Alternative Fuels in Los Angeles Transit: History & Resources

Page content by Danny Seplow

Pollution has been a problem that has challenged Los Angeles for over a century. Geographic features make smog prone to stay above the city and urban sprawl has created the demand for long-distance transit, most methods of which historically caused pollution.

Early efforts to reduce smog were primarily due to health concerns and trying to improve the appearance of the city. Inhaling smog was dangerous and residents thought it ruined the aesthetic of ‘Sunny California.’

More recently, planners have also been keen to reduce pollution due to the negative environmental impact it has and its contribution to climate change.

This article is not meant to be a complete definitive history of pollution in Southern California, but instead an investigation into some of the responses to pollution by LA Metro and its predecessor agencies, including the trial, adoption, and public relations campaigns of several alternative fuels.

The article aims to show the ways that bureaucracy, government, and technology respond to environmental concerns and why some alternative fuels never left the testing stage while others saw fleet-wide adoption.

Early Hybrid Fuel Pilot Projects

The earliest recorded tests for alternative fuel buses date back almost to the beginning of bus service in Los Angeles overall.

Pacific Electric Railways and Los Angeles Railway launched their joint venture for the first regularly scheduled bus service in Los Angeles on August 18, 1923, along Western Avenue. Service on Wilshire Boulevard began the following month and eight more routes soon followed.

By 1925, Los Angeles Railway was already experimenting with hybrid fuel prototypes, running “gasoline-electric” double-decker buses, made in California. (Coincidentally, they were colloquially known as “the green busses,” several decades before the term “green” was commonly used for environmentally-conscious endeavors).

These buses were deployed as auxiliary vehicles to streetcars. Their unique features included six-cylinder engines under the hood, but instead of being connected with a transmission, they were connected to a generator which developed electrical power for two motors — one on each of the rear wheels.

Another benefit to the new technology was smoother rides, in that gear shifting was not necessary for operation.

From November 29, 1925 Los Angeles Times article on new gasoline-electric powered bus testing.

We continue to research the history of this project and why it was not more broadly adopted. One clue may be that the Los Angeles Times noted on November 29, 1925 that:

None of the bus lines are making a profit, and the Sunset Boulevard green busses and the Los Angeles Railway busses on Melrose Avenue are the only ones on which the revenue comes within speaking distance of the operating costs…[and] the immediate financial outlook is not particularly rosy.

The Pollution Problem

Los Angeles has had a smog problem almost as long as it has been a city, dating back to at least the turn of the century. However, this early pollution was blamed on factories and other heavy industries. Measures were taken in the first two decades of the 20th century and smog was mitigated temporarily.

Starting in the 1940s, the rise of the personal automobile dramatically increased air pollution. Smog became so severe that it started acting as a type of weather of its own, even affecting aviation.

Nevertheless, citizens believed that factories were still the primary cause of pollution, especially with the increased industrial output during World War II.

It was not until 1945 that experts began writing articles attempting to educate the public about the real causes of smog.

They tried to show how it was not just factories, but numerous sources including locomotives and automobiles that produced smog.

Moreover, they highlighted that the geography of the Los Angeles Basin meant that smog remained trapped by the mountains and with few winds to blow it away.

It was around this time that smog got its name as a portmanteau of ‘smoke’ and ‘fog.’

Throughout the late 1940s and 1950s, government officials began taking great efforts to begin cleaning up the smog problem.

They first tackled industrial pollution from factories and garbage burning.

Automobiles proved to be more difficult to regulate, especially as Los Angeles had begun to sprawl and many residents had long commutes to work making them wary of any changes to their cars, especially ones that could damage their engines.

A joint proclamation issued by a group of Los Angeles civic offices, encouraging Los Angeles residents to carpool and to follow the given burning schedule in an effort to reduce smog levels, c. 1950s.


‘Clean Diesel’

In the new political environment that was looking for any sources to blame for pollution, bus companies went on the defensive, especially with regard to their new diesel buses they had recently adopted in the 1940s to replace their older gasoline buses.

Diesel was a more energy-dense fuel than traditional gasoline, giving them better fuel economy. The bus companies attempted to prove to the public that their fleets were clean and not a contributor of smog.

