Roadways: Facility Selection

Facility Selection

Primary Guidance The facility type must reflect the corridor function(s) in an appropriate design year not to exceed the 20 year forecast. Practitioners are encouraged to start by evaluating less costly solutions such as operational strategies, network solutions or transportation system management techniques before selecting significant facility upgrades that entail major capital expenditures.

Discussion Design Year Major Capital Projects require the use of a Metropolitan Planning Organization (MPO) Travel Demand Model, or the Maryland Statewide Transportation Model (MSTM) both of which are based on a 20 year time horizon. System Preservation Projects may necessitate the use of a design year that supports more immediate traffic operation and/or safety needs, not to exceed 20 years. Functional Classification The facility must represent the appropriate balance between access and mobility for its intended purpose. The functional classification system developed by the Federal Highway Administration (FHWA) reflects the degree of local access and regional connectivity a roadway provides. The level of access control should reflect the official functional classification as well as the actual role that the roadway serves, which may vary along a roadway corridor. While there may be substantial flexibility in defining the level of access control for new roadways, the options may be substantially more complex or limited on projects that are modifying existing roadways. Roadway Users MDOT values the needs of all of its roadway users, including cars, trucks, bicyclists, and pedestrians. All user needs both along a roadway and across it should be considered. Truck and freight needs should consider existing truck volumes, identification of primary and secondary truck routes, and local and industry activity. Transit needs should consider coordination with transit operators when bus and/or rail service exists along a roadway. Pedestrian needs should consider locally adopted plans, existing pedestrian activity, proximity to pedestrian traffic generators, and network connectivity. Bicycle needs should consider locally adopted plans, existing bicycle activity, proximity to bicycle traffic generators, and network connectivity. Roadway Capacity and Operations Level of Service indicates general traffic capacity needs: When there is a design year Level of Service C(need graphic), or better, no additional capacity is needed. When there is a design year Level of Service D, or worse, additional capacity may be needed. Adding capacity that creates failing conditions upstream, or downstream, of proposed improvements should be avoided. Other performance measures may be needed to develop solutions that address specific project needs. Additional measures may pinpoint specific capacity and operational needs more accurately. Additional measures should be considered in certain urban areas and constrained areas where level of service improvements may be cost prohibitive, physically infeasible, and/or impractical due to other project limitations. Performance measures such as vehicular queueing, network delay, latent demand, travel time, person throughput, and Planning Time Index can also be used to guide roadway capacity decisions.

See Also

• Roadways: Vertical Alignment