What is Access Management?

The City of Lee’s Summit has developed a comprehensive Access Management Code to help balance allowing access to businesses along commercial corridors with providing safety to travelers throughout the city. Access management takes a comprehensive look at the access to businesses, parking and driveway connectivity, and the potential safety benefits to developing a system to simplify access to businesses and minimize the number of conflict points at driveways.

Managing access is important because each access along a roadway, whether a driveway or intersection, introduces the potential for conflict within the traffic stream. Access management also helps protect public investments in transportation by preserving safety and efficiency of traffic flow, thus reducing the need for costly and potentially invasive improvements.

Common access-related features that enhance safety and efficiency on the street system include:

• Driveways or side streets properly spaced in proximity to major intersections.
• Driveways or side streets spaced far enough apart that one does not affect the other.
• Presence of left- and right-turn lanes, when appropriate, to store turning vehicles and remove them from through traffic.
• Proper deceleration distance within left- or right-turn lanes.
• Traffic signals spaced to allow progression along a corridor

Figure 1 shows that as the amount of through traffic increases, access decreases. To manage access on public roadways, departments of transportation and municipalities focus on four core areas: 1) Access Planning, 2) Transportation Engineering, 3) Access Permitting, and 4) Coordination and Awareness. By focusing on implementing these four core areas, the benefits or goals of access management are achievable - safety, efficiency, and economic activity.

Benefits of Access Management

Managing access on roadways improves safety, efficiency, and economic activity. Motorists benefit from fewer decision points and traffic conflicts; pedestrians benefit by crossing fewer vehicle paths (fewer driveways); businesses benefit from a more efficient road system by expanding their market areas; and maintaining agencies (state, city or county) benefit from being able to maintain safety and efficiency on the roadway system while supporting economic activity.

Safety

A compelling benefit of access management is safety. National research consistently shows that about 40 percent of all crashes are access-related. The percentage is even higher in urban areas because there are more access points along urban roadways. As the number of access points along a roadway increases so do the number of conflict points. Conflict points occur where the paths of two or more roadway users cross. Each conflict point is a potential accident; conflict points can occur for any travel mode or between travel modes, such as when a vehicle crosses a pedestrian sidewalk. Figure 2 and Figure 3 identify vehicular conflict points and Figure 4 and Figure 5 identify pedestrian conflict points at sample intersections.

Figure 2. Vehicle conflict points at an intersection (without access management)

Figure 3. Vehicle conflict points in a directional median opening (managed access)

Figure 4. Pedestrian-vehicle and bicycle-vehicle conflict points at an intersection (without access management)

Figure 5. Pedestrian-vehicle and bicycle-vehicle conflict points in a directional median opening (managed access)

The previous graphics compare the number of conflict points at intersections with and without access management techniques. These illustrate that well-employed access management, depicted in Figure 4 and Figure 5, reduces the number of conflict points at the sample intersections.

Figure 6. Ratio of crash rate vs. access points per mile Source: Impacts of Access Management Techniques, NCHRP 420, TRB 1999

Figure 7. Travel speed vs. access density (local roads)

Source: Highway Capacity Manual 2010, Volume 2, Uninterrupted Flow, Exhibits 14 11 and 15-8, Transportation Research Board, 2010

Access Management and Retail

Retail businesses have traditionally believed that more access is better. Retailers worry that if it is hard for a potential customer to get to them, the customer will go elsewhere. As a result, retailers prefer access from a major arterial rather than a local street, with two driveways rather than one. When access management calls for fewer driveways, retail businesses can feel threatened. However, research has shown that access management can improve a site’s accessibility.

Several studies have shown that the number of driveways to a site has a minor influence on a customer’s decision to shop, especially when compared to the total travel time required to get to the site. Instead, factors such as the customer base, otherwise known as market area, are critical to business success. Market areas are determined by travel time and income levels. Although the average size of the market area varies by business type, the market area decreases as travel time increases. If a customer must spend excess time traveling along a congested corridor to and from a specific business, the customer will find a similar business with shorter travel time.