SANDAG: Does smart growth reduce GHG emissions?

I’ve been looking through The San Diego Association of Governments’ (SANDAG) draft environmental impact report (EIR) for their regional transportation plan (RTP). For more information on why this is an important document, see our previous posts on SANDAG’s work, as well as our report on SB 375.  Both the RTP and the Draft EIR are currently open for comment.

In the draft EIR, SANDAG looks at the impact of several alternative scenarios.  It took a little digging, so I put together a table comparing the GHG emissions under each.  Here it is:

It’s worth noting that the table shows all GHG emissions, not just those due to transportation, but since transportation accounts for almost 50% of GHG emissions in San Diego County and since the RTP focuses on transportation, I’m assuming that transportation GHG emissions account for the differences between the scenarios. 

This table highlights two issues that I find troubling:

1. SB 375 is supposed to reduce GHG emissions below business as usual, but the “no project” alternative, which only includes the six highway projects and five transit projects that are already under construction in San Diego County, achieves the most GHG reductions of any scenario in 2050.  From an SB 375 standpoint, if the RTP doesn’t reduce GHG emissions compared to building nothing, why spend all this money—particularly on the many highway projects contained in the RTP.
2. Concentrating growth in existing downtowns and in mixed-use areas that are walkable and well-served by transit is a key strategy in reducing GHG emissions—in fact, this is one of the rationales for SB 375.  However, under SANDAG’s analysis, scenarios that assume a land use pattern that concentrates more housing and jobs in regional centers does not achieve additional reductions when using the same transportation network (compare Scenarios 2b and 2a, 3b and 3a, and 4 and 1).  According to SANDAG, fast-tracking transit also does not reduce emissions (compare Scenarios 3a and 1).

I can think of three possible explanations for these issues:

1. The tools that SANDAG uses to analyze these plans do not adequately account for smart growth land use strategies or for transit service, and instead focus overwhelmingly on moving vehicles, so they underestimate the potential of transit and land-use focused scenarios to reduce GHG emissions while overestimating the impact of the highway projects in the RTP. We’ve written previously on other aspects of the RTP that suggest that this is the case, and the Cleveland National Forest Foundation has concluded that SANDAG’s travel model does not adequately account for the potential for high-quality transit service to lure people away from driving, particularly for high income riders.
2. SANDAG’s current policies to improve transit and encourage smart growth are ineffective in reducing GHG emissions.  It could be that the RTP’s transit projects and the Smart Growth Concept Map focus more on achieving political goals by distributing transit services and growth equitably across the region instead of concentrating them in the areas where they make the most difference in order to reduce emissions and curb driving. 
3. The San Diego region is so sprawling and auto-dependent that even the most aggressive feasible transit improvements and land use changes only make a marginal difference in GHG emissions.

My guess is that all of the above play a role in the real explanation for why even the most ambitious smart growth scenarios perform so poorly, and why the no project alternative performs so well relative to the RTP. 

But that’s the problem: it’s just a guess, because there’s so much inconsistency and so little transparency with how we analyze GHG impacts.  The standards for reporting GHG emissions in RTPs and EIRs are different, so SANDAG’s RTP reports transportation GHG emissions in lbs. CO2/day, while the EIR focuses on overall GHG emissions in MMT CO2/year, so it’s difficult to compare the results.  And even though SANDAG’s EIR acknowledges that Scenario 5, the “slow growth” scenario, just outsources San Diego County’s transportation emissions to neighboring sprawl areas in Riverside County, the EIR still recognizes Scenario 5 as the environmentally preferable scenario, because it reduces environmental impacts--at least, in San Diego County--by exporting growth.  Clearly there’s a lot more work to be done in reconciling the EIR process with the state’s planning priorities.  The regional agencies that write RTPs often don’t help the situation by masking the real impact of these plans with aspirational language and specious performance measures.  For example, SANDAG’s RTP uses the percentage of growth located within its Urban Area Transit Strategy Study Area, which basically includes all of the urbanized area in the region, as an indicator of transportation-land use coordination, rather than, say, the percentage of new growth located within a half-mile of a high-frequency transit stop, which SB 375 uses as the definition for a transit priority project.

The resounding defeat of Proposition 23 during the last election confirmed Californians’ commitment to avoiding catastrophic climate change.  Though planning sustainable communities is crucial to meeting the state’s GHG reduction goals, a lot of people still don’t get the connection between how our cities are planned and how hot the world gets.  MPOs need to clearly and honestly communicate how RTPs progress toward GHG reduction targets.  The Air Resources Board and the other state agencies need to create consistent, effective standards for modeling and reporting GHG emissions, and for bringing the EIR process in line with these changes.  Only then will we get the kind of public awareness and support that lead to the federal transportation reforms that are ultimately necessary to spur a widespread shift to sustainable community planning.