Ridership data and work trends continue to undermine the case for a second BART tunnel 
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Ridership data and work trends continue to undermine the case for a second BART tunnel 

Remote work has become the norm rather than the exception for many types of employees, especially in the Bay Area.

Before the COVID-19 pandemic and the boom in remote work, the San Francisco region’s Bay Area Rapid Transit (BART) was orried about capacity constraints and started planning for a second rail tunnel between Oakland and San Francisco. But, an analysis of ridership data published by BART suggests that the new tunnel, estimated to cost $29 billion, is no longer needed, in part due to the expected long-term changes to travel patterns induced by COVID-19. 

To its credit, BART publishes hourly station entrances and exits by station pair on its website. For each hour, the data set shows how many individuals traveled between any two named stations throughout the system. By classifying stations by the side of San Francisco Bay in which they are located, it is possible to estimate the number of hourly trips passengers took beneath the bay. 

If cross-bay ridership in any given hour approaches the system’s capacity, there is a case for adding capacity by, for example, adding a second tunnel. But, if usage is well below capacity, large capital expenditures to increase capacity are not warranted. 

While ridership varies widely across days and times, it is best to focus on the busiest travel times, which have historically been the morning and evening rush hours. Suppose the existing tunnel is reaching maximum capacity. In that case, a new tunnel may be needed irrespective of usage during less busy periods (although authorities might also consider negotiating arrangements with large employers to stagger employee hours, implement variable fares to deter peak travel, or use other techniques to lower utilization during peak periods). 

Today, the theoretical capacity of the single BART San Francisco Bay tunnel is 48,000 passengers per direction per hour based on a maximum of 24 trains per hour, 10 cars per train, and 200 passengers per car (representing what BART officials call “crush capacity” with standees packed into each car like sardines). For various reasons, not the least of which is passenger comfort, planners should try to avoid approaching this theoretical maximum.  

BART is already investing in a capacity increase. By upgrading its train control system and purchasing more rolling stock, the system should be able to run 28 cars in each direction under the Bay by 2030, raising the theoretical maximum to 56,000. This upgrade project, known as the Transbay Corridor Core Capacity Program, has an estimated cost of $2.7 billion, including $1.2 billion in federal funding. 

I examined BART ridership data for the last eight years to determine whether a second tunnel is needed. For each month between January 2015 and July 2022, I found the highest single hour of cross-bay ridership, as shown in the accompanying chart. Between 2015 and the pandemic’s beginning, peak hour usage hovered around 30,000—comfortably below today’s theoretical maximum.

However, the data shows a slight upward trend, even though BART’s total ridership declined during this period. Further, the all-time peak of 33,794 was reached recently in May 2019. This evidence supports the need for the Core Capacity Program, and possibly, during the pre-pandemic period, may have made the case for the second tunnel.

However, as one would expect as the COVID-19 pandemic really hit the United States in March 2020, BART's peak hour ridership declined sharply in March and April 2020.

Over the past two years, ridership has been recovering slowly. There was a significant bump in June 2022, but that was the result of East Bay residents traveling to San Francisco to join in on the Golden State Warriors NBA championship parade and not indicative of any regional commuting trend. 

In July 2022, BART's peak hourly cross-bay ridership was just 27% of the level reached in July 2019. This percentage is considerably below the 34% to 35% levels BART reported for all-day ridership on most Tuesdays, Wednesdays, and Thursdays in July.

BART computes its ratios by comparing overall daily ridership in July 2022 to pre-pandemic levels. The difference between the ratio I calculated and those reported by BART is consistent with the intuition that, in the current pandemic era, work and travel patterns are more varied, with the share of riders using mass transit for their traditional morning and evening commutes falling as a percentage of total trips. 

To determine whether building a second transbay tunnel is a wise investment of public funds in the coming decade, one must answer two questions: Will overall system usage return to and then exceed BART's pre-pandemic levels? And will BART's ridership once again become more concentrated at rush hour peaks?

Mounting evidence suggests that the answer, at least to the first question, is no. 

In the early months of COVID-19, most urban planners worked on the assumption that there would be a discrete end to the pandemic, after which offices would reopen, workers would return, and BART would rapidly recapture most of its lost ridership.

That discrete ending may have appeared to be in sight during the COVID-19 vaccine rollout early in 2021. But, instead, the pandemic has been prolonged as new COVID-19 variants emerged, Bay Area case levels experienced multiple spikes, and many workers have resisted returning to offices.

Now, it looks like there will not be a clear or sudden end to the pandemic, but rather a gradual transition to endemicity, with COVID-19 remaining a background threat to many, including those with underlying health risks and conditions, for the foreseeable future. 

Given the combination of COVID and new technologies, remote work has become the norm rather than the exception for many types of employees, especially in the Bay Area. According to a survey of mid-size and large public firms conducted by the San Francisco Standard, "More than half of the 73 mid-size and large public firms with headquarters in San Francisco said their office workers can work remotely full-time for the foreseeable future, according to publicly available company information, employee interviews and job postings." Most other companies intend to use a hybrid model where employees work on-site fewer than five days per week. 

Another factor limiting commuting is the slowdown in technology industry employment growth. We may be reaching the end of the megatrend toward increased use of online technologies leading into the pandemic and then accelerated by it as people avoided in-person contact. Now that most people have become willing to return to physical stores and restaurants, technology utilization is flattening along with the demand for software engineers.

The Mercury News recently reported, "In an unsettling trend, some tech companies such as Apple, Google, Facebook app owner Meta Platforms and Tesla have revealed plans to pause or scale back hiring amid ongoing economic uncertainties."

"The rebound from the pandemic appears to be losing steam, and hiring is clearly slowing in the tech sector,” Mark Vitner, senior economist with Wells Fargo Bank, told the Mercury News.

It is possible that local technology hiring could rebound in the coming years, and it is also possible that San Francisco’s economy could experience a rotation in which another growing industry sparks a new round of employment growth. But current evidence suggests that the number of individuals commuting to work in downtown San Francisco may not return to 2019 levels for decades, if ever. 

As to the second factor that determines needed BART capacity under the Bay—whether commute times will once again become concentrated during the typical rush hours of 8-10 am and 4-6 pm— less evidence is available. However, we know from surveys conducted by Adobe Corporation and others that many employers have adopted flexible work schedules since the onset of the pandemic and that employees would like to see them go further in this direction.

So, the traditional 9-to-5 workday and its concentrated commuting pattern may become a thing of the past. Other research suggests that inbound commuting times are becoming more variable post-pandemic than outbound commutes, but, in the case of BART, inbound passenger volumes were more concentrated than outbound volumes, so this trend will most likely lead to the two commute peaks balancing out at much lower levels. 

While we should not completely rule out the need for a second Bay tunnel someday, the $29 billion required to build it could undoubtedly be reprogrammed to support other infrastructure projects that have a far greater chance of benefiting the Bay Area in the near-to-intermediate future.