All public roads and streets are classified by function, which provides a basis for the selection of everything from design speed and geometric criteria to signs and guard rails. The Henry Hudson Parkway is classified as urban arterial. (Arterial provides the highest level of service at the greatest speed for the longest uninterrupted distance.)

• Typical minimum design speeds: 30-60 for flat terrain; 30-50 for rolling
• Note: Design speeds are higher than speed limits and frequently much higher than average speeds .

However AASHTO (Green Book) also says that roadways should be context-sensitive . For example, as land use density increases, the design speed typically decreases. (This is of course the opposite of what has happened along the Henry Hudson Parkway . Dense residential development around the parkway in South Riverdale required the addition of at-grade local access points, which have made it more of a boulevard. Likewise, the surging use of the waterfront esplanade by bicyclists and runners in Manhattan may change what is the appropriate speed for the adjacent roadway.)

Similarly, in areas that have significant historic interest or visual quality, a low design speed may be appropriate in recognition of lower average and operating speeds and the need to avoid affecting these historic or aesthetic resources.

FWHA offers the southern end of Rt. 9A in Manhattan (formerly the West Side Highway) as exemplary context-sensitive design in an urban arterial. 9A is classified with an allowable design speed under NYS DOT design criteria as high as 60 mph., but a design speed of 40 mph was used in order to preserve the design continuity and character of the route, in this case to better integrate the project into its surroundings. The new design incorporates extensive landscaping and separate bikeways and pedestrian walkways.(from FWHA “Flexibility in Highway Design”)

Our future vision of the Henry Hudson Parkway will have to look closely at the present and projected function of the road and its context. How much traffic is local and how much long-distance? How has local land use changed?