An example of this can be seen in the August, 1951 issue of Pacific Electric Magazine which claimed that automobiles create more smog than buses, diverting blame from their fleet.

Similarly, the April, 1954 issue of Metro Coach News claimed that an independent laboratory had run tests that found GMC engines to be free of both air pollutants that cause smog as well as carbon monoxide.

These efforts continued into the 1960s with the Los Angeles Metropolitan Transit Authority (LAMTA) claiming in their June, 1963 employee news magazine that diesel engines contribute less to air pollution than comparable gasoline engines and that contributions of diesel MTA buses were a tiny fraction of total pollution in LA

General Motors even put out a video in 1967 that described the benefits and cleanliness of diesel engines.
The Answer is Clear was a production of the Detroit Diesel Engine Division of General Motors Corporation, 1967. An infomercial, presented in part as a slice of life on a bus, the film stresses the benefits of diesel and is focused on persuading viewers that diesel-powered buses do not pollute the air. Shot in Los Angeles, it features Wally Cox, a well known 1950s television actor.


Early Alternative Fuels Studies

The Southern California Rapid Transit District (SCRTD) replaced LAMTA bus service in 1964.

By the 1970s, SCRTD had begun investigating possible alternative fuels, including compressed natural gas (CNG), liquified natural gas (LNG), and liquified petroleum gas (LPG or petroleum).

They conducted a study to investigate whether these gaseous fuels could be used for automobiles, light trucks, and minibuses

CNG was tested on several buses in the early 1970s but SCRTD found that low mileage meant the fuel range was insufficient to be able to operate on CNG alone.

LNG was found to similarly lack mileage, negatively affecting its range, as well as being prone to explosions if proper precautions were not taken.

LPG was used by several of SCRTD’s predecessors in the decades prior, but also had the possibility of catching fire if proper mitigation measures were not taken.

However, for both LNG and LPG, the risks of explosions were almost zero.

While the alternative fuel study was optimistic that diesel engines would continue to decrease emissions in the future, it did find that gaseous fuels had lower emissions.

However, SCRTD had budgetary and availability constraints that made them impractical for wide-scale adoption at the time.

The study recommended that SCRTD stick with diesel for its automobiles and light trucks, but that minibuses operating downtown adopt LPG because the pedestrian-heavy area meant clean emissions were more valuable than fuel mileage.

While this study made no investigation into full-sized buses or rapid transit, it demonstrated the SCRTD’s focus on alternative fuels rather than trying to convince the public that diesel was clean energy.

SCRTD, and other transit agencies, would continue looking for alternative fuels. 

The California Steam Bus Project

In the early 1970s, several local and federal transit agencies experimented with external combustion engines (ECE) in a steam-powered buses.

The advantages of the ECE over traditional diesel engines are that they would produce fewer emissions, run quieter, and do not need to have gear shifts.

This was not the first time that steam engines had been used in the automotive industry.

They had briefly been used in cars in the early 1900s, but they lost popularity due to difficulty starting the engine and fears that they might explode.

Both of these problems had been solved by the 1970s and steam-powered buses were ready for a major test.

Dubbed “The California Steam Bus Project,” the California State Assembly greenlit a trial run of the conversion of three diesel buses into three different steam buses configurations using funds from the federal government.

The California Steam Bus Project, the first federally-funded alternative fuel transit bus project, debuts in Los Angeles, San Diego and Sacramento in August, 1972. The buses ran on steam engines, a propulsion system designed with William Lear, of Lear Jet fame. After the test, engines were removed and later used in a steam-powered Lear race car that set a world land speed record.
Prototype SCRTD steam bus
SCRTD 6200 steam bus power plant

Legislators and bureaucrats alike, at all levels of government, saw steam-powered buses as the clear solution to recent environmental regulations and the future of public transportation.

The guiding principle was that, while also powered by diesel, a steam engine can more thoroughly burn the fuel, leading to fewer emissions.

SCRTD joined transit agencies in San Francisco, Sacramento and San Diego in testing the feasibility of using external combustion engines, the most familiar of which is the steam engine — technically known as the Rankine cycle engine.

