CHAPTER 7 ACCESS MANAGEMENT Background Principles of Access Management Hennepin County Transportation Systems Plan (HC-TSP)
Chapter 7 Access Management 7.1 Background Access management has become an important subject as transportation professionals grapple with the challenges of increasing congestion and deteriorating roadway operations. The goal of managing access is to achieve an optimal balance between what is needed for safe and efficient roadway operations versus the need to provide access to adjacent properties and businesses. The term access management is applied to a number of measures that can be used to enhance a roadway's safety and its ability to move vehicular traffic through management and control of access points to the roadway. These measures include: Limiting the number of driveway access points to decrease turning conflicts Location of entrance or access points further from adjacent intersections Providing sufficient spacing between intersecting streets Spacing traffic signals to optimize traffic flow Implementing sight distance guidelines to improve safety Use of channelization to preclude selected turning conflicts HC TSP 7-1 Chapter 7 Access Management
The purpose of a county access management program is to; 1. Enhance the county's ability to provide a safe roadway system 2. Assist in efficiently moving traffic 3. Support on-site circulation patterns that minimize impacts to the county roadway system 4. Provide safe and reasonable access to adjacent properties This chapter discusses the basis behind the evaluation and regulation of access to county roadways. Access Management Guidelines are included in the Support Documents that explain the entrance / driveway permitting process and the design guidelines used for access construction. 7.2 Principles of Access Management Through State Statute (160.18, Subd. 3), the State of Minnesota has granted regulatory authority to agencies that have roadway and highway responsibilities. The statute says: The owner or occupant of property abutting upon a public highway, having a right of direct private access thereto, may provide such other or additional means of ingress from and egress to the highway as will facilitate the efficient use of the property for a particular lawful purpose, subject to reasonable regulation by and permit from the road authority as is necessary to prevent interference with the construction, maintenance and safe use of the highway and its appurtenances and the public use thereof. These agencies include Mn/DOT, counties and cities. The regulatory authority includes the issuance of entrance / driveway permits for properties located immediately adjacent to the roadway. Minnesota Rules (Chapter 8810.4100 to 8810.5600) have been established to implement the statute for trunk highways to establish certain optimum design specifications for driveways providing a means of ingress and egress from private property located along and adjacent to the right-of-way of the trunk highway system of the State of Minnesota. Historically, these operating rules for Mn/DOT have also been used as a basis of the access permitting process for Hennepin County. In 2002, Mn/DOT released Technical Memorandum No. 02-10-IM-01 that describes the agency s Access Management Policies and Spacing Guidelines. Hennepin County s Access Management Guidelines are consistent with Mn/DOT s Technical Memorandum and the county s guidelines also address the access management issues described in that memorandum. The HC-TSP includes modified access spacing guidelines from those developed in 2000 to account for the more urban context. In practice, it is recognized that spacing guidelines need a more flexible application in urban areas. The Minnesota Rules noted above and HC TSP 7-2 Chapter 7 Access Management
the Mn/DOT Access Management Technical Memorandum are included within the county access management guidelines in the Support Documents (enclosed CD). Access management has been practiced by roadway agencies for many years, usually with regard to protecting principal arterials such as interstate highways, expressways and other state highways. For important highway corridors, Mn/DOT has purchased access control rights along highway right-of-ways. This tool is being used less frequently today due to the associated high costs. Hennepin County has also exercised access management techniques on its roadway system through a variety of practices. The entrance permitting process and preliminary review of developments / plats have been significant tools for access management. Most driveways and street entrances constructed on the county system since the 1960's required permits governing their location and configuration or they have been built in conjunction with a construction plan for upgrading a roadway. The county has processed approximately 4,000 entrance permits on its roadway system to date. 7.2.1 Enhance County s Ability to Provide a Safe Roadway System One of the primary motivating factors to implementing access management techniques is to improve the safety of the roadway. In recent years, the states of Colorado and Florida have been leaders in examining the safety benefits of reduced access points to a roadway. Studies have consistently found that access management techniques reduce crashes. In fact, studies by the Institute of Transportation Engineers have found that 10 to 15 percent of arterial roadway crashes can be attributed to driveway conflicting movements. Mn/DOT has also been examining the statistical relationship between vehicular crashes and highway access. Based on a statistical analysis of state roadways, Mn/DOT has found that: There is a significant correlation between crash rates and access density for all state highway categories. Roadway segments with the lowest access density have below average crash rates. The correlation between crash rates and access density does not appear to be significantly affected by other characteristics such as traffic volume, speed limit, or type of access. Crash data within Hennepin County was examined and found to mirror other states and Mn/DOT s findings. The segment data of Hennepin County was plotted to examine the relationship between the crash rates and the access spacing density. Exhibit 7-1shows the plot of the data. It appears that crash rates increase rapidly as the density of access increases (or the average spacing decreases). Based on the limited observations, the number of crashes appears to increase rapidly as the average spacing drops below 500 feet. HC TSP 7-3 Chapter 7 Access Management
