Design Level of Service

General
Level of service (LOS) is a measure of traffic flow and congestion. As defined in the
Highway Capacity Manual
published by the Transportation Research Board, the LOS is a qualitative measure describing operational conditions within a traffic stream – generally described in terms of such factors as speed and travel time, freedom to maneuver, traffic interruptions, comfort and convenience and safety. Selecting a design LOS is a conscientious attempt to reasonably accommodate traffic in the design year. The definition of a LOS is described in more detail in the
LGPM Guide
.
Federal Requirements
  1. 23 CFR §625.2
    – Requires plans and specifications for projects on the national highway system (NHS) to provide for a facility that will adequately serve the existing and planned future traffic of the highway in a manner conducive to safety, durability and economy of maintenance, and to conform to the particular needs of each locality.
  2. 23 CFR §625.3(a)(2)
    – Requires federally funded projects not on the NHS to be designed in accordance with State directives and design standards.
State Requirements
  1. 43 TAC §§5.59
    ,
    15.56
    ,
    26.33
    and
    27.56
    – Requires projects to be designed in accordance with TxDOT manuals, procedures, standards and guidelines. For RMA, toll and pass-through financed projects, preliminary design information must be sent to TxDOT for review and approval when the design is approximately 30 percent complete.
Required Practices
The LG must select a design level of service and submit it to TxDOT for concurrence. The
LGPM Guide
provides more information on this process.