Steam-propelled road vehicles dated back to a French tractor in the 1760s, and steam buses debuted in London in 1919 and in Detroit and New York City in the 1920s.

Here at home, the California Legislature had been addressing motor vehicle air pollution since at least 1959.

It determined in 1967-68 that state and federal agencies’ findings regarding alternatives to the traditional internal combustion engine warranted further investigation regarding application to transit.

The State Assembly decided to sponsor a demonstration project which evaluated the technical feasibility and public acceptance of external-combustion engines as low-emission alternatives to contemporary city buses.

The project was funded by UMTA, the Urban Mass Transit Association (the predecessor to the Federal Transit Association), and was the first federally-funded demonstration project related to alternative-fuel transit buses.

Los Angeles Mayor Tom Bradley
Los Angeles Mayor Tom Bradley inspects the engine bay of a steam-powered bus, August 20, 1972.

In 1970, three different contractors began engineering systems for three different transit agencies in California.

William M. Brobeck & Associates of Berkeley was paired with nearby Alameda-Contra Costa Transit District (AC Transit) headquarted in Oakland, Lear Motors Corporation of Reno, NV was matched with San Francisco Municipal Railway (SF Muni), and Steam Power Systems of San Diego partnered with the Southern California Rapid Transit District in Los Angeles.

The California Assembly Office of Research provided overall direction to the three-agency project, assisted by two systems management firms.

They participated in two high profile demonstrations.

The Brobeck-AC Transit team effort was shown off to U.S. Department of Transportation officials, members of the U.S. Congress and guests in Washington D.C.

The U.S. Department of Transportation (USDOT) even held a symposium in 1971. Representatives of the DOT, the U.S. Environmental Protection Agency, local leaders, and bus companies all attended and gave presentations about the advantages of the steam bus.

On April 26, 1972, all three steam buses were demonstrated before members of the California Legislature in Sacramento.

At the Steam Bus Symposium, William P. Lear, Chairman of the Board of Lear Motors Corporation, stated:

The present ICE [internal combustion engine] and diesel power plants have cost many billions and taken half a century to develop. In much less time, and for a great deal less money, steam can equal and exceed their performance and economy while eliminating pollution outputs. We consider our present results as encouraging but far from the ultimate in steam vehicle power plants for both cars and buses. The future is most promising; but, like all good things, will require more time and a lot more money than can be provided by one individual or a small corporation.

The California Steam Bus project initially seemed to be a success. It performed well in clean running, fuel economy, revenue service, and noise reduction.

The few categories where it did not outperform older diesel buses were attributed to the buses being adapted diesel buses, not even pre-production models.

The assumption was that they would improve with further revisions and refinements. Moreover, the steam bus was supported by the public who were growing increasingly concerned about the levels of smog and pollution.

The 1972 film Steambus explores the history of steam power and looks at the steam engine as a possible alternative to reduce traffic-induced air pollution.

It examines the California State Legislature’s federally-funded steam bus project, initiated in 1968, to develop a steam-powered bus.

Metro Transportation Research Library & Archive has preserved the only known copy of this film in existence, which can be viewed in two parts here:
Part I of “Steambus,” by Peter Adair and Pat Jackson, for KQED, 1972.
Part II of “Steambus,” by Peter Adair and Pat Jackson, for KQED, 1972.

Overall, the Steam Bus Project resulted in numerous findings regarding the use of Rankine cycle engines for public transit buses.

Acceleration, top speed and hill climbing were equal to or exceeded road performance of buses powered by six-cylinder diesel engines.

Tests conducted by the California Air Resources Board showed steam buses to be well below the 1975 California emission standards for heavy duty vehicles.

The California Highway Patrol reported that the quietest steam bus was 2.5 to 10 decibels below the quietest diesel buses in drive-by tests and 6 to 14 decibels below in curb-side tests, while interior sound levels were similar to or higher than diesels.

Conventional driver controls were used on the steam buses, minimizing special driver training.

And while these experimental vehicles also matched up well against diesel buses in the areas of revenue service (e.g. comfort, rider acceptance), they showed promise in their potential for further fuel consumption improvement and potential for emissions improvement.

In light of these glowing reviews regarding steam buses overall, what happened after the demonstration period was over?

