Chapter 3.1
Development Patterns and Infill

• ALL
• Remove Code Barriers
• Create Incentives
• Fill Regulatory Gaps

Shared Driveways to Avoid Fragmentation of Habitat

INTRODUCTION

Many local governments require subdivisions to provide individual driveways from each lot to the nearest public street or road. These requirements result in more roadways that fragment wildlife habitat and may lead developers to create less dense developments with multiple access points as well as larger lot sizes, which consumes more land and wildlife habitat. Local governments can modify these requirements and enact subdivision regulations that allow shared driveways to encourage development layouts that consume less wildlife habitat.

These ordinances typically set forth design requirements and standards for when shared driveways may and must be used to access lots.[1] Additionally, these ordinances should specify the legal status and permitted uses of the driveway. Local governments may require the shared driveway to be centered on the property line bordering the two lots sharing the drive and may require owners to file a maintenance agreement detailing when and how maintenance will be performed on the driveway.[2] Alternatively, local governments may allow the driveway to be placed exclusively on one property and then file an access easement, giving the other owner a perpetual right to use the driveway for accessing their property. Local governments may use a hybrid approach in which the owners must file both an easement and a maintenance agreement for the shared driveway before the project is approved.[3]

EFFECTS

As stated above, individual lot access driveways require more space and material to construct than shared driveways. This means more habitat fragmentation and may lead  developers to create larger lots to accommodate the increased space requirements, and the development consumes more land that was previously undeveloped. Undeveloped land, also known as greenspace, provides valuable services to local governments.[4] These services include air purification, water purification, soil retention, and recreation.[5] When greenspace is destroyed, the cost of replacing these services shifts to the municipality. Greenspace may also consist of suitable wildlife habitat or corridors. Therefore, destroying greenspace may harm a jurisdiction’s overall biodiversity.[6]

Shared driveways also allow buildings to be grouped closer together in some instances, creating a more dense development. These denser developments still inevitably consume greenspace, but usually at a lower rate than developments that are required to have individual lot access driveways. Therefore, a development that utilizes shared driveways helps preserve greenspace and the benefits it provides to the local government.

Additionally, the use of shared driveways has other side benefits such as reduction in stormwater management costs.[7] Driveways, particularly in newly developed urban areas, are typically required to be made out of an impervious surface, meaning that water cannot filter through the driveway into the ground.[8] The water then runs off onto streets and the local stormwater management system and may be contaminated with oil, gas residue, salt, and other sediments.[9] Shared driveways reduce the cost of stormwater management by essentially cutting the number of driveways in half or more, thereby reducing the amount of runoff a local government must address.

EXAMPLES

Surprise, AZ

The City of Surprise declares that it will require the use of shared driveways wherever feasible.[10] Exceptions include when the two adjoining properties have conflicting uses, such as a residence and a business, or where a shared driveway is impractical because of topography or parcel configuration.[11] Where a shared driveway is required, the developer or owner must file both a “joint use private access easement” and a private maintenance agreement with the City as a condition of the project being approved.[12] These instruments give both owners the legal right to use the driveway, and help ensure that conflicts do not arise over the responsibility of maintaining the driveway. The City may, but is not obligated to, assist the developer in acquiring these instruments by negotiation or by using its power of condemnation.[13] However, if the City does assist in acquiring these rights, the developer is required to reimburse the city for the total cost of doing so.[14]

To view the provisions, see Surprise, AZ, Code of Ordinances Sec. 122-121 (h) (1) (f) (2009).

Austin, TX

Austin allows the use of shared driveways, but places additional requirements on the developer if the driveway will serve more than three residences.[15] Notably, the developer must post a financial surety for the construction of the driveway prior to approval of the project.[16] The City must inspect and approve of the constructed driveway before the surety will be released back to the developer.[17] The driveway must be designed by a professional engineer, and must at least meet the construction standards for private roadways.[18] The developer must also obtain approval to use a shared driveway from the fire departments in the area, to ensure that firefighting services can reach the proposed development without being unnecessarily delayed.[19] The developer must also use restrictive covenants that prohibit the landowners from parking on the driveway, or in the alternate, make the driveway at least 24 feet wide.[20] Finally, the developer must post signs at the driveway entrance indicating that it is a private drive, and that the city is not responsible for maintenance.[21] The regulations ensure that the driveway is well constructed, large enough to accommodate emergency vehicles, not obstructed by parked cars, and ensure that the public will not harass the City if the driveway is in disrepair.

To view the provisions, see Austin, TX, Transportation Criteria Manual § 5.3.1 (H) (1)-(6) (current through 2018).

ADDITIONAL EXAMPLES

Ironwood, MI, Code of Ordinances Sec. 34-547 (b) (3) (2011) (limiting properties to one access drive per parcel in a high traffic zone, and requiring owners of shared driveways to file a access and maintenance agreement with the City).

Powhatan Cty., VA, Code of Ordinances Sec. 68-175 (e) (5) (e) (2016) (requiring shared driveways when necessary to limit direct vehicular access to arterial streets).

Westlake, TX, Code of Ordinances Sec. 36-44 (d) (2) (e) (2011) (requiring all applications for a shared driveway to be accompanied by a shared access easement, and giving dimensional standards for the size of the easement).