06 September 2026

SP 1941 Tunnel 26 Accident - Factors Beyond the ICC Report

Blame the dead guy?!

This is the final look at the Southern Pacific Tunnel 26 accident of 19 November 1941, involving the Extra 4193 West.

Readers probably noticed that the official accident investigation by the Interstate Commerce Commission did not consider as many parameters as a modern multi-disciplinary accident investigation would today. 

Essentially, the report said the accident occurred because: 

1) The train stalled in the tunnel. 
2) No one turned off the oil supply after this happened. 

My post which includes the ICC's report can be found here:


All of the previous Southern Pacific-related posts can be found
by pressing the Short Subjects 02 radio button (in the top banner)
and scrolling down alphabetically until your reach the 'SP ... ' items.

*  *  *

The engineer and the young fireman (the 'engine crew' responsible for the oil supply) both died in the accident. The ICC investigators provide a neat, factual conclusion. It places no responsibility on the railroad, anyone in company management, or anyone who is alive.

In an earlier post, I tried to describe the economic boom being experienced in California in 1941 ... created by the 'wartime economy' which immediately preceded the US entry in World War 2. 

We do not know if this boom contributed to the loss of experienced railroad workers to more stable and 'family friendly', well-paying industrial work ... or if increased traffic demand resulted in a wave of new employee hiring. 

The short period the fireman had been employed is cited in the investigation. After unpaid student trips with practical instruction (of variable quality) in the cab of a working engine ... and self-study (no formal classroom instruction) ... the fireman would have been judged ready to begin work under the normal supervision of an engineer. 

The ICC report does not address the issue of new employee training.

... In the 1940s, is it likely that a newly-hired fireman would be empowered - during any of this casual training - to 'shut down' the locomotive of his own volition if he had identified a safety emergency?

*  *  *

This post will look at five factors:

1. Train crew members.
2. Engine crew members.
3. The Extra 4193 West and the timetable.
4. The role played by maintenance of way equipment.
5. Decision making, task saturation and situational awareness.

*  *  *

We do not know if there were any professional consequences for the four surviving crew members. 

Similarly, we do not know if the railroad officials supervising these employees, or other aspects of railroad operations, were subject to company sanctions. 

We do not know how the survivors' lives were affected by this tragedy.

*  *  *

1. Train Crew Members (4)

The conductor is responsible for conducting the movement over the line. On this train, there was a brakeman on the engine and two brakemen in the caboose with the conductor. Traditionally, the conductor would work collegially with the engineer - rather than trying to 'pull rank' on general decision-making.

With the advent of more powerful motive power and 100-car trains, this traditional arrangement breaks down. In 1941, there was no end-to-end radio communication on SP trains. How could a conductor instruct or confer with the engineer? The crew in the caboose could only give physical signals along the side of the train to relay instructions - assuming the engine crew was looking back to see them at precisely that moment.

... Or ... the conductor could 'pull the air' if there was a rules-based justification for it. The act of slamming on the emergency brakes - if not reasonable in the engineer's eyes - would send a shockwave through the local engineer community on the same day it happened. Only a micro-managing conductor who didn't respect engineers would put the whole train into emergency! 

(In fact, I think I remember seeing old caboose brake valves which allowed a range of increasing brake pipe reductions. However, I think it was necessary to stop the train before any graduated brake pipe reduction by the conductor could be reversed.) 

In any case, there was a strong social disincentive to using the conductor's valve to 'communicate'. 

Consequently ...

In most cases, the engineer had all the responsibility of ... supervising the fireman; protecting the company's valuable capital investment in the motive power (and steam locomotives were very labour-intensive to operate); ensuring the movement follows all the rules and speed limits; do all the 'driving'; and thus take sole responsibility for all of the rolling stock and its contents for most of the trip.

To oversimplify: With a 100-car train in the 1940s, the conductor is just along as a passenger who handles company paperwork, and who leads and supervises the train crew when the train has stopped to conduct switching moves.

As an example: This conductor was not aware of the conditions at the locomotive inside Tunnel 26. Consequently a tailend brakeman was sent toward the headend with a verbal movement directive for the engineer. This messenger died from the lack of oxygen just a few car-lengths into his long trip in darkness to the headend.

2. Engine Crew Members (2 + 1 student)

To become an engineer, one must first work as a fireman. A fireman's work leaves little room for error. A fireman's mistake which the engineer does not notice can precipitate a wide variety of consequences: from merely expensive for the company ... to catastrophic with the loss of life.

In addition to the 24-year-old fireman with 2 months' experience, this engineer had a second 24-year-old student fireman in his cab. 

A fireman whose skills are not fully developed can undermine the outcomes the company expects of the engineer. The 'in real time' supervising railroad official (i.e. the dispatcher) expects the train to get over a busy subdivision in the normal time. It is up to the engineer to achieve this - new fireman or not.

At some point or another, the engineer on the Extra 4193 West had to: think of ... monitor ... coach ... or compensate for ... two inexperienced firemen working on his engine.

Further adding to the engineer's cognitive workload, the experienced brakeman on the headend provided unsolicited input en route on the need to stop and repair a faulty cylinder cock observed on his side of the engine. The engineer declined to do this, citing the delay this repair would cause.

ICC report: "According to the statement of the student fireman who was on the engine the engineer experienced difficulty with the throttle throughout the trip."

It is unclear whether the engineer's problems with throttle control were the result of: 
  • A basic ergonomic failing of the cab design and the throttle lever.
  • A physical or medical problem the engineer had.
  • A defect the company shop had not repaired on this essential control. 
The throttle control problems contributed significantly to the loss-of-life accident, according to the ICC investigation.

