Mismatched Braking Systems on Metrolink Trains Presage Disaster
On October 1, 2015, I wrote about Southern California regional rail passenger carrier Metrolink’s decision to lease forty Burlington Northern Santa Fe (BNSF) freight locomotives. In September 2015, the National Transportation Safety Board (NTSB) had notified Metrolink that serious safety deficiencies existed on their Hyundai-Rotem cabcars. The deficiencies involved the February 24, 2015 Oxnard Metrolink collision that injured scores of passengers and took the life of Metrolink Senior Engineer Glenn Steele.
In Oxnard, the “pilot”, a blade that rides just above track level at the front of each cabcar, had failed in a collision with the work truck. As the Metrolink cabcar swept over the truck, the pilot detached and disappeared into the wreckage. Speculation was strong that the detached pilot had contributed to the derailment of the cabcar and the several coaches riding behind it.
Information from NTSB to Metrolink and then via Dan Weikel of the L.A. Times to the public pointed to structural failure. The steel in both the pilot and its support struts was too porous to withstand the load of the Oxnard collision. In addition, welds between the struts and the pilot showed gaps or porosity that weakened the entire assembly. Confronted with an obvious public safety hazard, Metrolink made a snap decision to place a locomotive at each end of every train set.
On December 31, 2015, I rode on one of the first “double-ender” Metrolink trains traveling from Chatsworth to Los Angeles Union Station (LAUS). It was quite a sight to see a 420,000 lb. BNSF locomotive pulling a five-coach train back toward LAUS. The conductor on the train told me that both the BNSF locomotive and the Metrolink locomotive at the other end provided motive power while operating in either direction.
Citing available statistics for the weight of each locomotive and various Metrolink coaches, I wrote in October 2015, “Riding on four axles, current Metrolink diesel locomotives weigh 280,000 lb. At over 420,000 lb., the six-axle BNSF freight locomotives are fifty percent heavier. A 2015 five-car Metrolink train weighed approximately 460,000 lb. By adding a freight locomotive at one end, each "heavy iron" BNSF train set will weigh 880,000 lb., an increase of ninety-one percent.”
The sole purpose of adding the BNSF locomotives was to assure that any motor vehicle encountered on the tracks would be obliterated. Still unclear was how the braking systems on a double-ender would perform while stopping a 440-ton train. I reflected my concern by titling my October 1, 2015 article, “Metrolink Plans for Live Brake-Tests of BNSF ‘Heavy Iron’ Train-Sets on Commuter Tracks”.
At the Chatsworth Station on March 15, 2016, I discovered the answer to my questions about “heavy iron” and braking safety. The answer is that Metrolink double-ender train sets appear to be unsafe. The newly configured Metrolink train sets are a hodgepodge of engines and coaches. The BNSF freight locomotives are better suited to dynamic (engine) braking, rather than using their pneumatic braking system. Each train set also includes an ill-maintained Metrolink locomotive pushing from the rear. In normal “stop and go” usage between Metrolink stations, both locomotives rely on their pneumatic braking systems.
In between the two locomotives are the heavy, steel-sheathed Hyundai-Rotem coaches and lighter monocoque aluminum Bombardier Bi-level coaches. While both locomotives rely on pneumatic “brake blocks” similar to old-fashioned brake shoes, the Hyundai-Rotem coaches employ outboard disk brakes. Depending on their state of refurbishment, the Bombardier Bi-level coaches appear to utilize various combinations of disk brake and block brake systems.
Each locomotive and coach in any train set connects to its mates with high-pressure air hoses. When the engineer applies the pneumatic brakes, every block or disk in the system activates, creating friction and heat, thus slowing the train. With such diversity in ages and types of braking systems, each wheel-truck may receive a different level of braking power, leading to different stress and patterns of wear.
By Metrolink’s own admission, the agency does not conduct major preventative maintenance or periodic overhauls of its locomotive fleet. The agency prefers, instead, to run its locomotives until breakdown, and then conduct maintenance sufficient only to get a broken locomotive back in service. While allowing its current fleet of locomotives to self-destruct on the tracks, Metrolink is spending $338 Million in taxpayer money on new "Tier-4" locomotives. Metrolink may or may not conduct preventative maintenance on its locomotive braking systems. Since Metrolink does not publish information regarding maintenance of braking systems, no one knows.
In addition to aging and mismatched locomotives, Bombardier Bi-level coaches, are included in virtually every Metrolink train set. With over one million miles of service each, wheels with flat spots are a common problem on the Bombardier Bi-level coaches. On those coaches, some wheel-trucks include retrofits to disk brakes while others appear to utilize the older brake-block systems. With so many mismatches and deficiencies elsewhere, the relatively small disk brakes on the newer Hyundai-Rotem coaches and cabcars absorb much of the total braking load.
With all of the mismatched coaches and locomotives, the easiest way to detect brake wear on a Metrolink train is to inspect the Hyundai-Rotem brake rotors, which ride outboard of the wheels. While conducting a casual inspection of the Hyundai-Rotem brakes, I was shocked to see that every visible brake rotor displayed thermal-fatigue cracks (heat checking) radiating from the hub towards the outside edges of the rotors.
I am not a metallurgical engineer, but I have driven many vehicles that include disk brakes. The Hyundai-Rotem disk brakes are larger and feature pneumatic actuation. Otherwise, automotive disk brakes are quite similar to the Hyundai-Rotem type. After an automotive brake inspection, no competent mechanic would allow me to drive away with extensive thermal damage evident on my rotors. With the heat-induced cracks that I recently discovered on Hyundai-Rotem brake rotors, why are those damaged safety components still rolling on Metrolink coaches today? As Metrolink knows from the deadly Glendale (2005), Chatsworth (2008) and Oxnard (2015) collisions, greater attention to safety might prevent the next Metrolink rail disaster.