 49 CFR Part 238 sets mandatory benchmarks for structural fire containment and requires material selection and layout designed to minimise ignition and smoke spread.

The report noted that these measures have been standard for new railcars since 2002, but the Silverliner IV’s design remains exempt due to its age.

The NTSB said that the ongoing investigation will continue to analyse the role of organisational decision-making, crew communication, and failure to act on fault indications in allowing defective railcars to remain in service.

It also reaffirmed that its safety recommendations do not assign fault or liability, but are intended solely to prevent further accidents and loss of life.

Relevance for fire and safety professionals

The NTSB’s investigation into the Silverliner IV fires holds direct implications for professionals working in transport safety, electrical engineering and emergency management.

The findings illustrate how ageing transport systems without fire containment or fault isolation measures can expose passengers to electrical ignition hazards.

For engineers and maintenance professionals, the report provides a detailed example of cascading system failure, where missing diagnostic feedback, weak enforcement of fault policies, and design-era limitations combine to defeat safety controls.

It highlights the regulatory requirement for thermal protection circuits and material fire-resistance standards under Title 49 CFR Part 238, offering a technical benchmark for those overseeing retrofit projects or safety audits in other transport fleets.

Emergency response planners, risk assessors and incident investigators may draw lessons from the evacuation challenges described in the five incidents, particularly the Ridley Park and Paoli fires where flames entered passenger areas.

More broadly, the case demonstrates the operational risks of deferred asset replacement and the need for continuous monitoring of fleet safety performance in public transport operations.

This article was informed by information from the following source: The National Transportation Safety Board (NTSB)