Automobile Level of Service in Transit Station Areas: A Survey of Current Practice
Interest in fostering development around rail transit stations has many jurisdictions considering the best ways to plan for multiple modes of transportation in these areas. Efforts to increase the intensity and mix of development around rail station areas are intended to capitalize on the public investment in rail transit, boost ridership, increase rail access to homes and businesses, create environments that support the use of alternative modes, and foster economic development. In many areas, the increased density creates concerns about how to balance the needs of automobile users with pedestrians, cyclists and transit users, particularly as development is phased in over time.
Traditional approaches to evaluating transportation system performance include level of service (LOS) measures, which are detailed in the Highway Capacity Manual. The most commonly used measure is the automobile level of service at the intersection level, which is based on volume to capacity ratios translated into levels of delay experienced by motorists. The acceptable performance standards for specific facilities are outlined in comprehensive plans and new development that degrades conditions below these set standards typically must scale back the project or mitigate the future congestion, usually through expansions in capacity, such as adding lanes or turning bays, or through transportation system management solutions, including adjustments to signal timing and phasing.
Requiring a high automobile performance standard can create obstacles to approving more compact, mixed use development, which concentrates trip generators in one place and have the potential to increase the number of trips in the area, including those made by automobile. The supply-side mitigations can also degrade the transportation environment for other modes of travel. For example, widening intersections or increasing the green time on traffic signals can create more difficult conditions for pedestrians. On the other hand, many infill and transit-oriented development (TOD) projects cannot rely on transit and foot traffic alone to be financially viable, particularly in their early stages of development and some concessions to the automobile traffic may be necessary. The challenge for many transportation planners is finding the appropriate balance between the various transportation system users.
Since the passage of ISTEA, many communities have advanced the practice of planning for a multi-modal transportation system. They have promoted alternative modes of transportation through various policies, including land use and design approaches, and have subsequently developed methods and standards for evaluating performance or service of pedestrian, cycling and transit environment. Despite recent efforts to develop multimodal measures of level of service, comprehensive, quantitative approaches that combine these service measures in a planning methodology that permit examination of tradeoffs that incur with different investment decisions are lacking. However, many communities are reevaluating the standards they set for automobile level of service in areas where alternative mode use is high, such as central business districts, infill areas, special generators, and transit oriented development. The lessons learned from these communities can be helpful in the development of measures and methods to TODs in Fairfax County and the Washington, DC region as a whole.
This report provides an overview of how several communities around the nation have considered automobile congestion within transit station areas, locations designated for transit oriented development or infill projects, or near areas targeted for specific development policies.
Our primary aim is to synthesize the state of the practice with respect to planning for automobile congestion within rail transit station areas and to develop recommendations for level of service standards for transit oriented development areas for Fairfax County Virginia. To do this, we reviewed the comprehensive plans for many communities with rail transit stations in their jurisdiction and other documents that outline the performance standards for automobile congestion. In addition, we interviewed planners and engineers working for these jurisdictions to understand the rationale for these standards and experiences with them.
To date, we have identified over twenty jurisdictions that have defined a specific level of service threshold within or near transit oriented development or some other similar mixed use, infill, or higher density development. These jurisdictions are largely located within California, in part, due to legislation at the state level (California Environmental Quality Act) that forces local governments to consider the nexus between transportation impacts of land development. We have drawn heavily upon published documents that include comprehensive plans, overlay zoning codes, and local reports.
Traditional methods of evaluating level of service using the Highway Capacity Manual have been under scrutiny for their inability to consider all modes of transportation, the piecemeal application of these standards, bias toward greenfields development projects, and the typical approaches that expand automobile capacity when these performance standards are not met. Jurisdictions have dealt with these limitations in a variety of ways and the findings of this report are summarized in Table 1.
The development of a multimodal level of service standards or measures based upon person-capacity, not just vehicular capacity, has been discussed as an alternative approach1; however, these methods have yet to see widespread adoption. Most locations concerned about this issue have lowered their performance standards for automobile congestion in areas where higher density development is desired or exempt development from meeting the LOS standard altogether. In others, the level of service concept is applied area-wide, rather than focusing on particular intersections. This allows for some congestion at the intersection level but the total throughput of a corridor or area is the most critical measure of interest. In a very few cases, alternative performance measures have been employed, abandoning the level of service concept altogether.
The findings here are organized as follows. First, we discuss how regulation at the state level has impacted consideration of level of service for different development areas. Then, we review the policies for jurisdictions that permit some deviation from their LOS standards for development within TOD or infill areas. Jurisdictions that promote alternatives to LOS or multimodal measures are reviewed. Finally, locations that do not have a specific LOS policy for TOD but do have rail transit present are discussed.