*  *  *

The Assigned Crew

Considering this train - an extra freight running at night - we may conclude that these crew members are not a 'regular crew'. That is, they are not regularly assigned to work together on a particular job at the same time each day. 

They are working out of the Los Angeles 'hub' - from which radiate many subdivisions, and industrial and switching work assignments. Perhaps only the headend brakeman, conductor and engineer (all with years of service) know each other well. 

The fireman and the tailend brakemen may have been called from their spareboards ... where low-seniority workers waited for a call to work: 24 hours per day, 7 days a week.


It is only in modern investigations that the following foundation for performance is documented: 

That each member of the crew is fit, rested and qualified for duty. None of this was considered in the ICC report. 

*  *  *

3. The Extra 4193 West and the Timetable
  • Below, is the timetable in force at the time of the accident. 
  • Traffic on the Ventura Subdivision is controlled by timetable, train orders and an automatic block system.
  • Extra 4193 West is 96 cars + caboose in length, 3550 tons (the maximum rating for the engine here was 3650 tons).
  • It departs from Los Angeles yard at mileage 479.7 at 2315hr on 18 November 1941.
  • The siding capacities and subdivision mileages are shown on Page 2, below. Page 3 is supplied only for completeness and to show that there are no scheduled westbound freights which could help us calculate the expected progress our extra would make over the subdivision. While Train No 373, the Coast Merchandise Westbound, originates at LA Yard, it transports LCL freight, fresh produce and other perishables. Special rolling stock allows it to travel at passenger train speeds.
  • We do not know anything about the traffic on the railroad that night. The only thing that I can assume is that Train 812 - a Second Class eastbound train - is running, and that it is on time. 
  • As the Extra 4193 West must clear for Train 812, the responsibility for calculating and organizing this meet falls on the shoulders of the engineer. The conductor cannot participate collegially in this decision from the isolation of the caboose, 100 cars back. 

from: The employee timetable collection of the California State Railroad Museum, Sacramento. archive.org
https://archive.org/details/cscrm_2021_02_001478/mode/1up

from: The employee timetable collection of the California State Railroad Museum, Sacramento. archive.org
https://archive.org/details/cscrm_2021_02_001478/mode/1up

*  *  *

The Engineer Calculates the Meet

screencaps from: Southern Pacific employee timetable 183, Los Angeles Division, 8 July 1945. archive.org
https://archive.org/details/cscrm_2021_02_001553/page/n19/mode/1up

  • The map above is identical to the map published with the 1941 timetable. 
  • My yellow dots and labels show the route. The times are from the ICC report.
  • The red dot is the accident location.
  • The red labels show the expected scheduled progress of Train 812 against Extra 4193 West.
  • The three green dots show the only sidings in which the Extra 4193 West will fit.
  • My guess is that Moorpark would be the chosen location to clear ... if the extra makes normal progress.
  • Once the extra passes Santa Susana siding, the engineer is committed to clearing at Moorpark. Stopping at Santa Susana would probably result in the conductor 'collegially' stomping up the ballast and demanding to know why they are waiting for an hour on a siding. 
  • Completely clearing at Moorpark would typically be 5 minutes before the 0135hr scheduled time of No 812. This means the extra is stopped in the siding, with its headlight off, and with the switch behind the caboose lined and locked for the passage of No 812. No 812 will be governed by the ABS signals indicating track occupancy (if the Extra has not cleared) as it approaches the siding.
  • While this meet is a laboured calculation for me, it would be a routine decision for an experienced engineer. 
  • We cannot know if aiming for the target of Moorpark influenced the engineer's decision not to stop to repair the cylinder cock. 
  • Similarly, we cannot know that the cylinder cock defect was definitive in the stalling of the train in Tunnel 26.

I would be very surprised if only these two trains were operating that night. Given the increased demand to move 'wartime' traffic, it seems much more likely that additional extra movements ... and/or routine dispatcher modifications to the schedule through train orders ... were added to the engineer's mental model of the subdivision traffic that night.


*  *  *

4. The role played by maintenance of way equipment.

In the footnotes at the back of the timetable is this text.


from: The employee timetable collection of the California State Railroad Museum, Sacramento. archive.org
https://archive.org/details/cscrm_2021_02_001478/mode/1up

Automatic mechanical flange (rail) lubricators were intended to decrease friction between the wheel flanges and the 'gauge face' of the rails on curves. 

As a maintenance of way device, they decreased rail wear - reducing the familiar flange-squealing sound. They could also help prevent derailments on curves when gauge face friction was so great that a wheel would climb over the rail and cause a derailment. 

Below, is text from a 300-page book published by Imperial Oil/Esso on all aspects of railroad lubricants, circa 1950. (Imperial Oil/Esso was a Canadian subsidiary of the former Standard Oil - Exxon.)

from: Railway Lubrication; circa 1950; Imperial Oil.

The design of the flange lubricators used by the SP in 1941 was probably of a less efficient, earlier design from the 1930s. 

Even in the 1970s and 1980s these devices always seemed to be sitting in a black wasteland of fugitive grease. The deep grease reservoir in the diagram (above) suggests that maintenance of the device is not going to be a daily task during which the section gang comes by with a roll of paper towels and wipes away any grease which has fouled the top of the rail.

Continuing with flange-rail friction ... the 4193 did not need any blind driving wheels (i.e. none were flangeless) because its two eight-driving-wheel 'engines', were articulated to move independently of each other. Among the driving wheels, some axles were also designed to accept lateral motion. This engine probably cornered like it was on rails. 

Below is a wonderfully helpful section of a 'track profile' from Multimodalways (linked below). It is from 1992. However, the mileage of Chatsworth 445.5 is identical to the 1941 employee timetable (numbered from Santa Barbara) so the curves and tunnels can be assumed to have the same mileages as well.

