As jurisdictions work to comply with Senate Bill (SB) 375, the Sustainable Communities and Climate Protection Act of 2008, it has become apparent that the traditional Level of Service (LOS) methodology for analyzing traffic impacts is working at cross purposes to SB 375. As a result, last year the legislature passed SB 743, which requires the Governor's Office of Planning and Research (OPR) to develop and adopt revised CEQA Guidelines that rely on a new methodology for assessment of traffic and transportation impacts. This article identifies the problems with the LOS methodology and describes OPR's proposed solution.
Among other provisions, SB 375 requires the State's 18 Metropolitan Planning Organizations (MPOs) to develop regional transportation plans that incorporate a "sustainable communities strategy" (SCS) that will enable the affected region to achieve the greenhouse gas (GHG) reduction goals established by Assembly Bill 32, passed in 2006. One of the key strategies for meeting these goals is the promotion of infill development. However, the LOS methodology for traffic impact analysis works against infill development.
LOS Shortcomings for Infill Development
Infill development actually loads relatively little vehicle travel onto the roadway network because it tends to be centrally located, so trips tend to be shorter. In addition, there are more public transit and pedestrian opportunities that provide alternatives to vehicle travel. However, infill development has a relatively greater impact on LOS. The environment is already quite developed and the roadway and intersection network is often already operating close to capacity. Consequently, a relatively small amount of traffic added by infill development can push the network over the LOS threshold.
By contrast, development of an outlying area can add three to four times the vehicle travel onto the network in comparison with infill development. But it will have a relatively low effect on LOS because outlying areas are less developed and it 
is less likely the road network is operating close to capacity. Furthermore, the traffic generated gets dispersed more the further it gets from the development, so by the time it reaches more congested areas, the additional traffic does not trigger LOS thresholds, or they are triggered at fewer intersections, even though the project may be contributing substantially to regional congestion.
LOS methodology can unfairly burden infill development, which may generate a relatively small amount of traffic, but because it is being added to a more congested area, it may exceed LOS thresholds of significance, leading to expensive mitigation requirements. As a result, the financial burden of transportation improvements is often loaded disproportionately onto infill developments.
Another problem with LOS analysis is that the focus is on intersections and roadways in close proximity to the project, but ignores regional effects. Even if more distant intersections are evaluated a project's impacts are minimized, due to the dispersion of traffic. It is also difficult to accurately predict how future traffic will be distributed, and errors will be reflected in the LOS results.
Mitigation for LOS impacts is also problematic, because it typically entails widening of intersections or roadways, which induces more traffic, ultimately exacerbating the problem it's intended to alleviate. Such improvements also increase adverse effects on pedestrians (e.g., greater crossing times with reduced safety) and reduce the livability of the areas flanking the widened streets. Furthermore, most jurisdictions are already struggling to maintain existing transportation facilities; expanding them to maintain LOS standards will only add to this burden.
New CEQA Guidelines
The shortcomings identified above have made it clear that the LOS approach to CEQA analysis has resulted in increased, rather than reduced, emissions of GHGs. SB 743 was passed to address this problem. Under SB 743, OPR must develop and adopt revised CEQA Guidelines that rely on a new methodology for assessment of traffic and transportation impacts. The new metric to be employed in traffic impact analysis must promote a reduction in GHGs and foster development of multi-modal transportation networks.
The revised guidelines must also be consistent with other State planning priorities, such as promotion of infill development. LOS standards that are promulgated in cities' and counties' general plans will not be preempted by the revised CEQA Guidelines.
Although SB 743 calls for a new traffic metric within Transit Priority Areas (TPAs), OPR is proposing to phase in the new metric to initially apply within TPAs, then to apply Statewide starting on January 1, 2016 (a date likely to change).
After evaluating a variety of alternatives, OPR identified vehicle miles traveled (VMT) as the preferred methodology in the draft guidelines that are currently out for review. This emerged as the superior approach for a number of reasons. VMT is easier to model and more accurate than LOS, and there are already many existing models available for calculating VMT. In fact, CEQA practitioners are already calculating VMT for the analysis of GHG impacts. It captures the full extent of vehicle travel, not just effects at isolated locations, and mitigation for impacts doesn't induce more vehicle travel. A much broader array of mitigation strategies is available, including bicycle and pedestrian improvements.
OPR issued draft revisions to the
CEQA Guidelines in August, which can be downloaded at: draft OPR Guidelines. (Comments are due on November 21.) Although they do not establish new thresholds of significance, they do suggest that projects located within a half-mile of public transit would not have a significant impact on traffic, and they explicitly eliminate vehicle delay as a significant impact. Impacts may also be less than significant if a project results in a reduction in areawide VMT. On the other hand, a project with greater per-capita VMT generation than the regional average may have a significant traffic impact. Transit projects, which could have had a significant impact on LOS, will be presumed to have a less-than-significant impact on VMT unless demonstrated otherwise.
The proposed guidelines include a new section on safety issues, particularly increased hazards to cyclists and pedestrians.
There are many other possible ramifications on traffic impact analysis that are beyond the scope of this summary.
