Housing as Transportation Solution?


Palo Alto has the highest in-commuting rate in the region and the second highest in the country after Manhattan.  Downtown areas are busy and it’s hard to find parking. On Tuesday, the Comprehensive Plan Citizen Advisory Committee (CAC) will be discussing talking about the policies and programs to help address the city’s transportation challenges. As we think about the future of transportation, here are some thoughts for the committee to consider…


Housing as a transportation solution

A big reason we see so much in-commuting is because Palo Alto has many more jobs than homes.  There are ~100,000 jobs, and under 30,000 homes in the city.  One major option to reduce in-commuting is to provide more places for workers to live.  

When Mountain View did its environmental review for its General Plan, it studied an option to add housing in the North Bayshore area where Google and LinkedIn are.  The study found that the option with more housing would generate fewer car trips.   Not everyone wants to live near where they work, and not everyone who would live in North Bayshore housing would work there either. But in general, giving people more options to live near work results in less commuting and less driving overall.

Area Plans + Trip Caps

To make more housing a transportation solution, area or precise plans, are required to reduce transportation impacts. In Mountain View and San Mateo, “precise plans” often include trip caps and policies to reduce car trips,  crafted based on the characteristics of the area.  For the PA Comprehensive Plan, there is an opportunity to create area plans, and then holistically define trip goals, transit accessibility, parking strategies based on the available transportation options for each area.  Housing can be part of the equation for reducing trips as well.

For example, the downtown PA Transportation Management Association (TMA) has robust new data about commute patterns for its ~10,000 workers (a year ago, we didn’t even know how many people worked downtown)! The TMA has already identified pilot programs to reduce car commuting, and has more proposals in the queue. For Stanford Research Park, Stanford’s transportation group is already working on ways to reduce car-commuting for the over 20,000 workers in that area.    


Trip cap strategies show results.  Stanford’s trip cap in 2000 resulted in reducing the drive-alone rate from 72% to under 50% in 2013.  Mountain View’s trip cap for North Bayshore has led LinkedIn to propose programs for its new headquarters where only a third of employees will drive to work.

The focus on specific areas is helpful, because each area has distinctive program needs. Downtown Palo Alto is walking distance from Caltrain, so there’s no need for a shuttle to take workers from the train - but there are many service workers who live in East Palo Alto who’d benefit from improved route and hours for the EPA shuttle.   On the other hand, business at Stanford Research Park are 1-3 miles from the train, and would require different strategies to reduce trips (transit shuttles, ride sharing, bike infrastructure, etc).

Metrics for Better Mobility

To drive transportation choices in Palo Alto in the coming decades, we need better ways to measure all types of travel.  Traditionally, cities have used automobile level of service (LOS) as the main metric to monitor and attempt to relieve congestion.  Auto LOS measures the number of seconds a car is delayed at an intersection during peak periods, then assigns grades to different wait times (A is <10 seconds, F is >80 seconds).

LOS has been the main metric used under the California Environmental Quality Act to measure the environmental impact of traffic. However, in 2013, the state passed SB743, to move away from using auto LOS as the measure for environmental impact.  Instead, a suggested metric is vehicle miles travelled (VMT) per capita. Cities already have to measure vehicle miles travelled (VMT) in order to measure reduction of greenhouse gas (GHG) emissions, which they are required to do in order to comply with AB32 (reduce GHG to 1990 levels by 2020)

Palo Alto needs to follow state rules in conducting environmental reviews, but can set local policies.  While LOS is a useful tool (you want to know if drivers are stuck at an intersection for too long) it has serious weaknesses as the ONLY metric and the only way to get a better LOS grade at any intersection is to expand road capacity.

  • Traditionally, cities have “mitigated” wait times at specific intersections by widening roads and intersections.  This makes walking and bicycling less safe and less appealing (imagine wide South Bay intersections), and leads to more driving.  Palo Alto wisely adopted a general policy to avoid road-widening - but has fallen short on implementation to increase modes of non-auto transportation (no accountability for car trip reduction goals, underpriced parking, stagnant investment in bike infrastructure)

  • LOS focuses on individual intersections, making it is a poor metric to measure other solutions.  For example, most of the traffic at Page Mill is coming to Stanford Research Park. The County recommends widening Page Mill, but by contrast, Stanford's Transportation Dept believes that it can be more effective at relieving congestion by with programs to reduce trips, including shuttles to Caltrain, long-distance shuttles, etc.  Such programs can significantly reduce VMT- but only indirectly affect LOS.

  • Using LOS as the main metric tends to discourage infill development.  Greenfield development in exurban areas shows lower LOS impact, while development in an already-built area can push congestion over a threshold.  However, infill housing in an area with a housing shortage is likely to reduce overall car trips and vehicle miles travelled, even if wait times at a specific intersection stay the same or increase somewhat.

  • VMT can also provide clues toward ways to reduce local trips while improving quality of life.  In general, over 50% of car trips are short non-commute trips.  Better shuttle and bike connections could help reduce congestion and parking demand by giving more people good choices to avoid driving for shopping, errands, etc.

Palo Alto should still monitor LOS to ensure intersections don't have significant delays.  But VMT is a better overall tool to measure and reduce the impacts of traffic.  Driving will remain an important option for many - the opportunity is to reduce the share of driving; so people who do need to drive can have an easier time driving and parking. 


Be the first to comment

Please check your e-mail for a link to activate your account.

Ask City Council to Make Housing a Priority!


get updates