Exhibit 7-1 Hennepin County Crash Rates as Function of Access Spacing Driveway spacing is critical since it is suspected that driveway related crashes are under-reported. Crash reports may fail to link the crash to certain extenuating circumstances such as: Rear-end crashes upstream from a driveway related to slowing vehicles trying to make a right turn into a driveway. Rear-end crashes downstream from a driveway due to entering vehicles which have not yet accelerated to roadway speed. Sideswipe crashes in which a vehicle changes lanes behind another vehicle that is preparing to enter a driveway. Collisions involving two vehicles using closely spaced adjacent driveways or when the driveway is close to an intersection. 7.2.2Assist in Efficiently Moving Traffic Good access management can positively affect the roadway mobility function while decreasing the number of vehicle conflicts. A vehicle conflict is defined as a point where two moving vehicle paths cross (see Exhibit 7-2). The studies mentioned above have found that the traffic capacity of a road decreases markedly as turning traffic is added from driveways. HC TSP 7-4 Chapter 7 Access Management
Exhibit 7-2 Types of Vehicle Conflicts The roadway capacity can be profoundly affected by reducing the turning vehicle conflicts. Estimates based on empirical studies performed by the Institute of Transportation Engineers in the 1970s of four-lane undivided arterials found that the capacity decreases approximately 1 percent for every 2 percent of added turning traffic into the connecting driveways. The terms access and mobility are frequently used interchangeably, but they represent two distinct concepts. Roads can function in two ways; they may provide access to properties and they provide mobility, the ability to get from one place to another. Access to properties is needed at both ends of a trip. Mobility involves the speed and freedom of movement along the path of each trip. Most roadways serve both functions to some degree, and this planned degree of access and mobility determines the road's functional classification. The four levels of functional classification are: Table 7-1 Relationship between Functional Classification, Mobility and Land Access Roadway Functional Class Level of Mobility Level of Land Access Principal Arterials Highest None Minor Arterials High Limited Collector Streets Moderate Moderate Local Streets Low Highest HC TSP 7-5 Chapter 7 Access Management
In an efficient roadway network, these four types of roadways function together in a complementary fashion to serve the needs of the traveling public. The proportion of arterials, collectors and local streets must be of a proper balance to achieve a roadway system that operates effectively. Modifications made to a roadway's function without consideration of the complete roadway system will tend to undermine the operations of the system. For example, a system comprised of all local streets would not move traffic very well. Conversely, a system of too many arterials would not provide adequate land access. The county roadway system is primarily made up of minor arterial type roadways that should primarily provide a mobility function with minimal direct land access. In the urban area, this function often comes into conflict with the perceived function that some county roads are neighborhood streets. In some cases, local residents may favor lowering speed limits and other "traffic calming" techniques to limit the facility's mobility function. These traffic calming techniques are in direct conflict with the objective of increasing the road mobility aspect, and providing for efficient movement of goods and services along key high volume routes within a community. 7.2.3 Support On-Site Circulation Patterns that Minimize Impacts to County Roadway System The pattern of land development can have a significant impact on a roadway s operations. If adjacent properties develop piecemeal with no underlying plan, numerous individual driveways will result thus degrading the roadway operations. Access management should begin early, before an area develops or when redevelopment alternatives are being investigated. Long range corridor plans can result in a reduction of access points needed, and also provide for more efficient land subdivision. Exhibit 7-3 illustrates an example of how land development patterns can affect the access spacing. HC TSP 7-6 Chapter 7 Access Management
Exhibit 7-3 Access Management Needs to be Considered as Part of Land Subdivision 7.2.4 Provide Safe and Reasonable Access to Adjacent Properties Individual property owner s desires for convenient roadway access needs to be balanced with the public need to provide as safe a roadway as possible. The proper balance between these competing objectives can be obtained through long range planning that includes the designation of land uses and the establishment of future roadway concepts. The county is obligated to provide access to a parcel of land if the parcel would otherwise be landlocked and there is no other alternative available. This problem can be avoided by thoughtful design at the time of site planning. Generally, local street systems need to be configured so that properties have their access oriented to the local streets which then provide connections to the collector street system and ultimately the minor arterial roadway system. 7.2.5 Access Management Experience Experience with the implementation of the access management techniques and guidelines from the 2000 HC-TSP has found that for large developments, this area is a high-profile and highly charged area. Generally, most residents, developers and city staff accept the principles behind access management the challenges appear when these principles are applied to specific cases. Issues of property rights, business livelihood, and neighborhood livability all surface during development reviews of medium to large-sized developments or redevelopments. HC TSP 7-7 Chapter 7 Access Management
