Access management

From PlanningWiki

Access management is a group of strategies, tools, and techniques that work to improve the safety and efficiency of roads – not by adding lanes but by controlling where vehicles can enter, leave and cross a road.

Access management is a process for providing access to land development, while preserving traffic flow on surrounding roadways in terms of safety, capacity, and speed. This is done by managing location, design and operation of driveways, median openings, and street connections along a road. It also includes use of dedicated turn lanes or bypass lanes, to keep turning vehicles from blocking through traffic.

Access management is used to improve vehicular and pedestrian safety, maintain road capacity and reduce congestion, and enhance community character and aesthetics.

By maintaining the capacity and level of service of the road, access management protects the substantial public investment in transportation, and reduces the need for expensive improvements. Studies conducted in Florida and Colorado suggest that poor spacing, design, and location of driveways lower average travel speed, and improvements in access management can increase roadway capacity. Research has also shown that access management helps reduce the rate and severity of traffic accidents. Good definition and spacing of driveways also improves pedestrian and bicycle safety, by reducing the potential for conflicts with turning vehicles.

From a land development perspective, access management requirements further the orderly layout and use of land and help discourage poor subdivision and site design. The quality of site access is also important to the success of a development project. The Urban Land Institute Shopping Center Development Handbook warns that poorly designed entrances and exits not only present a traffic hazard, but also cause congestion that can create a poor image of the center. Reducing the number and frequency of driveways and median openings also improves the appearance of major corridors. More land is freed for landscaping, the visual dominance of paved areas is reduced, and scenic or environmental features can be protected. access management requires coordination of land use and transportation objectives. Communities can address the interdependence of land division and access and add access management regulations in road design or zoning regulations. Access management techniques usually include the following:

• Regulation of driveway spacing, corner clearance, and sight distance.
• Increased minimum lot frontage and setback requirements along thoroughfares.
• Restriction on the number of driveways for existing lots, and consolidating access wherever possible.
• Requirements for driveway design elements and conditions requiring their use.
• Requiring internal connections, unified circulation and parking plans between adjacent properties.
• Treating properties under the same ownership and those developed as a unified project as one property for the purpose of access control.
• Continuous curb cuts are unattractive and unsafe, and make it difficult to tell where a road ends and a parking area begins.
• Using frontage and rearage roads to serve as a common access drive for properties along a corridor.
• Restriction of flag lots and regulate private roads and access easements.
• Reducing commercial strip zoning and promoting mixed use and flexible zoning.
• Reducing administrative lot split subdivisions to prevent access and right-of-way problems.

Contents 1 Driveway location and design 2 Driveway number and spacing 3 Corner clearance 4 Joint and cross access 5 Frontage and rearage roads 6 Medians 7 Implementation 8 Best practice 9 Definitions 10 Discussion 11 References 12 See also 13 External links

Driveway location and design

Driveway location and design affects the ability of a driver to safely and easily enter and exit a site. If not properly placed, exiting vehicles may be unable to see oncoming vehicles and motorists on the Redundant driveways add points of conflict that make traffic patterns unpredictable, increase the risk of accidents, and contribute to traffic delays. roadway, or not have adequate time to stop. If driveways are too narrow or have a small turning radius, vehicles will be unable to maneuver quickly and easily off the road. If the turning radius and width are very wide, fast maneuvers on and off the site pose safety hazards for pedestrians, bicycles, and vehicles. Without an adequate throat or stacking lane, vehicles may block traffic while waiting to enter a site, or block parking rows while waiting to leave.

Driveway number and spacing

Decreasing the number of driveways and increasing their spacing can increase safety and traffic flow.

Many businesses along major arterials, even those on narrow lots, have two or more driveways. Business owners sometimes perceive these driveways as offering easier, more convenient access to potential customers, but they increase the number of conflict points along the road, and reduce the spacing between driveways. Redundant driveways increase the points where traffic can back up and accidents can occur.

Reasonable spacing between driveways is also important to the safety and capacity of a road, as well as the appearance of a corridor. Managing driveway spacing is essential on roads intended for higher speeds. At higher speeds drivers have less time and distance to react to unexpected situations. In most access management codes, the minimum distance between driveways increases, based on the classification, design speed, and traffic volume of the road.

Corner clearance

Driveways located too close to intersections are dangerous, and add to traffic congestion.

Corner clearance is the distance from an intersection to the nearest driveway. Corner clearance standards, and restrictions on driveways in acceleration, deceleration and right turn lanes, preserve good traffic operations at intersections, and the safety and convenience of access to corner properties. Having a larger minimum lot size requirement for corner lots will protect the development potential and market value of corner properties. It will also help assure that these properties do not experience access problems as traffic volumes grow.

Joint and cross access

Shared or cross-access driveways can reduce the number of driveways accessing the road, and also cut the amount of short vehicle trips on the road.

Joint and cross access involves connecting neighboring properties, and consolidating driveways serving more than one property. This allows vehicles to circulate between adjacent businesses without having to re-enter the road. Joint access is also used to connect major developments, reduce the number of driveways, and increase driveway spacing where highway frontage has been subdivided into small lots. This allows more intensive development of a corridor, while maintaining traffic operations and safe and convenient access to businesses.

