I analyze drone video footage of bottlenecking at East Bayshore Rd & Laura Ln in Palo Alto, which negatively impacts East Palo Alto residents driving home during PM rush hour.

Problem

Over the past 2 years, I have experienced heavy traffic during PM rush hour (4pm - 6pm, particularly Tues - Thurs) on East Bayshore Rd when driving home. I had observed cars backing up on the Palo Alto side of East Bayshore Rd from Laura Ln to Embarcadero, and then cars backing up further along East Bayshore Rd from Embarcadero to the end of the office buildings (Fig 1). For a 40 minute drive home from Mountain View, around 20 minutes was spent getting from Embarcadero & East Bayshore to home. And around 10+ minutes of that time was spent in traffic on East Bayshore Rd.

Impact on East Palo Alto Residents

The impact is that it takes longer for East Palo Alto residents to get home and for cut through traffic to reach the Dumbarton Bridge to drive to the East Bay. Any traffic on East Bayshore disproportionately affects East Palo Alto residents because during PM rush hour around 76% of trips on East Bayshore Rd east of Pulgas Ave terminates in East Palo Alto (Fig 2, row 1). I computed 76% as (1305 PM trips minus 310 cut-through volume) / 1305 trips. This data was obtained from Streetlight data in the fall of 2019, which is representative of current traffic since it was from a pre-pandemic year.

Traffic Light Cycle Analysis

On Thursday, January 23, 2025, I recorded drone video footage of the 3 intersections along East Bayshore Rd: at Pulgas Ave (East Palo Alto), Laura Ln (Palo Alto), and Embarcadero Rd (Palo Alto). It was immediately clear to me that the bottlenecking was at East Bayshore Rd & Laura Ln (Fig 3), which is the last traffic light intersection before drivers cross over a San Francisquito Creek bridge from Palo Alto to East Palo Alto and arrive at the East Bayshore Rd & Pulgas Ave intersection (Fig 4).

I am not a traffic engineer, but when watching the video in Fig 3 it is clear to me that this traffic signaling can be timed more effectively. Here is a table summarizing the amount of time and throughput of cars assigned to each portion of the cycle.

In the ~2-minute cycle of the traffic lights from 4:41pm to 4:43pm:

1. The left light turns green for 15 seconds from 2:00 to 2:15 for 2 cars making a left from East Bayshore southbound to Laura Ln.
2. The straight light turns green for 78 seconds from 2:15 to 3:33 for 29 cars (23 proceeding straight and 6 making a right onto Laura Ln).
3. The left light turns green for 20 seconds from 3:42 to 4:02 for 1 car making a left from Laura Ln to East Bayshore southbound.

Note that the times don't add up perfectly to 2 minutes since there are some all-red phases which I did not include since I can't see all traffic signals from the drone video footage.

In other cycles of Fig 3, I observed situations where 0 cars were in the intersection for extended periods of time. For instance, for 18 seconds from 1:42 to 2:00 in the video, there are 0 cars moving through the intersection. The traffic light appears to be green for cars on Laura Ln to make a left turn when there are 0 cars on Laura Ln. Meanwhile, cars are backed up on East Bayshore Road all the way to Embarcadero Rd. Would it not make more sense to use those 18 seconds towards moving more cars on East Bayshore Rd, rather than moving 0 cars on Laura Ln?

Driving Patterns After East Bayshore Rd & Laura Ln

In Fig 4, I fly the drone along East Bayshore Rd northbound from Laura Ln to Pulgas Ave in order to capture driving patterns downstream after drivers cross into East Palo Alto. I have observed that around 3 out of every 5 drivers turns right onto Pulgas Ave, while 2 out of every 5 drivers continues straight onto East Bayshore Rd.

I had previously observed inefficiencies where because there is only one lane, if the first car is waiting to continue straight along East Bayshore Rd northbound it blocks other drivers from turning right. In the grand scheme of East Bayshore Rd right now, this is not the bottleneck since drivers are being bottlenecked at East Bayshore Rd & Laura Ln. I have not observed cars backing up from East Bayshore Rd & Pulgas to East Bayshore Rd & Laura Ln, but I do observe cars backing up completely from East Bayshore Rd & Laura Ln to East Bayshore Rd & Embarcadero.

Solutions

Smart Cameras

I observed what appears to be a smart camera mounted on top of the signal light for cars on Laura Ln (Fig 5), but I do not think it is working properly based on results evidenced in the analysis section above. I would expect that as soon as no cars are seen on Laura Ln, the light phase should end prematurely and advance to the next phase.

Connecting Laura Ln and Geng Rd

What if a new road were added to connect Laura Ln and Geng Rd? 2100 Geng Road is a proposed townhome development in Palo Alto (SF Yimby). Could Palo Alto require the developer to build a road extending Laura Ln to Geng Rd? During PM rush hour, car usage on Laura Ln appears to be from USPS employees leaving work or parents driving into Laura Ln to pick up their children from the Silicon Valley International School, then turning left out of Laura Ln back onto East Bayshore Rd. Adding a connector road would actually make it easier for USPS employees and Silicon Valley International School parents to get to Embarcadero Road.

Connecting Geng Rd to Daphne Way

One day we might want a road from Geng Rd crossing the San Francisquito Creek to Daphne Way in the Gardens neighborhood of East Palo Alto. East Palo Alto residents might have concerns about cut-through traffic, but it would also help to eliminate the current situation where there is only one road (East Bayshore Rd) to get from the Embarcadero 101 exit to East Palo Alto.

Conclusion

In this blog post, I have shared inefficiencies I have observed with East Bayshore Rd & Laura Ln traffic signal light timing. I have proposed shortening the timing for cars on Laura Ln when no cars are detected, in order to prioritize moving more cars along East Bayshore Rd. The truth is that Palo Alto controls the entrance to East Palo Alto from the Embarcadero Rd exit, and any traffic light decisions they make impact East Palo Alto residents downstream.