I have added polka dots to make it festive. 

 
from: Multimodalways - SP Lawrence-Burbank Jct Track Chart 1992 (PDF)
https://www.multimodalways.org/archives/rrs/SP/SP%20Track%20Charts/SP%20Track%20Charts.html

  • On the line near the top with all the labels, you can see Tunnel 26 labelled, then 27, 28 and Chatsworth at 445.5 .  
  • The next line down is the track mileage graduated in tenths of miles, i.e. 440, 440.1, 440.2 etc., type of rail, ballast, etc.
  • The bottom line shows gradient (and/or ruling grade), coming eastbound from Santa Barbara ... so minus 1.0 ( ... or +1.0 % for the 4193 as it approaches Tunnel 26 westbound, purple dot).
  • The line above gradient shows curvature. My blue dots show the two distinctive ~90 degree curves east of the tunnel are identified as 223 and 224. You'll notice that they straddle very short Tunnel 28.
  • Referring to the timetable note above: lubricators are at 442.7, 443.7 . These are marked with red dots on the track profile.

At the top of Page 6 of the ICC report, it says: 

"When the engine was at a point about 5,000 feet east of the east portal of tunnel No. 26 the engine slipped and the train stalled. After the slack was taken twice the train proceeded and when the engine entered the tunnel the speed was between 10 and 12 miles per hour. At a point 3,899 feet west of the east portal, or approximately half way through the tunnel, the engine again slipped and the train stalled.

... As the engine slipped and stopped inside Tunnel 26 ... the train slack ran in from inertia ... and back out from gravity ... and when the runout of slack reached back 75 cars to the steel gondola loaded with steel ... it broke its knuckle and the train brakes went into emergency. This locked up the wheels on the whole train. This emergency brake application marked the beginning of the fatal accident.

*  *  *

If you notice the mileage and location of the first lubricator the engine passed over (the red dot at the right, above) ... "5000 feet from the portal" is consistent with a point reached shortly after the engine ran over the first lubricator. The engine slipped here twice.

I have tried to accurately transcribe the two red dots on the track profile above to a current GoogleMaps view of this track section as it appears today. 


The 4193 passed over the second lubricator as it was entering Tunnel 26. 

But if the 4193 slipped and the train stalled at the first lubricator, why didn't the train stall at the second lubricator just outside the tunnel?

And how was the 4193 able, after passing that second lubricator, to pull the whole train onto the 1% grade inside Tunnel 26 before slipping and stopping?

(The ICC diagram of Tunnel 26 gradient appears below.)


Having slipped ... stalled ... taken slack twice in order to restart the train ... knowing he was approaching a second lubricator ... and knowing he would be running his train up a 1% grade ... while pulling 3550.5 tons (of a rated 3650 tons for the engine in this territory) ... the engineer would perhaps be taking no chances with traction and he might be sanding heavily


As we saw in a recent post about pre-trip locomotive inspection, taking slack, cylinder cocks and sanding ... 

from: Locomotive Management; AB Carson; 1928, 1937; International Textbook Co.

I have read many books about railroad operating procedures but I had never encountered this paradoxical side effect of sanding before. 

Since the long-ago adoption of diesel-electric power, with its high tractive effort and good adhesion at low speed, it seems possible this 'stalling because of sand' might be a 'lost railroad phenomenon'. Given how frictionless shaped steel wheels on steel rails are, this unexpected effect of sanding is yet another fascinating aspect of wheel-rail physical science. 

We will never know whether the flange lubricators and reactive sanding were significant factors in this accident. 

The ICC investigators were extremely diligent in their review of the local physical forensics inside the tunnel: measuring and locating the roof damage from the exhaust and safety valve discharge ... and the rail burns from slipping ... to recreate the engine's movement within Tunnel 26. 

However, they made absolutely no mention of the two lubricators' locations, state of repair, or functioning at all. 

They did not analyze the train dynamics and traction at the point of the first slipping (twice) and gathering of slack (twice) at/near the first lubricator.

*  *  *

Train Handling

When knuckles break and trains stall on grades, investigations have typically looked at the performance of the engineer and his 'train handling'. The 75th car of 96 was a gondola car constructed of steel which was loaded with steel. It was a slack runout which broke the knuckle on this car and precipitated the accident.

The conductor denied that there had been any problem with harsh slack action in the train up to that point. The marshaling of loads/empties in the train is not discussed in the ICC report.

The investigators suggest that because the independent brake was found in the applied position after the accident, this had probably caused the slack runout and the breaking of the knuckle on the steel gondola.

*  *

Those Onboard the Engine

The accounts given by the participants to newspapers immediately - during the first 24-48 hours after the accident - are not always the same as the actions and accounts which were taken under oath and included in the ICC report.

Speaking from his hospital bed, the student fireman stated: 

"When the engine stalled I went out one side of the cab with [the brakeman] while the other two climbed out the other side."
 
...  then ... his 5-word gift to the journalists: "like being lost in hell" ... then ...

"[The brakeman] and I made our way to the end of the tunnel - and after we got our breath we went back in to find out what happened to the engineer and the fireman." 

Prescott Evening Courier (Arizona), 19 November 1941.

... Having struggled in the dark for 3529 feet to reach the west portal, the brakeman and student fireman had narrowly escaped death. At the upper (west) portal of the tunnel, where most of the gases would naturally flow and accumulate, no reasonable person would expect them to retrace their steps back into the tunnel.

Standard Code of the AAR, 1940, General Rules, Rule L:
"In case of danger to the Company's property employe[e]s must unite to protect it.

The headend brakeman and the engineer probably knew each other from their years of service. In reading the newspaper accounts of the accident, I have always wondered about the terms on which these two veterans parted ...

