The CSS process allows designers to balance the need for capacity with other stakeholder goals. Reframing the challenge as moving people (not vehicles) allows for innovative and cost effective solutions to be realized.
Selection of a design level of service represents an important design control that is a choice of the project team. This choice should be made carefully, with the input and understanding of the community and all stakeholders …” “A flexible or context-sensitive approach for a project acknowledges the need to tailor the level of service to other design controls and constraints within the context of the project’s purpose and need.”
Source: A Guide for Achieving Flexibility in Highway Design (AASHTO)
The AASHTO Green Book and most DOTs provide guidelines for selection of LOS, but these are guidelines only. In the Green Book’s own words: “Choice of an appropriate LOS for design is properly left to the highway designer.” DOTs are not required to file design exceptions, nor are they subject to tort liability concerns, for selecting a LOS lower than the recommended guidelines. Rather, selection of a target LOS is a policy decision and is based on a particular jurisdiction’s philosophy on whether or not to accept congestion.
Source: Traffic Projections and Levels of Service Targets (PPS)
