Modern adaptive traffic signals rely on sensors like inductive loop detectors (ILDs) embedded in pavement and cameras mounted above roadways to detect the presence of vehicles and adjust signal timing accordingly. These systems aim to reduce congestion and improve safety. However, bad weather –like rain and fog—can cause sensors to fail or generate false signals, creating unnecessary delays and safety hazards. In addition, an emerging concern is “spoofing”, where individuals intentionally disrupt ILDs by sending false electrical signals. This could cause traffic signals to mismanage flow, increasing congestion and risk of crashes. Sensor fusion, the practice of combining ILD and camera data, is gaining traction as a solution for improving performance. To better understand the vulnerabilities and potential advantages, we tested how sensor fusion performed under a simulated range of traffic and weather conditions and how spoofing attacks affected signal control and object tracking performance.
California’s climate policies are accelerating the transition to zero-emission vehicles, but the construction sector faces a major barrier: access to reliable power at job sites. While electric excavators and loaders are entering the market, many construction sites—often temporary and in remote or constrained locations—lack the electrical infrastructure needed to support them. Grid connections are often too costly and take too long to install for construction projects, and existing grid infrastructure was not designed to handle the power demand of heavy machinery. Without practical charging solutions, electrifying the construction sector may lag behind state goals. Meanwhile, construction equipment is contributing 1% to 2% of California’s total greenhouse gas emissions.To better understand these challenges, we reviewed existing research, assessed available charging technologies, and spoke with utilities and energy providers across California. We focused on identifying key barriers and practical pathways to support construction electrification.
The COVID-19 pandemic catalyzed a massive and abrupt shift in work arrangements across the United States, with telecommuting (or working from home) becoming a dominant mode for a substantial portion of the workforce. This shift not only disrupted traditional employment structures but also significantly altered daily activity schedules and travel behavior. As policymakers and planners seek strategies to manage travel demand, mitigate congestion, and reduce greenhouse gas emissions, understanding the long-term implications of telecommuting on travel patterns is essential. The pandemic offers a unique opportunity to study these changes at scale and across diverse geographic and demographic groups.
In Walkable City, Jeff Speck says that induced demand is the thing that everyone in city planning understands but doesn’t talk about. It may be more accurate to categorize induced demand as the thing that everyone in city planning talks about but doesn’t understand. The issue is muddied by inconsistent definitions of relevant terminology.
Fare-free transit programs are increasingly used to increase ridership and reduce household transportation costs, especially for lower-income households. In California, where fewer than ten percent of school trips are made on school buses and many students travel long distances to reach school, transit costs and access can pose real barriers to education and after-school opportunities. At the same time, fare-free programs require substantial and ongoing public investment, raising important questions about whether eliminating fares alone is enough to meaningfully change student travel behavior.
The COVID-19 pandemic fundamentally changed how Californians travel, work, and shop. While overall travel levels have largely recovered, the rise of remote work, online shopping, and more flexible schedules have reshaped when, why, and how people travel. Yet many transportation policies and planning tools still rely on outdated assumptions about travel behavior, creating a growing mismatch between policy and reality, with implications for infrastructure planning, congestion, air pollutant emissions, and more. To better understand these changes, we analyzed travel data from 2019 and 2023 across four primary travel modes–driving, public transit, walking, and bicycling. To examine changes in driving and transit, we used data from sites around the state for driving and transit use, in additionto data from the Southern California Association of Governments (SCAG) region to analyze walking and biking.
In California and many other states, new development projects must undergo an environmental impact analysis as part of the approval process. In California, this happens through the California Environmental Quality Act (CEQA).
While CEQA is designed to ensure thoughtful consideration of environmental effects, it can also invite litigation that can delay or derail projects, even for projects that may benefit the environment, such as transit-oriented development (TOD). TOD aims to reduce vehicle miles traveled (VMT) and its associated impacts, such as greenhouse gas emissions (GHGs), by locating housing, jobs, and amenities near high-frequency public transit. But when environmental review requirements delay or discourage TOD, the result can be to push development to less accessible areas, leading to more driving, more emissions, and fewer housing options—
undermining the very goals CEQA was meant to protect.
California’s climate goals increasingly depend on shifting electric vehicle (EV) charging to midday, when clean, low-cost solar energy is most abundant. Doing so could help utilities avoid having to curtail solar energy and prevent reliability-driven infrastructure upgrades that would raise rates for all customers. Workplace charging programs are well positioned to support this shift, as many vehicles remain parked during daylight hours. However, workplace charging presents a cost dilemma. Since home charging is typically less expensive, employees may be reluctant to use workplace chargers unless prices are heavily discounted—yet offering free or low-cost charging extends the time it takes for employers to recoup infrastructure investments.
Building a large, reliable, equitable network in a short time presents challenges of scale, reliability, and resiliency. One possible way to address these challenges is to combine light-and heavy-duty vehicle charging and fueling infrastructure, given the overlap of these vehicles’ travel patterns and of the respective charging and fueling technologies used. We investigated how this strategy could support robust charging and refueling networks for projected ZEV growth. To that end, we developed a “conservative” and an “optimistic” scenario to simulate charging and hydrogen fueling station deployment across California for 2025, 2035, and 2045.
In October 2021, the Los Angeles Count Metropolitan Transportation Authority (LA Metro), in collaboration with other regional transit operators and multiple school districts across the county, launched the GoPass pilot program to offer free transit passes to K-14 students, which became permanent in early 2024. Students in a high school district in the Greater Los Angeles area were surveyed to determine the reasons students decided to participate in GoPass and how the students subjectively valued their travel preference. Students were less likely to participate in the GoPass program if they had the use of a car for trips to school but more likely if they had the option to take transit for trips leaving school. Student demographics did not play a large role in whether they participated in GoPass. Students highly value cars and trip amenities, such as onboard Wi-Fi. They subjectively value reduced travel time at $71/hour, similar to other studies among adults, but valued reduced waiting time at $98/hour, again consistent with other studies that find a high relative value for shorter waiting time. Students are not likely to be persuaded to take transit merely by making it free. Instead, school districts may consider increasing the cost for campus parking permits and reducing the number of campus parking spaces to encourage greater use of transit and shared travel modes.