Nowhere is there any account that the engineer told the brakeman and student to leave the equipment to save themselves.

If the brakeman and student exited one side of the cab and the engineer and fireman the other, was the engineer aware that the brakeman had made the bold and appropriate decision to save his life and that of the student's by abandoning the train?

*  *  *

On these engines, I believe the pull-handle-cable-linkage to release the spring-loaded oil cut-off inside the tender was always located on the backhead cab wall - that is, behind the engineer and fireman. It was located here so either member of the engine crew could easily reach it to cut the fuel when any emergency required a quick response. The ICC report stated that it had not been triggered, but that it worked flawlessly during the investigation.

What are the possible reasons why the fuel was not turned off in this manner?


5. Decision making, task saturation and situational awareness.

Earlier, I suggested that the fireman (with two months' experience) would not consider it being within the realm of his authority to decide that the engine must be shut down.

The ICC report notes the failure to move the fireman's oil regulator valve to the 'drifting' (i.e. like 'idle') setting ... or to close the oil regulator valve entirely. 

However, as I understand it, closing the fireman's oil regulator valve would shut the engine (fire) down ... having the same effect as if the fireman had actuated the emergency cutoff via the cable leading to the tender valve.

Having a '100-car freight train going into emergency in the centre of Tunnel 26' would not have been covered in the fireman's training materials or his trial trip instruction. When this happened, he would look to the engineer ... in order to follow his instructions in this emergency situation. 

*  *  *

It was the engineer's fault.

... That is the conclusion the ICC investigation leaves us with. 

I think the engineer did not turn off the oil supply using the cable-linked tender valve 
because he could not.

The reasons might include:

A) He had a medical crisis (eg. a heart attack) before he could act.

B) He was injured in the cab or as he exited the cab (eg. he was scalded, or he fell from the cab ladder, or he fell into one of the tunnel drains). 

C) He was trying to solve the problem in a 'conventional railroad way' - which would cause the least delay to his train and to the traffic on the railroad. 

He may not expect that the young fireman (or the student) has left the oil regulator valve in a low 'working engine' fire setting which is creating choking smoke. This is because the 'working fire' is not being drafted by the exhaust of a working engine. 

He expects he will be 'examined' by management over his train-handling, so he is working efficiently to add as little delay as possible. With the brakeman unable to reach the tender to cut the power off the train, it is up to him to wait out the safety valve steam, uncouple the engine, and run it out of the tunnel.

The 'correct' answer from the safety of a 2026 blog post is 'to stop the fire to preserve life' ... and get the engine out of the tunnel and out of the way (for the moment) by using the steam pressure in the boiler. But ...

... Perhaps the engineer was well aware that everything on an oil-fired engine needs high pressure steam. The tender tank heater to keep the heavy bunker oil flowing, the oil superheater to get it to burning temperature, the atomizer to break the heavy oil into fine a mist which can burn, the blower to draft the fire of a stationary locomotive, the injector to keep the boiler filled with water. 

... If the fire was extinguished and boiler steam was consumed to run the engine out of the tunnel, an extended delay might occur because remedial efforts would have to be made to re-light the stubborn heavy oil with diminished steam pressure. Next, would come the work to nurse the boiler back to operating temperature to produce adequate quantities of steam.

... The ICC report suggests cutting the oil supply (they are as smart as a 2026 blogger) ... or leaving the oil regulator in the drifting setting. However, the ICC offers no estimate on life expectancy for the workers in the small air volume of the tunnel even with this lighter fire setting. The reason for the emergency air brake application would have to be found and corrected while the fire burned away inside the confined area of the tunnel with the crew members present.

Speaking of the emergency air brake application. As far as the headend knows, uncoupling the engine would leave all 96 cars at rest on a 1% grade. If the air bleeds off and the tailend crew did not take the precaution of applying an adequate number of handbrakes, an eastbound runaway of the entire train might occur.

D) Task Saturation. I won't drag you through the list again. But see if you can imagine and/or recall all the information, calculations and functions the engineer has had to consider and perform ... from his usual pre-trip responsibilities as an engineer ... up to this point ... one hour (37 miles) into his 108-mile workday.

Hi-lites: After leaving Los Angeles yard, he's had two inexperienced fireman working on his engine. He's had problems with the throttle, traction, and with stalling the train (three times). He is aware of the probability of discipline by company management because of the situation he now finds himself in ... in Tunnel 26. He can't account for the whereabouts of the brakeman and the student who were in his cab. He's trying to imagine the best way to handle whichever mystery problem has caused the emergency brake application. He has no idea what the tailend crew is doing. 


E) Loss of Situational Awareness. Because of the engineer's task saturation with 'conventional railroad procedures' it is impossible for him to recognize that in only a few minutes he and his fireman will become unconscious and then die. That is why he does not extinguish the fire.


*  *  *

The End

*  *  *

By way of being constructive and preventing this type of occurrence from happening again in 1941, I would look at the following issues:

1. While the ICC details all of the engineer's cab control settings as they were found ... and shows that there was adequate sand ... and that the emergency oil cutoff worked ... and the impractical and irrelevant observation that no respirators were signed out of the shop in Los Angeles - i.e. a full hood with a hose coming out the top which attaches to the air brake system. Their investigation DOES NOT comment on the proper functioning of the throttle lever. Was there a defect which the shop left uncorrected? The report DOES NOT explain (if it might account for a loss of traction in Tunnel 26) WHY an engine is leaving the shop with an constantly open, malfunctioning cylinder cock

2. The ICC offers a short sentence in recognition of the fact that the fireman "involved had but little experience". However, it makes no pronouncement on the training of that fireman. Should new firemen be trained that crew safety is paramount and that, in the event of an emergency in a long tunnel, the FIRST CONSIDERATION MUST BE to ask the engineer: 'Should the oil regulator valve be closed or should the emergency oil cutoff be engaged until the reason for the emergency brake application is known?'