Observations of the process to date have found that the challenges occur in two main areas: process and communication. Process challenges include: Results of piece-mealed development Difficulty of monitoring the status of recommendations Communication challenges include: Lack of resident awareness of previous decisions Coordination issues between agencies and departments By far, the most difficult challenge has been dealing with the piece-mealed development process whereby some land is developed, but critical exception parcels are left behind or the phasing is such that first-in residents become a constituency that forms against allowing the other future planned phases of the development, thereby focusing development access to the county roadway system instead of the local street system. One planning tool that could be used more to assist with these types of issues is the ghost plat a shadow layout of how the whole area is anticipated to develop including land use types and future street system alignments. Although adjustments would likely be needed over time as conditions change, these ghost plats can help identify the shape and orientation of the development and help to determine where major intersections should be placed. This type of coordination has occurred with a number of cities within Hennepin County. 7.2.6 Access Spacing Guidelines In the 2000 HC-TSP Hennepin County adopted access spacing guidelines that were based on national and local research and were consistent with those used by Mn/DOT. For this 2030 HC-TSP, the guidelines have been refined and the charts have been reformatted to classify the access based on the type of land use being served as shown in Table 7-2. Further information on the guidelines and the entrance/driveway permitting process is contained in the Access Management Guidelines document included in the Support Documents CD in the map pocket of this report. HC TSP 7-8 Chapter 7 Access Management
Table 7-2 Access Types Access Type Single Family Residential & Agricultural Field Entrance Low Volume Driveway (< or = 500 vehicles per day) High Volume Driveway (> 500 vehicles per day) Low Volume Public Street (< or = 2,500 ADT) High Volume Public Street (> 2,500 ADT) Description Access to single family residential dwellings and unimproved field entrances for agricultural land. Small commercial, industrial and institutional developments and small residential complexes having trip generation less than 1,000 trips per day. Large commercial, industrial and institutional developments, shopping centers, office parks, colleges, and large residential subdivisions having trip generation greater than 1,000 trips per day. Streets and roadways with a projected 20-year ADT less than 2,500 vehicles per day. Streets / roadways with a projected 20-year ADT greater than (or equal to) 2,500 vehicles per day. For each access type, the guidelines provide recommended spacing of access points for rural and urban settings. Urban is defined as being location within the 2000 Metropolitan Urban Service Area (MUSA) boundary as defined by the Metropolitan Council. An Urban Core category was added to the 2000 HC-TSP guidelines in response to comments on the plan and experience administering the guidelines over the last few years. The Urban Core recognizes the constraints of fully developed areas that have a tightly woven network of public streets with relatively short block lengths of 300-660 feet. This category is similar to that used by Mn/DOT in its guidelines, and is meant for cities such as Minneapolis and the first ring suburbs. In addition the spacing is categorized by the functional classification of minor arterial and collector street. The functional classification is defined in the Hennepin County Transportation Systems Plan (2030 HC-TSP) and in individual city Comprehensive Plans. For proposed private entrances, the trip generation characteristics of a development can generally be estimated using the Institute of Transportation Engineer s Trip Generation Manual. Developments which are not categorized by the ITE Trip Generation Manual can often be estimated based on similar type developments or using specific data from other sources. During the review process for development site plans or access permits, consideration will be given to existing limitations for retrofitting projects and for the differences in flexibility of development in a suburban or rural environment versus redevelopment projects in the denser urban environment. All driveway and street access must be set back a minimum of 300 feet from busy HC TSP 7-9 Chapter 7 Access Management
intersections in order to maintain unhindered operations for the intersection turn lanes. Accesses should conform to the recommended spacing under the appropriate category. Access requests that do not meet the recommended spacing may be required to provide additional justification, evaluation, and analysis. The guidelines allow for a closer spacing on divided roadways if the access is a partial movement access meaning that only a few movements are allowed (example: right-in / right-out, or right-in only). In most cases, partial accesses are not applicable to undivided roadways without medians since channelizing islands have not been found to be an effective method of precluding wrong-way vehicle movements. Further information on the guidelines and the entrance / driveway permitting process is contained in the Access Management Guidelines on the 2030 HC-TSP Support Documents CD. 7.2.7 Implementation Actions A Plat Review Committee was established in January 1999 as part of the early implementation of the 2000 HC-TSP recommendations. Since this time, the committee has reviewed hundreds of preliminary plats, site / concept plans, and access requests. As part of the platting process, the committee has recommended to the cities and obtained the dedication of over 40 acres of right-of-way along county roadways. This land has a value of almost $11 million in today s dollars. Other recommendations from the 2000 HC-TSP that have been implemented include the development of a Plat Review brochure outlining the process and information needs, and the update of the county s 1967 driveway specifications. HC TSP 7-10 Chapter 7 Access Management