When planning a residential driveway, most people visualize its surface. However, a driveway’s foundation should be the first consideration. Traffic loads, water and temperature are identified as basic causes of damage to driveway surfaces in 1993 research conducted by Ali Abdulla Al-Joaib. A driveway’s foundation must be stable or the surface will quickly deteriorate and can become hazardous, particularly to people with mobility disabilities.
Driveway construction raises specific safety issues for people with disabilities. A driveway’s slope should be less than 15% in order to avoid the dangers that arise from a steep incline. Curves in a driveway can lessen the impact of slope when a driveway must be placed in an area that is long and steep.
A driveway’s slope also determines water drainage. Accumulation of water on a driveway’s surface is especially dangerous to people with physical disabilities. Many homeowners are concerned about water’s harm to the driveway surface. Instead, people with disabilities need to consider the harm that a fall on a slippery surface can do to their bodies. In order to reduce the accumulation of water, driveways can be designed like a crown so that water drains toward the edges of soil and toward drainage channels. Driveways can also be graded at an angle that directs water toward street sewers.
Width is an important consideration in designing a driveway for someone with mobility disabilities. In some instances, a driveway must be wide enough to accommodate a van or another large vehicle that carries medical equipment. Additional width may be necessary to load and unload a wheelchair, a scooter or another power mobility vehicle.
A wide “turn-around” area for a car at the top of a driveway will help to position the car, and whatever medical equipment it contains, next to a home’s most accessible entrance. This area can alternatively be used for guest parking. (Teenage drivers should be clearly encouraged to park elsewhere, and walk!) If considerations of space or expenses make a wide “turn-around” impossible, the driveway should lead cars close to an accessible entrance that is not blocked by steps or other barriers.
A parking space should provide shelter for a person with disabilities. A garage offers the best protection from potential weather hazards such as rain, wind and snow. A large, sturdy awning is an alternative. Communication equipment, including a cell phone or car phone, can alert family members or caretakers to the arrival of a person with disability and a need for assistance.
Elevation of the cross-slope in the transitional areas between the driveway and the street is another important issue. The United States Department of Transportation reports that people who use mobility aids such as walkers and wheelchairs are placed in danger of falling when the cross slope of the area between the driveway and street is greater than 2%. A severe slope can cause a wheelchair to become destabilized, and can cause a pedestrian who is using assistive equipment to lose balance.
Driveway paving materials are grouped into two basic categories, solid-surfaces and aggregate -surfaces. Aggregate-surfaces, such as gravel and crushed shells, do not have flat surfaces. Asphalt is an example of a solid -surface material. It is flat and seamless when it is applied to a driveway’s surface. Concrete is also a solid-surface material when texture does not result from the application of gravel or other materials that create a rough, decorative surface. When used for driveways, both asphalt and concrete need a base of compacted gravel.
Recently, colors and tints have been developed for use with asphalt and concrete. Until this development, the color of asphalt confirmed Henry Ford’s assertion that “You can have it in any color you want, as long as it’s black.” Tar is used as an adhesive with asphalt and yields a black surface. Now, colors can be incorporated into asphalt during the mixing phase and tints can be applied with the sealant. The ivory surface of concrete driveways can also be tinted with color, and stain finishes are used. Concrete can also be etched, stamped and engraved to create texture and patterns.
Asphalt and concrete are relatively inexpensive materials. Both are durable materials that are safe choices for the driveways of people with physical disabilities. Installation of an asphalt driveway costs approximate $2.50-$4 per square foot. Asphalt is a petroleum based material, so the cost of asphalt is related to crude oil prices. The installation of concrete is more expensive, costing approximately $4-$6 per square foot. The costs will be greater for both materials if color is added or if patterns are added to concrete.
Maintenance should be carefully considered in the selection of driveway materials unless a homeowner is blessed with employees or— even less frequently!—with cooperative teenage children. Some driveway materials require diligent maintenance, and a poorly maintained surface can be dangerous for people who are vulnerable to falling. Approximately one out of three Americans who are over the age of 65 falls at least once each year.
Asphalt is less expensive to repair than concrete, but asphalt is less durable than concrete and more easily damaged. Asphalt needs more maintenance than concrete and requires more frequent sealing. Since asphalt is petroleum based, it is vulnerable to the solvent effects of brake fluid, gasoline and oil. Asphalt is also vulnerable to temperature. Asphalt becomes soft in heat and cracks in cold temperatures. Patching an asphalt driveway will maintain its structural integrity, but reveal differences in the dark black color of the patch when compared to the faded, grey color of the original asphalt. When cracks in asphalt are covered by a continuous application of new asphalt, the only evidence of repair in a resurfaced driveway is a fresh, new surface. Asphalt should be sealed 6-12 months after installation. Following the first sealing, asphalt should be sealed every 3-5 years. If an asphalt driveway is properly maintained, it can last for 20-30 years.