3. The ICC does not comment on how having an inexperienced fireman AND a student fireman in the cab at the same time affects the efficiency and safety of locomotive operations. It does not address how this might create unnecessary distractions for the engineer. 

4. The ICC notes the location of the first loss of traction, wheel slip and train stalling (twice at that location). It does not mention the fact that this loss of traction was at the site of a flange lubricator. It does not record the STATE OF MAINTENANCE of that flange lubricator, or the second flange lubricator at the east portal of Tunnel 26. Were the traction surfaces of the rails found to be fouled with grease at either lubricator location? Are there better places to locate these devices?


end


27 August 2026

1757 - Lake Ontario, "Sir ..."


from: Pictorial History of the Thousand Islands; Ed: Adrian G Ten Cate; 1982; Besancourt Publishers.

Your quarrel is not with The Honourable Douglas Robert Ford Jr. nor the Liquor Control Board of Ontario.

Yours sincerely,


 (Pierre Boucher de Labroquerie)


PS: My best to Jamieson, his French is passable. His time at Sorbonne Université was not ill-spent.

Now that he has a few days off, might I suggest a few 'discoverable' episodes of La petite vie ?


*  *  *


22 August 2026

Pre-Trip Steam Locomotive Inspection, Taking Slack, Cylinder Cocks, Sanding

'Lost' steam age rituals and technologies were mentioned in my posts about the Southern Pacific 1941 Santa Susana Tunnel accident. I thought it would be appropriate to provide some 'textbook' elaboration on the best practices for their use during those years.

These sections come from widely-used self-study texts for railway workers who wanted to improve their knowledge or to qualify for advancement. This book came from Rolly and may have been purchased by the engineer who previously owned Rolly's house. The text below was written by the CNR employee shown, and was copyrighted in 1928 and again (with updates) in 1937.

The 'value-added' reason for buying these textbooks ... was that they were thorough

If you were a roundhouse labourer who wanted to qualify to become a fireman, you could perhaps impress your fellow workers or bosses with what you knew and your demonstrated motivation to learn more. 

Or, if you worked for a smaller regional railway (not having the CNR or CPR's comprehensively-trained and supervised roundhouse staff) you could benefit from the knowledge and experience of someone who had worked for a large railway.

Today, these thorough textbooks help us understand all the forgotten details of the old technologies.

... However, we should bear in mind that what was done in practice on a daily basis might have been quite different.



East Oakland, 1955.
from: The Central Pacific and Southern Pacific Railroads; Lucius Beebe; 1963; Howell-North.


The Sunset Limited being greased en route, Lordsburg, New Mexico, undated.
from: The Central Pacific and Southern Pacific Railroads; Lucius Beebe; 1963; Howell-North.




'The Height of the Water in the Boiler'

CNR S-4-b Class, circa 1936. 
from: Constructed in Kingston; McQueen and Thomson; 2000; CRHA Kingston Division.

The 'water column' (older device = 'sight glass' or 'water glass', generically: a water gauge) is that tree of valves in the top right corner. Below the water column is the firebox (door) opening. The bottom of the coal-burning firebox assembly slopes down and away. 

The boiler backhead (the right 'end' of the boiler) will be contained in the cab. The water column is a sturdy device which serves as the window into the water level in the boiler. 

The fireman and engineer must keep the top of the firebox (the 'crown sheet') covered with water at all times. The water column registers the upper and lower limits of the flexibility they have with water levels in the boiler. The valves ('gauge cocks' in the text) are used to ensure that the water column is reading accurately. 

In a coal-fired firebox, the fire needs to be at least 1800 degrees Fahrenheit (~980 deg C) to completely burn the gases produced from the coal (a bright red fire). In a locomotive firebox, the fire can reach 2000-2500 degrees F (~1370 deg C) (creating a bright orange to a white fire). 

If the engine crew fails to keep the crown sheet covered with water, the fire will weaken the metal until it fails. The boiler will then explode: as the steam vents to atmosphere ... and as most or all the liquid water in the pressure vessel flashes instantly into steam. This is why several paragraphs are devoted to the subject of the water gauge.


Engineer posing while 'oiling around' with a flashlight in his left hand, no location given, 1957.
from: Canadian Pacific to the East; Omer Lavallee; 2007; Bytown.



*  *  *

Coupler and draft gear, freight car.
from: Car Inspection Manual; CM Drennan; 1940; Brotherhood Railway Carmen America.

In addition to the necessary free-play between two coupler knuckles when they are closed, 
systems are in place to cushion the lading and the car structure from normal slack action.



Engineer checking his train and traction while leaving a siding. Train 920, Santa Margarita, California, undated. 
from: The Last of Steam; Joe G Collins; 1960; Howell-North.


*  *  *


*  *  *

Sanding wet rail on a 1.75% grade.
Helmstetter's Curve, Cumberland, Maryland, undated.
from: The Last of Steam; Joe G Collins; 1960; Howell-North.




Working to correct a stuck sander valve, undated, no location. On the Great Northern.
from: Lines West; Charles L Wood; 1967; Superior.




Working as a fireman on a steam-powered eastbound freight climbing the ruling grade at Neys ... years later ... Rolly told me about working on an engine without any sand remaining in its sand dome.

A practice not covered in the textbook: He ran along the ballast beside his slow-moving train, looking for any grit he could find ... to throw under the wheels so they would not slip. 

If the driving wheels had slipped, the train would have 'stalled' ... i.e. It would cease to make forward progress with no hope of getting it underway from being stopped, while it sat on the hill.

