Access Management of Driveways in Cities & Towns

Article by Nicholas R. Jones, P.E., with excerpts from Local and Rural Road Safety Briefing Sheets: Access Management http://www.safety.fhwa.dot.gov

As smaller cities and towns grow into larger cities and towns and traffic increases on their roads, city management often wishes that they had used access management principles before their roads became so congested. Managing the location and future location of driveways is important as traffic becomes denser on the roadways.

Local and residential roads are designed to provide the driver access to the road system. Each town usually has regulations on how many driveways can be connected within each lot. Collector roads are designed to provide more mobility and less access from driveways and generally have many local street connections, but fewer driveway accesses. Arterial roads generally have limited driveway access and are designed to provide more traffic volumes. Several suggestions from the Local and Rural Road Safety Briefing Sheets by FHWA are as follows:

Good access management can accomplish the following:

Reduce crashes and crash potential
Improve access to properties
Provide appropriate drainage
Maintain travel efficiency and related economic benefit.
Preserve public investment in the highway infrastructure

In rural areas, driveways are often obscured by sharp curves, steep hills, trees, and buildings limit sight distance available for drivers entering or leaving the roadway, as well as, drivers traveling on the roadway. Drivers entering the roadway from a driveway need a clear line of sight in each direction to identify approaching vehicles. Additionally, drivers traveling on the roadway must be able to see vehicles entering the roadway from driveways in order to slow or even stop if necessary. Drivers slowing or stopping to leave the roadway at a driveway create a risk to following drivers who must slow, and possibly stop, as the lead vehicle turns onto the driveway.

Location

Driveways should be located where highway alignment and grades are favorable. Driveways should not be located near sharp curves, steep grades, or points that unnecessarily interfere with the free and safe movement of traffic. If possible, it is preferable so that a driveway intersect the main roadway at right angles (90 degrees).

Turning Radius

The turning radius should be between 5 and 20 feet for typical automobiles. Larger trucks and vehicles pulling trailers make wide turns and require a larger turning radius of between 30 and 60 feet. Careful consideration of the turning radius is necessary for urbanized areas with expected pedestrians. Large turning radii can create wide driveways and may require pedestrian refuge islands.

Other Considerations

A high number of driveway entrances along a roadway should be avoided to minimize conflicts. Consider combining driveways into a single entrance at the safest location when possible. Lighting the driveway entrance may be helpful vehicles entering the roadway, as well as, making the driveway more visible to traffic on the roadway. Avoid driveways near intersections that may conflict with turning movements. A few simple plan review steps can avoid future congestion and crashes along important corridors making your life easier down the road.

Source: http://www.utahltap.org/newsletter/archive/UtahLTAP_2014_Summer.pdf