Unfortunately, Los Angeles encountered more than its fair share of problems with the Steam Bus Project.

The California Steam Bus Project Final Report reports the Southern California Rapid Transit District experience as follows:

During the first week of public service, the SCRTD steam bus encountered numerous difficulties.

Its first two days of attempted public service on September 5 and 6 were aborted, because a bolt sheared on the combustor air fan assembly and a gear mechanism in the oil pump failed.

On September 7, the bus entered public service, but it completed only a one-way trip of 7.3 miles because a pulley slipped which prevented the fan from turning inside the boiler.

On September 8, the bus was withdrawn from public service when a boiler leak was detected; however, the bus traveled 86 miles on September 11 during performance testing until the boiler leak deteriorated.

After the bus was towed to San Diego and the repaired boiler was installed, the bus returned to Los Angeles on September 28 and re-entered public service on September 29, operating on Wilshire Boulevard.

It completed a successful 15-mile round trip with air conditioning operational and favorable performance, except for a loose battery terminal which caused a 27-minute delay.

The bus thereby completed its second and last day of public service because vendor and fleet operator contracts expired on September 30.

In 5.5 months since March, this bus logged 1,007 miles.

Ultimately, the Los Angeles Steam Bus from its San Diego-based manufacturer was in service for only two days, whereas the other test cities witnessed greater success.

Still, the California State Legislature’s Assembly Office of Research concluded that the Steam Bus Project successfully completed its goals.

Extensive surveys and measurements of community attitudes were conducted.

The steam propulsion systems were the first alternate power systems to be visibly supported by the public sector.

The participation of both public and private entities at an early date was viewed as very beneficial.

The Office went on to make several specific recommendations regarding the adoption of Rankine cycle engines.

It urged the exploration of an application for heavy duty vehicles in a research and development program including design engineering and bench testing rather than studies and demonstrations, including funding of at least $20 million over a four-year period.

Nevertheless, the steam bus failed to replace diesel buses. How did this happen if it performed so well during the tests?

The answer is illustrative of wider trends in the history of energy regimes and infrastructural changes. Put simply, there were too many hurdles and the advantages were not attractive enough to overcome them.

Large infrastructural systems, such as massive bus fleets, have inertia that make it difficult for them to change. Driving and maintenance differed slightly from diesel buses, meaning employee retraining would be necessary.

Moreover, once engineering problems were overcome, the steam bus was projected to cost slightly more than diesel buses as well as have worse fuel economy, making them more expensive to operate. 

To transit managers, these costs outweighed the benefits.

One aspect of the California Steam Bus Project was a survey sent out to transit managers across the country, both public and private bus fleets.

The results showed that almost all believed pollution to be a major problem but they also thought that buses were one of the smallest contributors to pollution, behind private automobiles, oil refineries, and factories.

As such, very few transit managers said they would be willing to pay a premium for a steam bus over a diesel one.

Survey question: “How much of a premium would your transit district be willing to pay [for a steam bus]?”

In addition, the steam bus was still years away before engineering would be perfected and they could start service. California needed more urgent solutions.

While not as clean as a steam bus, catalytic converters started becoming widespread in the mid-1970s to meet new environmental regulations.

These required no infrastructural changes and were not as costly as changing whole bus fleets to a new type of engine.

In the end, the steam bus failed not due to any fault of its own but because of the needs of transit managers and their perspective on pollution.

Enthusiasm for the steam bus was most likely influenced by global uncertainty about petroleum prices and the later OPEC embargo.

However, it was also emblematic of how those who make policy recommendations and those who directly run infrastructures have different priorities.

While planners look toward the future and see numerous benefits on paper, managers are more concerned with reliability and day-to-day operations.

This explains in part why the reports about the steam bus were so rosy but full fleets of them never came to fruition.

Moreover, investigators were optimistic that if the engine could be perfected for a steam bus, it could be employed in private automobiles as well, reducing emissions even further.

The California Steam Bus Project Final Report contains many more details about this pivotal moment in California’s alternative-fuel transit vehicle history, as do other reports in our online full-text access document collection.