... The only course of action left at that point would be to 'double the hill' ... move the train in two manageable pieces to the siding at the top of the hill. This would require the setting of hand brakes on the remaining piece of the train and would have blocked the main line for an hour or more.

I was given the impression that scrounging for grit (in season) happened more than once on this section of track.


15 August 2026

SP 1941 Tunnel 26 Accident - The Official Interstate Commerce Commission Report

Concise and to the point, the facts included in the official accident investigation were recorded in just over 6 typed pages. A diagram, executive summary and cover sheet bring the total up to 10 pages. 

The website to find US railroad accident investigations 1911-1993 is linked at the bottom of this page. 

Here is the sheet with the vital data and the summary of what was determined.


Below is an engine of the same class as Engine 4193, leading a passenger train. 

SP Cab-in-Front 4194, Train 55 The Tehachapi, undated, location unknown.
from: The Central Pacific & Southern Pacific Railroads; Lucius Beebe; 1963; Howell-North.

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The line diagram to the right represents an overhead view of the track plan. The headend of the train ran roughly to the midpoint of the 7366-foot Tunnel 26. There, an application of the brakes in emergency (after a knuckle break) gave the engineer, fireman, student fireman and headend brakemen few options.

Key points on the track diagram are linked to a track profile - the line diagram at the left. The engine stopped at the summit of Tunnel 26's 1% grade, just before the track transitioned to the slight descending grade leading to the west portal of Tunnel 26. (This is a very efficient method of presenting a lot of data.)

The box at the left shows the distances between the points listed.


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Images from Today

Google Earth, date: 30 August 2024.

Above: The two distinctive 90-degree curves at the east end of the image are found on either side of very short Tunnel 28. The railroad was engineered to decrease the gradient by adding distance. After passing through a rock cut, the line begins to turn west as it passes through Tunnel 27. The track curves to line up with the 7366 feet of tangent track through Tunnel 26. At the left edge of the image, the thin grey line of track exits at the west portal. It can be seen between the multi-lane highway and the winding Santa Susana Pass Road - which originally traversed these mountains.

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The grade to the east portal of Tunnel 26.

Below: In the lower right corner, the thin grey line of the railroad can be seen before it enters the rock cut (just below it is the smooth curve of an unnamed dirt road). The track passes through Tunnel 27. It then curves to the right to enter the eastern portal of Tunnel 26. It was on this track, and beyond inside Tunnel 26 that the Extra 4193 West got into serious trouble.

I don't know if the 1% grade is accurately portrayed in this image. The slow-moving train's flange resistance against the rails on the curves, combined with the gradient, challenged the motive power. On the night of the accident there were problems with driving wheel adhesion to the rail in this area and inside Tunnel 26.

East Portal of Tunnel 26 is at:  34°15'47.77"N 118°37'20.20"W
from: Google Earth, circa 2026.

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Signals, West Portal of Tunnel 26 at Hasson, undated.
from: The Central Pacific & Southern Pacific Railroads; Lucius Beebe; 1963; Howell-North.

Extra 4193 West never did reach these ABS signals at the east end of Hasson siding.

The single absolute semaphore controlled eastbound traffic at Hasson (entering the west portal of Tunnel 26).
The double semaphore controlled westbound traffic at Hasson (on the mainline or into the siding).

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This section provides a lot of civil engineering data, some of which I have illustrated with Google Earth images. 

There is no ventilation system for Tunnel 26. The wind through the tunnel in the report seems to correspond to the normal coastal wind patterns on land (i.e. The land is heated by the sun, warm air rises creating an area of low pressure, cooler air from the ocean is drawn into the area of low pressure. The cycle reverses at night). The normal wind currents between 24hr and 01hr - at the time of the accident - are not recorded. It seems logical that the presence of a train in the tunnel (with or without an engine) would obstruct most of the natural currents.

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Technical Exhibits

The post is one of a series about the railroad line, the motive power and the circumstances surrounding this accident. The terms in the report will be used to identify these devices - most of which have been described at length in previous posts. While the oil firing devices are generally of the type used by the Southern Pacific circa 1910, they won't necessarily match those in use on the engine 4193.


Conceptually: Emergency drop valve. The image shows the fuel valve closed (Fig 4) and with the valve open and the 'spring compressed' (Fig 5). This device is intended to stop the flow of oil and extinguish the fire in the firebox in an emergency ... or during the normal course of extinguishing the fire at a terminal.

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Oil-regulating firing valve. 
The (customizable) drifting stop-pin (c) is designed so that when the handle is placed with part (d) at that the stop-pin (c), it will be held in that position. This maintains a low fire and is analogous to 'idle speed' on an internal combustion engine. Moving the firing handle to the stop pin (f) cuts off the supply of oil to the firebox.

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The damper (e) admits air to the firebox. The damper control staff and the firing valve control staff descend through the cab floor ... with the oil regulating staff concentric with, and inside, the damper regulating staff. 

Generally, the damper should be opened more as the fire is increased (to meet the demand for more steam). A damper which is open more than necessary cools the fire and decreases steam production. A damper which is not opened enough leads to inefficient combustion and excessive smoke production which coats the flues with soot.

* If the engine is slipping, "the fireman must swing the oil regulator open, so as to give a good strong fire during slipping" (to avoid flue damage). 

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Photos from a '4100 class' Cab-in-Front
Note: This implies any class from AC-4 (1928) to AC-8 (1939).

It is not necessarily identical to the cab of the 4139 (AC-8 class). 

The History of Western Railroads; Jane Eliot; 1985; Bison.

The view looking from the left cab wall, over the fireman's seat, toward the engineer's side of the cab. 

