Road Connectivity
roadconnectivity.png 
​Providing a strong connected network of roads and pedestrian facilities can help distribute traffic, reduce travel distances and times, improve routing for transit and reduce walking distances. Good connectivity also provides better routing opportunities for emergency and delivery (solid waste, recycling, mail) vehicles. All of these effects can play a positive role in reducing congestion on the street network.
 
Connectivity is achieved by providing connections within individual developments, between developments and by having a well planned collector road network to compliment the arterial highway network. Connectivity of an area can be measured using a connectivity index - commonly defined as the ratio of links to nodes. To achieve network connectivity, one guideline is to have arterials spaced approximately ½ mile apart and collectors every ¼ mile.
 
References
KYTC Street Connectivity Model Ordinance
The term "street connectivity" suggests a system of streets with multiple routes and connections serving the same origins and destinations. Connectivity not only relates to the number of intersections along a segment of street, but how an entire area is connected by the transportation system.
KYTC Street Connectivity Model Ordinance.pdf

Roadway Connectivity (VTPI)
Connectivity refers to the density of connections in path or road network and the directness of links. A well-connected road or path network has many short links, numerous intersections, and minimal dead-ends (cul-de-sacs). As connectivity increases, travel distances decrease and route options increase, allowing more direct travel between destinations, creating a more accessible and resilient system.
Roadway Connectivity (VTPI)

Measuring Network Connectivity
Advocates of New Urbanist and neo-traditional planning concepts include street connectivity as a key component for good neighborhood design. Street networks that are more grid-like are preferred over networks that include many cul-de-sacs and long blocks, thus increasing distances between destinations.
Measuring Network Connectivity

Connectivity Measures (Rutgers University)
Recently, the field of planning has seen a rise in both academic and popular interest in New Urbanism and transit-oriented development (TOD). This has placed a renewed emphasis on higher densities, mixed land uses, pedestrian friendly development, and the coordination of land use and transportation, which, in turn, has created a need for methods to empirically quantify and measure urban form.
Connectivity Measures (Rutgers University)

Connectivity (SRTS)
A network of streets, sidewalks, bicycle lanes and paths in which all parts are well-connected to each other reduces the distance children have to travel to get from home to school, allows for the use of more local streets rather than major roadways and provides a greater choice of routes to travel to and from school.
Safe Routes to School

Connectivity Model Ordinance (WSDOT)
Street connectivity ordinances are designed to increase the number of street connections in a neighborhood and to improve the directness of routes. The purpose is to achieve an open street network that provides multiple routes to and from destinations.
Connectivity Model Ordinance (WSDOT).pdfConnectivity Model Ordinance (WSDOT).pdf

Cary, NC Memo on Connectivity
The purposes of the ordinances are to support the creation of a highly connected transportation system within the Town, in order to provide choices for drivers, bicyclists, and pedestrians; promote walking and cycling; connect neighborhoods to each other and to local destinations such as schools, parks, and shopping centers...
Cary NC on Connectivity.pdfCary NC on Connectivity.pdf

Knightdale, NC Development Ordinance
Knightdale, North Carolina Development Ordinance