Transportation Plan - 2009, amended

6.3 Roadway Design Guidance Access Management

Access management is defined as “…the systematic control of the location, spacing, de- sign, and operation of driveways, median openings, interchanges, and street connections to a roadway,” as well as other design factors such as local/state policies, spacing of traffic signals, and median treatment types. 1 Managing roadway access from driveways and cross-streets has become increasingly important as funds to widen major roadways on the secondary transportation system have dwindled. Core reasons to enforce access management include reduction of accidents, improving bicycling conditions, providing safer pedestrian pathways, increasing business market area / access, and extending the serviceable life of roadways and roadway capacity. It is important to manage the access of roadways before the land around them becomes developed, as retrofitting roadways is often extremely costly and controversial compared to protecting access management before a roadway becomes saturated with driveways and street intersections. Figure 6.7 identifies typical actions that should be taken and the common effects on road- way performance and business activity (often a concern with retrofitting access controls). This table complements the one on the following page that describes various roadways and treatments. Among the important factors to consider are that additional, frequent, and poorly designed driveways can decrease travel speeds by five to 10 miles per hour, and accidents (as well as associated travel delays during accidents) can increase by 40% or more if proper access management techniques are not followed. Business failure rates along unmanaged corridors are also higher than along well-managed roads.

Figure 6.7 Principles of Access Management Principle Action(s)

Researched Effects

Maintain a Strong Roadway and Intersection Hierarchy

Reduce Signals / Mile: 4.0 6.0 8.0 Access Points / Mile: 10 20 30

Increase in Travel Time Compared to 2.0:

16% 29% 39%

Limit Direct Access to Major Roadways

Reduction in Free-Flow Speed (mph): 2.5 5.0 7.5 10 42% reduction in crashes 59% reduction in delay 57,500 gallons of fuel reduction per mile 25% - 50% reduction in crashes (four-lane roads) 67% reduction in total crashes 35% reduction in accidents 30% reduction in vehicular delay 15%-57% reduction in crashes (four-lane roads) 20% - 40% reduction in crashes

40 or more

Favor Through Movements Separate and Limit Points of Conflict

Prohibit on-street parking

Long signal spacing

Separate Turning Moves (esp. left turns)

Add left-turn bay Raised divider separating lefts from through traffic Install median Install continuous, two-way left-turn lane Replace TWLTL with a median

Use Medians

Support Internal and External Connectivity

Increase driveway illumination

42% reduction in crashes

Roadway Hierarchy Roadways are typically described by just two functions: the mobility that they provide to move vehicular (especially motorized vehicles) traffic quickly, and the degree to which the roadway provides access to adjacent lands. In North Carolina, roadways are frequently given classifications that describe their place in the hierarchy of streets. The following cat- egories of street are generally recognized by transportation professionals, along with some of their major characteristics (Figure 6.8). Notice that some of the values overlap between categories, indicating that the road- way’s definition is perhaps determined by plans for it instead of simply a matter of how wide it is or how fast the posted speed limit. This overlap also suggests that other factors besides mobility and accessibility can play significant roles in the design and development of roads, shown below in no particular order. • Number of large trucks that use the roadway • Degree of peak traffic congestion (compared to how much traffic the roadway generally carries throughout the day) • Topography, water courses, wetlands, ridgelines, floodplains, and other natural features shape roadways • The crossings of other roadways, rail lines, and even bicycle/pedestrian accommo- dations influence roadway design, width, and speed for short intervals • Amount of through traffic compared to traffic that has destinations or origins im- mediately adjacent to the road • History of accidents on the roadway and similar roadways • The kinds of land uses that border the roadway – commercial, residential, distribu- tion, and so forth • The users of the road – would more cyclists or pedestrians use the road if there were better provisions for them; • How constrained is the public right-of-way for the road, and how does that influ- ence design and construction costs • Are there utilities that use the same right-of-way as the road – water, sewer, electri- cal, cable, or fiber optic • The access to / from the roadway currently controlled by law, policy, design or some other means? 1 Transportation Research Board, “Access Management Manual.” Committee on Access Manage- ment, Washington, DC, 2003.

The street network.

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6 Design Guidance