The firing valve can be seen above the damper control. (The open-closed positions may be reversed from the diagrams above. i.e. Here, the firing valve may be closed.)

The Worthington gauge gives a readout on the boiler feed pump pressure.

In general, steam locomotives transmitted energy to operate pumps and other auxiliary appliances in the form of steam. Valves which sent steam down pipes were the common controls used by the engine crew. (Electricity on steam locomotives was an evolutionary 'add on' and electrical generation was generally performed by steam-driven turbo-generators.)


Control Labels, Left to Right
  • Blower: Sends live steam up the smokestack to artificially draft the fire. An essential device for preventing dangerous draft reversals which result in combustion gases being blown into the cab.
  • Oil (line) Heater: Heats the Heavy Bunker C Oil to 150-180 degrees Fahrenheit so it flows smoothly and atomizes correctly in the firebox.
  • Blow Back: Used to direct high-pressure steam to clear obstructions in the fuel line: back to the tender tank, or forward to the burner.
  • Atomizer: Supplies high pressure steam to the lip of the oil burner to shear the oil stream into a mist of fine droplets so it can burn. This is constantly adjusted at the same time as the oil regulator valve so the steam/oil always combine to produce an efficient fine mist. And, as mentioned above, the damper opening must also be adjusted to match the fire's needs.
  • Tank Heater: Sends steam through heating coils in the tender so the oil temperature is maintained at 100-120 degrees F to ensure it flows well.
  • Feedwater Heater: Uses waste steam from the cylinders and air pumps to raise the temperature of water being fed into the boiler to 200-230 degrees F. This improves thermal efficiency and prevents damage to the boiler from 'thermic shock'.
 
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I Like Trains; ed: David P Morgan; 1980; Kalmbach.

Looking across the cab to the engineer, the fireman would see this. However, only an engineer posing for a Ward Kimball 'last run' story for Trains magazine would accept having a spotlight shining in his face (for the benefit of the photograph). You can imagine how dark the cab would be inside Tunnel 26 without this kind of unusual interior lighting. 

In the fireman's view, you can see two armoured cables leading to shielded lights over the gauges and the firing controls. On the engineer's side, a similar fixture is arranged over his gauge cluster.

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The History of Western Railroads; Jane Eliot; 1985; Bison.

Presumably, in the same '4100-class' cab, we are looking at the engineer's forward-facing seat. We were just looking at the opposite side of the flat panel at the far right - which holds the fireman's gauges. Nowhere in these two cab views can I spot an obvious emergency cable control to shut the emergency drop valve to stop the flow of oil at the tender.

In the Discussion section of the report (farther below), the most junior person in the cab (the student fireman) will state that the engineer had difficulty closing the throttle throughout the trip. Many readers will know that when the driving wheels begin to slip, closing or decreasing the throttle quickly is necessary to stop the slip ... so the throttle can be opened slowly to re-gain traction before the train stops completely (i.e. the train 'stalls'). Dried sand can be blown down on the rail head in front of the driving wheels to help maintain or regain traction.

Comparing the two cab views immediately above, you can see that the 'spotlight in face' engineer has an ergonomically superior throttle - a upper quadrant type whose long arc of travel allows more precise adjustment.

In contrast, the throttle in the cab immediately above is mounted at some height above the firebox door. The engineer (as we imagine him in his empty seat) must reach above his head on his left-hand side to operate the throttle. You can see the handle is just above the engineer's gauge cluster. I believe the cutoff (reverser) lever handle is located immediately beside where the engineer's head/left shoulder would be.


  • There was adequate sand to support traction and prevent slipping.
  • The oil supply was left 'on' slightly.
  • The coupling failure was a new 'clean break' with no indication of earlier weakening. (Coupler knuckles are used like fuses ... they are engineered to break first - before serious damage is done to cars' draft gear.)
  • Theoretically, if the crew had foreseen being stuck in a tunnel, four respirators could have been signed out in Los Angeles (total on hand: six). If a photo I have seen is correct, this was a full head-covering hood with a hose exiting the top, and with a small window in the front. These hoods take air from the main air brake reservoir. The reservoir pressure is stepped down and the air is filtered, for emergency breathing.

SP Cab-in-Front 4233, south of Alturas, California, 1955.
 from: The Central Pacific & Southern Pacific Railroads; Lucius Beebe; 1963; Howell-North.

The photo of a 1942 AC-10 class is shown above to provide a reminder of the size and power of these locomotives. It also demonstrates the towering power of the engine's exhaust. The headend brakeman can be seen through the front windshield on the fireman's side.

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Before modern diesel-electric technology completely replaced steam locomotives, the few inches of slack between each set of car couplers was used as part of the most common tactic for starting a heavy train.  

... In 'taking slack' the engine reverses into the train, to eliminate the spaces between the couplers. Beginning to pull the train with the 'slack bunched', the engine theoretically starts just the first car in motion, then just the second car, and so on until the front of the train has gathered momentum so there is no danger of driving wheels slipping.

... The Extra 4193 West might have had 30-40 feet of total slack between all the couplers ... so, when starting after bunching slack on level track, the engine may have advanced 40 feet before the caboose started moving.

The crew on the engine were as follows (from newspaper reports):
  • Engineer, age 46 ('the person in charge' of those on the engine).
  • Headend Brakeman, age 52, technically 'train crew' under the conductor - not 'engine crew'.
  • Fireman, age 24, hired just two months earlier. Directly responsible to the engineer.
  • Student Fireman, age 24.
(The conductor age 61; the tailend brakeman, age 25; and the tailend brakeman who died - age unknown, are essentially out of the picture and near the tunnel's east portal. They are in or near the caboose. Technically, the conductor is in charge of the whole train. Hand/light signals will not work reliably along the side of the train in the tunnel.)