Concrete, a more pliable material than asphalt, is more responsive to the thaw-freeze cycles that characterize weather in the northern portion of the United States. Concrete driveways can last for 40-50 years without sealing, although sealing will improve appearance. Concrete, like asphalt, develops cracks. These cracks can be repaired, but the effects of weathering upon the concrete surrounding the repaired area make repairs apparent.
Solid-surface materials are safer than aggregate surfaces for people who use assistive equipment such as wheelchairs, canes, crutches and walkers. However, it is sometimes possible to safely use both solid-surface and aggregate-surface materials. For example, the installation of solid-surface accent materials in the parking pads at the end of gravel driveways creates an attractive and practical alternative for people with physical disabilities. A solid surface is especially helpful to people who use assistive equipment as they enter cars and exit from them.
Drainage also impacts choices between solid-surfaces and aggregate-surfaces. Aggregate surfaces such as gravel and shells allow water to reach the roots of surrounding plants and become re-absorbed. Solid-surface materials that create impermeable surfaces, such as asphalt and concrete, prevent water from being absorbed and can require drainage systems that re-direct run-off water.
Many materials are used as pavement for driveways. In addition to asphalt and concrete, popular surfaces include gravel, pavers, and shells.
Gravel is a natural material that comes in different sizes and colors. It is inexpensive when compared to asphalt, concrete and pavers, and is often chosen by homeowners who have long approaches to their houses. Although gravel is inexpensive to install, it requires ongoing maintenance because gravel is easily displaced from a driveway’s surface. The porous quality of gravel allows water to be absorbed by soil and roots, and pronounced run-off causes the erosion of surface stones. Driveway traffic and snow removal equipment also displace stones. A surface treatment of tar—called a “double-shot”— can be installed underneath gravel to counteract displacement. If tar is used, gravel replacement may not be necessary for 7-10 years. Gravel driveways need an annual application of herbicide to control the growth of vegetation.
Paver driveways are attractive and very resilient. Professional installation is comparatively expensive, and requires a great deal of manual work. Driveway pavers are made of interlocking materials such as brick and concrete, and installed over a foundation of crushed stone. Some paver driveways use basalt, an igneous rock. The edges of pavers are pliable so they do not develop the cracks frequently found in asphalt and concrete. Interlocking edges stabilize the pavers while giving them the flexibility necessary to withstand stressors such as erosion and freeze and thaw cycles. Pavers also protect the environment because they are permeable and encourage water’s re-absorption.
Crushed oyster, clam and scallop shells create an attractive driveway surface that is usually found in the Northeast. The handling of shells prior to installation is an important consideration. Shells must be thoroughly washed to avoid an unpleasant smell. Shells are permeable and create good drainage. Although comparatively expensive, shells are more affordable if purchased in large quantities. Shells become an increasing solid foundation for a driveway when crushed by cars into progressively smaller pieces.
All driveways require a stable soil foundation, and additional structural materials may be needed. In assessing the quality of soil, you may wish to consult with a soil engineer. Such a consultation is expensive and, if undertaken, should conclude with a written assessment and recommendations.
People who install and maintain residential driveways come from different backgrounds. They include experienced masons as well as people who have recently learned their trade on the job. A background search should be considered if it is legal in the state. Careful consideration should be given to experience that is validated by references because driveway installation requires sophisticated technical knowledge. Familiarity with the Americans with Disabilities Act Accessibility Guidelines (ADAAG) is an asset. Although compliance with the ADAAG is not required for driveways on private property, the ADAAG contains a wealth of helpful information. The intersection of a private, residential driveway with a public street will be guided by the ADAAG. The person who assumes responsibility for the installation or maintenance of a driveway should be familiar with building code specifications and municipal ordinances. The most widely recognized American building code is the International Building Code (IBC) published by the International Code Council. Inquiries should be made about construction permits, and a residential driveway permit should be received.
The equipment and materials used in driveway installation and maintenance can be hazardous. The Occupational Safety & Health Administration (OSHA) receives numerous reports of injuries. Appropriate topics for an interview include safety practices, supervision of workers, insurance and bonding. Protective equipment should be available and used.