"ROADWAY SAFETY AND 'CLEAR ZONES',"
Chapter 9.5 of Roadway Fundamentals for Municipal Officials
a workshop presented by the Maine Local Roads Center, Maine Department of Transportation, 1995

This publication is presented for "Classroom Use Only."  Its intended use is to stimulate and aid in discussion and role playing within a classroom setting.

9.5 ROADWAY SAFETY AND "CLEAR ZONES"

Municipalities are required to provide safe and convenient roadway facilities. These facilities consist of both the travel portion of the road and the adjoining median and/or shoulder areas. This section will highlight a few areas where roadway and roadside safety can be improved.

In the 1980's a study revealed that approximately 60% of fatal accidents involved only one motor vehicle. In about 70% of these accidents, the vehicle left the roadway and either overturned or collided with a fixed object.

With limited resources, municipalities must carefully consider where to spend funds available for roadside safety improvements. One way to choose high priority projects for safety improvement is locations where accidents have occurred. There are two good sources of information regarding accident data... local law enforcement agencies and the MDOT Planning Division Office at 287-2942. These two sources should be able to help identify critical areas within your municipality.

Additionally, Road Commissioners/Engineers can decide where to improve safety based on personal, staff and public observation and input. Municipal road officials and employees drive over their systems regularly. By spending so much time on the roads, these people observe certain situations and conditions that are dangerous and need improvements. The public often provides information about safety hazards. The input comes in the form of phone calls, letters, a board member and verbal complaints to a highway department employee.

Run-off-the-road and collision-with-fixed-object accidents are the greatest source of fatalities on local roads. Clear zone improvement is an important part of any safety program. A clear zone can be defined as the unobstructed, relatively flat area provided beyond the edge of the traveled way for recovery of errant vehicles. The travel way is the portion of the roadway not including shoulders. It is desirable to provide a roadside clear of hazardous objects or conditions for a distance consistent with speed, traffic volume and geometric conditions of the site. The greater the width of the clear zone, the greater element of safety provided.

Design standards from the AASHTO Roadside Design Guide for new low-speed rural roads indicate that a minimum clear zone of ten feet is desirable, This is often difficult or impossible to achieve on existing low-volume roads. However, clear zone widths should be increased where there is significant danger to the driving public, especially where evidenced by recurring accidents. When planning the construction of new roads, every effort should be made to establish a minimum ten-foot clear zone.

Clear zone hazards include natural and man-made objects. Examples of natural hazards include trees, rock outcroppings, steep embankments or drop-offs. Man-made hazards include utility poles, mailboxes, culvert headwalls, deep ditches, bridge rails and bridge supports. Ironically, even the guiderail and sign systems we install to protect the public against natural hazards and to provide information often become hazards.

Several factors affect the degree of danger a fixed object presents to the motorist who collides with it.

1. Distance from the edge-of-travel way to the object

2. The rigidity and shape of the object - a bridge abutment poses more threat than a two inch sapling

3. Geometric characteristics of the roadway - width, sidestopes, horizontal and vertical curves

Knowledge of these factors, common sense and good judgment are your guide when evaluating potential roadside hazards. Once an appropriate clear zone has been determined for a road, then potential hazards can be identified. The following actions are suggested, in order of desirability, to deal with the hazards identified:

Eliminate the potential hazard - flatten slopes or remove trees

Move the fixed objects to safer locations - place utility poles farther from the roadway

Safety-treat objects that must remain - change signposts to breakaway, install U.S. Postal Service approved mailboxes

Protect the hazard - install a guiderail, crash cushion or other device to prevent an "out-of-control" vehicle from reaching the hazard

Alert the driver to the hazard - install signs or delineators

9.5.3 Guiderail

The primary purpose of guiderail is to prevent vel-licles from striking a fixed object or terrain feature that is considered more hazardous than striking the guiderail itself The need for a guiderafl will be based on the relative severity between impacting aguiderau and impacting the hazard. The decision for barrier protection should be made on the site-specific factors, including traffic volume, speed, geometry and proximity of hazard to travel lane. Before installing guiderafl, attempts should be made to remove the hazard if possible. The Maine D. 0. T Hig@ Design Guide presents the types of roadside guiderails which are approved for use in Maine. The requirements for each type of system and a description of each is also included as is a more detailed discussion of when guiderails are warranted.