It is not clear why one would assign a (probably) probationary employee, on a full tonnage train, to train a student ... at night. It seems probable that the student fireman was present on that typical railroad procedure of that era: the 'unpaid trial trip' to learn the job and/or the railroad line. It is possible the student 'just showed up' - hoping for the usual unpaid training help from the working crew.

... A steam locomotive requires the fireman and engineer to know where a hot fire and extra steam will be needed - miles in advance. The fireman must know the characteristics of the road ahead and new firemen would start developing a 'firing plan' on the line where they worked to avoid the career-enduring nickname 'Coldwater'. Needless to say, the fireman must also know how all the unlabelled controls on his side of a steam locomotive cab are to be used.

To Preserve Life (with the benefit of hindsight)

There was only 2 feet of clearance between the side of the engine and the wall of the tunnel. The safety valve was venting the excess boiler pressure (scalding superheated steam) in a very confined area at 250 PSI. This pressure had been built up in order to pull the whole train up the 1% grade. The headend brakeman is excused for not wanting to uncouple the engine from the train at this moment. 

Probably, the 'slipping, then stalling in the tunnel, with the train brakes going into emergency' would have been a scene of incredible chaos, heat and noise in near total darkness. Communication would have been extremely difficult. The crew would have been aware that they were rapidly losing breathable air as the firebox pulled in oxygen and created oil smoke.

If we accept that it was impossible to uncouple the engine, the engineer or fireman could instead have extinguished the fire immediately, waited for the venting steam to subside, uncoupled the engine from the train, and the engine would still have had plenty of remaining boiler pressure to run itself out of Tunnel 26. 

... Then ... the unknown reason for the emergency brake application could have been determined and corrected. This would probably have blocked the main line for a couple of hours. The engineer might have faced discipline and demerit points for poor train handling ... or ... for accepting an engine with mechanical defects at the roundhouse. 

... However, the local railroad culture probably would not have much patience for an engineer who delayed trains because he was always throwing hissy fits about a sticky throttle or a leaky cylinder cock. (Childhood story books never accurately present the difficult realities of being an engineer.)

The mature headend brakeman might have been serene about the possibility of losing his job for 'abandoning' the train. He did save his own life and that of the student. 

Each of the two senior men on the train was associated with the death of a more junior employee under their immediate supervision. Engineer: fireman. Conductor: tailend brakeman sent to the headend.



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Possible cylinder cock leaking. 
from: The Central Pacific & Southern Pacific Railroads; Lucius Beebe; 1963; Howell-North.

Without realizing what I was doing, I may have provided an example of the kind of defect that the report describes at the 'Left, Number 1 Engine' cylinder cock. This detail comes from the previous train image above. The report perhaps suggests that the driving wheels of the 'Number 2 Engine' lost traction and slipped because of the film of water laid in its path by the leaking Number 1 Engine cylinder cock in the confines of the tunnel.

When I was trying to learn more details about this accident and did not realize that I could find and read the Official ICC Investigation, I found a message board conversation where someone wrote something like 'Yeah, I heard the slipping/the accident was caused by steam in the tunnel coming from a leaky petcock. In the tunnel the wall directed the steam/water onto the rail.' 

... I looked at the employee timetables and I have a different theory about the slipping which I hope to review and explain (as a possibility) in the next and final piece about this event. 



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Locomotive Record Cards for the 4193

Form 4395; California State Railroad Museum; archive.org.
https://archive.org/details/form-4395-4150-4304/page/n89/mode/1up

The damage from the accident seems to be recorded on the 'detail side' of the card, seen below. The date to look for is 17 December 1941.

On the card above, 'Vacated' is the Southern Pacific term for taking a steam locomotive off the roster: 27 September 1956. 

It is interesting from a corporate accounting perspective to see that the Ownership (above) was recorded as Southern Pacific Railroad, however, the SP subsidiary company El Paso and Southwestern Railroad became the engine's owner on 1 January 1955.


Cylinder cocks: Air, Stm (above)

Cylinder cocks exist to drain water from the cylinders ... through a small port in the cylinders' bottoms. Water is not compressible so an excess amount of condensed water in a cylinder can cause bent driving rods, or it can blow the cast iron head of the cylinder off.

The SP 4193 was originally fitted with manually-operated compressed-air-activated cylinder cocks. While starting (for example), the petcocks were opened when the engineer used his remote-control air valve and line to allow the cylinder pressure to blow the water out of the port at the bottoms of the cylinders. 

Rolly once told me: 'You only have to open them for a second!' ... to blow out the water - otherwise you're wasting steam. 

When you watch the North American restored corporate steam locomotive videos, you'll observe that they'll often open the petcocks for multiple cylinder cycles to create huge crowd-pleasing clouds of steam as the engine departs. Just like the black smoke created for Lucius Beebe and the photographers of that era, these petcock steam displays are wasteful theatrics.

The switch to steam-activated cylinder cocks eliminated the challenge of routing long, compressed air lines to the cylinders (especially on the Cab-in-Front engines). Compressed air lines become contaminated with condensation and on some of the territory operated by the SP, this condensation would freeze and block the line - risking the previously mentioned damage to the engine.

In addition to always using hot, live steam lines ... the steam cocks were also designed to operate automatically, removing any human error from the protection of equipment. 

... When the steam pressure in the special device's differential piston was overcome by excessive pressure in the cylinder, the pop valve opened automatically to expel the water.

From the cards, I could not determine which type of cylinder cocks the 4193 had at the time of the accident.


Form 4395; California State Railroad Museum; archive.org.
https://archive.org/details/form-4395-4150-4304/page/n89/mode/1up

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