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Senate Bill 150-—California Takes Steps to Address the Land Use-Transportation Challenge in Reducing Greenhouse Gas Emissions

On October 10, 2017, California Governor Jerry Brown signed into law Senate Bill 150 (Allen), which aims to reduce greenhouse gas emissions by strengthening state transportation planning requirements. The bill establishes new requirements for setting regional greenhouse gas emission reduction targets and requires the California Air Resources Board (CARB) to monitor regions’ progress in attaining those targets.


SB 150 builds on and strengthens California’s existing laws for reducing vehicle miles traveled and improving transportation planning. In California, transportation planning is undertaken, in significant part, by eighteen federally designated Metropolitan Planning Organizations (MPOs). MPOs are federally funded regional organizations that are required by federal and state law to carry out various transportation planning functions. A core function of MPOs is development of a Regional Transportation Plan (RTP). In addition to satisfying federal requirements, RTPs must comply with California law, which directs that RTPs:

. . .be action-oriented and pragmatic, considering both the short-term and long-term future . . .[and]. . .present clear, concise policy guidance to local and state officials.

Since the passage in 2008 of California’s landmark land use planning law—SB 375—MPOs have been required to work closely with CARB in developing their RTPs. SB 375 directs CARB to set regional targets for reducing greenhouse gas emissions. These targets translate to the Sustainable Communities Strategy required to be included in RTPs. A Sustainable Communities Strategy models transportation projects, non-auto mobility strategies, and forecasted development patterns to determine their impacts on regional greenhouse gas emissions. Prior to adoption, an MPO must quantify the reduction in greenhouse gas emissions projected to be achieved by a Sustainable Communities Strategy and set forth the difference, if any, between the amount of that reduction and the regional target set by CARB. If an MPO’s Sustainable Communities Strategy is unable to achieve the emission reduction targets set by CARB, the MPO will prepare an Alternative Planning Strategy, which shows how targets would be achieved through alternative development patterns or transportation measures.

Under existing law, MPOs submit their adopted Sustainable Communities Strategy or Alternative Planning Strategy to CARB for review. The scope of CARB’s review, however, is limited. CARB may only accept or reject an MPO’s determination that the selected strategy would, if implemented, achieve regional emissions reduction targets. Sustainable Communities and Alternative Planning Strategies are expressly not subject to any state approval.

Mechanisms for Strengthening Regional Transportation Planning

SB 150 strengthens the transportation planning requirements established under SB 375 in two ways. First, the bill aligns regional greenhouse gas reduction targets with state targets established by SB 32 (2016). SB 32 set a target of reducing statewide greenhouse gas emissions to 80 percent below 1990 levels by 2050, and an interim target of reducing emissions to 40 percent below 1990 levels by 2030.

Second, the bill requires CARB to regularly report on the progress made by MPOs in meeting regional greenhouse gas emission reduction targets. Beginning September 1, 2018, and every four years thereafter, CARB must prepare and submit its report to identified legislative committees. The report must be prepared in consultation with MPOs and stakeholders, and must include changes to greenhouse gas emissions in each region and data-supported metrics for the strategies utilized to meet the targets, as well as a discussion of best practices and challenges faced by MPOs in meeting the targets.

 Conclusion and Implications

Although SB 150 requires only modest action, it tackles an ambitious problem. Transportation is the single largest contributor to greenhouse gas emissions in California. Land use and transportation planning play an instrumental role in curtailing those emissions. According to studies by CARB, if every Californian drove 1.6 miles less per day, by 2030 Californians would reduce enough greenhouse gas emissions to meet the state’s climate goals. SB 375, together with SB 150, bring California one-step closer to addressing the ever-vexing connection between transportation and land use.

(Shannon Morrissey, Hayley Siltanen)