Signing can be improved in two general areas.

1. Signs can be added to alert drivers to dangerous road conditions. Also, signs that have lost reflectivity should be replaced.

2. Consider improvements to protect the public from hazards created by sign hardware. This can be done by using breakaway or less-rigid devices.

Placement of signs should follow the concept of positive guidance which suggests that drivers operating at a generally safe speed should be warned whenever the condition ahead is such that they will not be able to react to a hazard in time to adjust their driving safely. Another important idea is that the level of signing should be consistent along a particular segment of highway. Be sure that your signing creates a consistent expectation for drivers - no surprises!

9.5.5 Mailboxes

Mailboxes -are designed to hold mail and protect-it from the elements. Many property owners have gone to great lengths to customize the appearance of their mailboxes. This "art" takes endless forms from plows, concrete arms, welded chains which appear to defy gravity, and steel I-bearns to name a few.

If we consider the ways to achieve an adequate clear zone, the two most effective methods are to eliminate the potential hazard and to move the fixed object to a safer location. For most mailbox installations, this is difficult to achieve. To serve their intended function, mailboxes must be easily accessible to the delivery vehicle. This necessitates placing most rural mailboxes close to the paved roadway surface. If these mailboxes are located within the roadway clear zone they should be designed, located and installed so that they pose the least hazard to the user and the motorist. Both the landowner placing a hazardous mailbox and the municipality that controls the right-of-way bear liability for accidents that may occur. The following sample letter from the Maine Municipal Association can be used to inform landowners of unacceptable mail box assemblies and the options for removal.

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TO:

FR: Selectmen, Town of _______________

RE: Hazardous mailbox fixture

DATE:

Dear _______________________

Your mailbox is located within the legal right-of-way of the ___________ street/road. The fixture holding your mailbox constitutes a deadly fixed object due to its size, inimobility, composition and/or mass. It presents a life-threatening danger to motorists, road maintenance workers and other persons using the road, and must therefore be removed. See 23 MRSA §§2701 and 3651 et seq.

You are hereby notified to remove the maillbox fixture on or before____________ (date). If the mailbox fixture has not been removed by that date, the Town will have it removed and you will be billed for the costs of removal.

Thank you for your cooperation.

 

copy to: local postmaster

9.5.6 Utilities

The best way to manage the siting or moving of utilities is to adopt a local law that establishes rules and penalties for accommodation of utilities within the public right-of-way. Once this law has been adopted you should develop a permit that fists all the rules and penalties in detail and send a copy with a cover letter to each utility that operates in your municipality. For both above ground and below ground utilities, it is important to specify a minimum distance from the edge of pavement or traveled way for placement. For below ground utilities, you should also specify the depth of placement.

9.5.7 Trees

Trees can be extremely hazardous depending on their size, type, location and condition. Trees located within the right-of-way and near the roadway are of the greatest concern. Trees can also cause additional problems during the winter if they block sunlight from reaching snow or ice covered pavements,

Tree removal can often create problems with landowners and the general public. Trees can greatly enhance the aesthetic value of roadways and properties. They can also serve to reduce the visual and noise impacts of vehicles and roadways. People in general are against tree removal practices.

Dealing with trees as a liability consideration must be done with caution and care, balancing the above concerns to the extent possible. It is important to discuss the concerns and options with abutting landowners before proceeding with any type of tree removal operation.

Concrete fountains, planters and other decorative items are also a liability concern. Depending on their size, shape, location and rigidity such items may need to be considered for removal from a liability point-of-view. When used, their location and design should be carefully considered and altered if necessary. Such items typically add an aesthetic value only and do not improve the functional operation of the roadway system.