The entire project was further reviewed in detail in a paper presented at the International Automotive Engineering Congress held in Detroit in 1973.

Response to OPEC Embargo

The DOT again launched an investigation into possible alternative fuels for buses in 1984.

Responding directly to the OPEC oil embargo of the previous decade, this study was not meant to replace diesel, only to offer possible alternative fuels to supplement diesel if prices were high or supplies were low during a national emergency.

They studied alcohols, vegetable oils, methane (natural gas), and hydrogen. In addition to investigating the efficacy of the different fuels, the report also analyzed if the current production of each fuel had the capacity to support bus fleets if need be.

The study found that only alcohol was a possibility for near-term implementation. The others would require redesigns of engines and fuel storage systems.

Moreover, it found that while all alternatives, except hydrogen (which required storage systems that would not be widespread for several decades), were possible alternatives, they should only be used if very necessary due to either high costs, limited supplies, or high pollution: 

In summary, vegetable oils are the only fuel with immediate development potential; ethanol has near-term potential, while methanol has near-term potential of the end user point of view (i.e., transit systems) but only long-term potential from the production point of view; methane is a long-term potential fuel, while hydrogen is a post-20th century potential bus fuel.”

Compressed Natural Gas (CNG)

In the 1990s and early 2000s, LA Metro became increasingly concerned about the harmful role that pollution played in climate change. No longer was mitigating pollution an attempt to curb smog, but it was now a critical goal to save the planet.

In 1993, Metro directors decided to only order clean vehicles in the future. After alcohol-based fuels, methanol and ethanol were too corrosive to engines, they opted for compressed natural gas (CNG). While marginally more expensive per bus, ~10-15% more, they reduced emissions by 80%.

This raises the question: why did the CNG bus succeed when the steam bus failed?

It was clearly not due to cost. In addition to being slightly more expensive, CNG buses also required the construction of brand-new custom refueling stations.

Instead, the answer has to do with how governments, bureaucracies, and technologies interact.

Part of the reason is that CNG is all domestically produced in America. Diesel, as seen during the OPEC embargo, was dependent on foreign markets and fluctuated with international politics.

The steam bus, despite its innovations and reduced emissions, was still powered by diesel. Furthermore, its low fuel economy meant it required even more gas than traditional diesel engines.

Another difference between the steam bus and the CNG bus is the timing of when they were proposed. In the 1970s, new solutions were still being proposed and weighed against each other.

It was only a few years after the California Steam Bus Project that catalytic converters became widespread. 

Another factor is that LA Metro was trying to set itself apart from the SCRTD.

It had only formed earlier that year in 1993 from a merger of SCRTD and Los Angeles County Transportation Commission (LACTC).

Taking a drastic step, such as committing to a fully CNG bus fleet, would help it differentiate itself from its predecessor and show the public that it was a leader in innovation.

However, it is impossible to narrow down only one or a handful of reasons why CNG succeeded and the steam bus. The economy, environment, politics, and science all interact with each other in complex unseen ways.

Electric Buses

More recently, LA Metro has begun using electric buses. In 2017 the board of LA Metro adopted a motion to move to a 100% zero-emissions fleet by 2030.

They were now driven more by concerns for climate change than public health. The first electric bus entered service in July 2020.

By October 2021, the Metro G (Orange) Line was the first line to completely transition to all-electric vehicles.

Over the next decade, Metro will continue to replace its approximately 2,300 CNG buses, reducing its carbon footprint and becoming carbon neutral.

First Electric Bus, Metro Orange Line Busway, Metro G Line. More information here.
Debut of the the Metro G Line/Metro Orange Line electric bus, July 27, 2020.


The history of alternative fuel adoption in transit characterizes the complicated relationship between technology and government.

It is not always the ‘best’ technology that is adopted, assuming that a ‘best’ technology can even be agreed upon.

A tradeoff exists between emissions, costs, upkeep, and many other variables.

Furthermore, politics and timing play a critical role in which technologies are widely adopted and which ones are not.

Transit agencies do not exist in a vacuum and must respond to factors outside their control.

Nevertheless, LA Metro has continuously strived to reduce emissions and meet the ever-evolving needs of the public, as demonstrated by the ongoing transition to electric buses.