In many communities, larger parcels are often developed as a unified site, with joint and cross access planned from the start, even if the site will be subdivided into several commercial lots. In areas where good access management techniques are not practiced, land is usually subdivided and developed incrementally over a long period, with no unified plan for a site. Each of the resulting lots is developed individually, with no coordination of access.

One way that joint access can be implemented is by prohibiting direct access from outparcels and lots that are carved from larger lots. Instead, the owner of the original parcel must provide access rights from the old lot to the new. If the original host lot is not immediately developed, the developer of the newer lot may be allowed a temporary driveway, which would be closed when the original lot is developed. The easement or access agreement is recorded with the property records, along with a joint maintenance agreement, and an agreement to close the temporary driveway when the joint access system is complete. As an alternative, property owners can also be required to create a binding joint access and cross easement plan before subdividing their property.

For new development on new and existing lots, access rights and stub-out drive aisles to adjacent parcels can be required by zoning code parking requirements, along with the appropriate access easements and/or agreements. For lots that are developed, creating stub-out driveways and recording access easements and/or agreements would be required if the business or use on the property changed, or as a condition of a building permit for major expansion or renovation.

Because access is shared, it will also be easier to share parking areas. Zoning codes should be amended to allow reduced a lower number of parking spaces for a use if access is shared.

Another option is to declare a cross access corridor on the zoning map for parts of the corridor where retail and commercial development will be intense, along with design requirements; for instance, the travel corridor must extend the entire length of each block it serves, or at least 1,000 feet (300 meters) of linear frontage along a street, be able to accommodate two-way traffic, and have a design speed of 10 MPH (15 KPH).

Frontage and rearage roads

Frontage and rearage roads can reduce the number of driveways and conflict points along a road, but they can also be expensive to build.

Frontage roads can be useful for eliminating driveway connections; they can serve almost as a collective driveway to a number of properties. However, if not carefully managed, frontage roads can create operational problems at intersections, especially when combined with high traffic volumes associated with commuter routes and commercial areas. If frontage roads connect close to major intersections, severe congestion, long delays, and high accident rates could result.

Frontage roads can be difficult and very expensive to implement in developed areas, because the right-of-way is relatively narrow, and they could eliminate the parking area for many businesses. Frontage roads would also create a very wide traffic corridor that would be visually intimidating, and detract from the exurban character of the township.

Rearage roads, also called backage roads, function much like frontage roads, only they are placed behind areas to be developed. Rearage roads allow for a greater distance between their connection with cross streets and the intersection of those cross streets, eliminating problems with congestion. Rearage roads can be implemented over time by acquiring right-of-way – a process that may be costly – or through a method similar to the cross access corridor scheme described in the previous section.

Medians

Medians can control the location and reduce the number of left-hand turn points, and eliminate congestion caused by stopped cars turning from the passing lane.

Raised or grassy medians in the center of a road separate opposing lanes of traffic and restrict turning and crossing movements. Studies from around the nation show that roads with raised medians are safer than those with undivided thoroughfares or center two-way left turn lanes, where traffic is far less predictable, and left hand turns can create accident- and congestion-prone conflict points.

As with driveways, the spacing and design of median openings is important to the safe and efficient operation of a major arterial. Safety benefits are reduced where median openings have inadequate storage – the length of the stacking area for cars waiting to turn – or are too close together, increasing the number of conflict points.

Medians also provide a refuge for pedestrians and bicyclists crossing a road, and can provide visual appeal and relief if they are landscaped. Some communities have “adopt-a-median” programs, where a small sponsorship sign is displayed to identify a business or group that paid to landscape and maintain a stretch of median.

Implementation

Best practice

Definitions

Access management is a formal, structured program to coordinate and maintain the safe and efficient use of the arterial street system, while providing necessary vehicular access to adjacent lands.
– John L. Heilman, P.E

(Access management is) the control of access along surface (nonfreeway) streets—primarily arterials and major collectors. The concept concentrates on restricting the number of direct accesses to major surface streets, providing reasonable indirect access, effectively designing driveways, and enforcing safe and efficient spacing and location of driveways.
– Ronald K. Giguere, Federal Highway Administration

Access management is a set of proven techniques that can help reduce traffic congestion, preserve the flow of traffic, improve traffic safety, prevent crashes, preserve existing road capacity and preserve investment in roads by managing the location, design and type of access to property.
– Reducing Traffic Congestion and Improving Traffic Safety in Michigan Communities: The Access Management Guidebook

(Access management is) a process for providing access to land development, while preserving the safety and capacity of the transportation system.
– Vermont Highway System Policy Plan

Discussion

• Cyburbia Forums Transportation planning subforum

References

• Madison Township US 20 Corridor Plan, Lake County (Ohio) Planning Commission (2006)
• Economic Impacts of Access Management, Kristine M. Williams, AICP, Center for Urban Transportation Research, University of South Florida, 2000

See also

External links