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Roadside Obstacle / High Hazard Removal

Obstruction Removal

One of the missions of the DPW&T is to help reduce the frequency and severity of motor vehicle crashes by improving the safety of St. Mary's County Roadways. To accomplish this, improving the physical characteristics of roads which affect safety; design and engineering; lighting, maintenance, and signage; safeguards for highway workers, bicyclists and pedestrians; and protection from roadside hazards are required. Hitting a tree, utility pole, or bridge support accounts for one out of four motor vehicle deaths on U.S. roads, especially on secondary roads. Authority is provided under Section 109-2 of the St. Mary's County Code. Grading, tree removal, cut and fill operations, improvements to sight distance, lessening of ditch fore-slopes, utility pole relocations, bridge approach treatment and culvert extensions are just a few of the activities performed in an effort to remove roadside obstacles in high hazard locations and to improve dangerous roadway conditions. Sight distance improvements and removal of roadside hazards are necessary to assure the County's roadways are safely and effectively maintained. In March 1998, the Department requested all school bus and emergency response organizations (fire, rescue and advanced life support) provide the Department with a comprehensive listing of potential safety related concerns along the County's roadways.

Potholes and Sinkholes

Potholes: A pothole is a bowl-shaped hole caused by localized disintegration of the pavement surface.

There are several different ways that potholes form, but the most common cause of potholes is due to moisture seeping into small cracks in the pavement. Moisture, most often rainwater, sinks through small cracks in old or weakened asphalt. The water is then soaked up by the mixture of rock, gravel and sand that supports the roadway. This is why potholes can appear to develop overnight and after periods of heavy rain. Overtime, vehicles passing over the road force water deeper through the soggy roadbed, eventually eroding parts of it. As the roadbed continues to erode the asphalt begins to sink into the eroded portions and eventually cracks under the continued impact of vehicle tires. Other contributing factors in the creation of potholes are high traffic volumes, roadbed base failure, drainage problems near or under the roadway, petroleum products, such as diesel or gasoline spilling on the asphalt, frost boils, and utility failures.

Potholes can also be caused by the continued deterioration of another type of distress, such as alligator cracking, raveling, poor drainage, or a failed patch after pieces of the original pavement surface have been dislodged. Weak spots in the base or sub-grade or the severity of the surrounding distress accelerate potholes. Potholes are considered a structural form of deterioration. Potholes may also result from winter weather patterns that consist of many freeze-thaw cycles - They typically form when moisture seeps into cracks in the surface of a road and freezes, causing it to expand. When the ice thaws that space is left empty, and combined with frequent or heavy traffic over the crack, causes the asphalt to crack and fail.


A sinkhole is a hole that reaches past the base of the roadway. Sinkholes are generally larger and deeper than potholes. They are usually caused by a source of water moving under the pavement, such as a damaged / abandoned storm sewer pipe, broken water lines, underground springs or even a utility conduit trench. The water causes the soil / dirt below the base to wash away, creating a void under the pavement, has washed away, causing the upper surfaces of the pavement to eventually give way and fall through. Sinkholes appear suddenly and unannounced as holes in our pavement, even though they are caused by events, years in the making. Sinkholes are generally repaired with similar means and methods as potholes. However, in most cases, sinkholes are more intense to repair due to the fact the sub-grade and sub-base materials must be replaced prior to patching. When sinkholes are big, they can be hazardous to drivers and pedestrians.

The Department of Public Works & Transportation encourages the public to report significant sink holes on County maintained roadways immediately. This partnership with the community is a great example of our continuing efforts to improve our customer service. You can also contact our Pothole Hotline at (301) 475-4200 or access our 311 online reporting system.

Potholes are created when water seeps into cracks in the surface of the roadway and combined with the vibration of tires over the cracks, or freeze/thaw action causes the asphalt to fail. That is why there are more potholes after it rains or during the winter season. Potholes are also created when the roadway is stressed by trucks and buses, which can cause a movement of the subsurface. Once there is a weak spot, the section of road will eventually fail. Highway maintenance crews have hundreds of miles of roads to inspect on a regular basis and patch holes in the road surface as resources permit. Potholes can be repaired to last for many years if the causes of the initial problem are corrected. Generally, repairs are done in an expeditious manner to maintain a safe roadway resulting in only a temporary pothole repair. The goal is to repair all reported potholes on County-maintained roads promptly. Priority is given to potholes that may affect drivers, the rest are on a first come, first served basis. The Division appreciates input from citizens giving the exact location of a pothole, with a specific address or intersection as it facilitates the work request process. Pavement patching work is typically performed at a unit price of approximately $71 per ton.

Intersection Safety Improvement Program (ISIP)

In July 2001 the Department began its implementation of an Intersection Safety Improvement Program which was supported through approval of the fiscal year 1999 capital budget. The program will systematically identify intersection improvements that will improve and more effectively handle vehicle-turning movements during emergency and routine responses. This may include the realignment of intersecting roads, the paving of shoulders in the fillet radii or reducing the roadside fore-slopes to 3:1 slope or flatter which can be accomplished under one of the pavement overlay contracts.

Clear Zones

The term "clear zone" is used to describe the relatively flat area immediately adjacent to the travel-way and shoulder that should be unobstructed. The recovery area should be clear of all unyielding objects such as trees, sign supports, utility poles, light poles and any other fixed objects that might severely damage an out-of-control vehicle. The width of the clear zone is influenced by the traffic volume, speed and embankment slopes as specified in the AASHTO Roadside Design Guide. For low speed rural collector roads, a minimum clear zone of ten (10) feet should be provided. For urban areas, a minimum clear zone of 1.5 feet should be provided behind the face of the curb. Those areas unable to meet these guidelines may require other forms of protection such as the installation of guardrail. As a general rule, utilities and landscaping should be located outside the clear zone near the right-of-way line.

Obstruction Removal Ordinance

In the Spring of 2002, the Board of Commissioners adopted a new Comprehensive Zoning Ordinance, which will permit the Department of Permits and Inspection to remedy and/or the DPW&T to legally encroach upon private property to remove identified roadway hazards. The purpose of the policy is to correct safety related concerns on negligent or non-responsive landowners.

Basketball Hoops

The County views portable basketball hoops as being similar to portable street-hockey nets, skateboard ramps, and other paraphernalia which are sometimes placed within the right-of-way in residential neighborhoods by the residents. The County responds to complaints and determines whether the encroachment on the public right-of-way constitutes a danger to public safety. We ascertain whether there exists a hazard to vehicle or pedestrian traffic, an obstruction to the free passage of school buses, mail deliveries, street sweeping or refuse collection equipment, an obstruction to sight distance, or constitutes an inconvenience to others. An example of an inconvenience to others would be where a portable hoop is placed so as to block another person's driveway or sidewalk path. If placement of the hoop is determined to be a hazard, the stand must be removed from the right-of-way.

If the basketball goal is not removed from the right-of-way within thirty (30) days of being notified by the County, it will be confiscated. If confiscated, the item will be retained at the County Highways maintenance facility for a period of thirty (30) days and may be claimed by the owner. At the end of this period, if not claimed by the property owner, who will be responsible for any costs incurred, the basketball hoop(s) will be discarded.

Storm Related Debris

Minor and major storm events often result in flooded conditions, fallen limbs or the deposition of other debris along the roadside. The debris must be removed from with in the travel-ways and adjoining areas to maintain the roads in a safe and passable condition. During unusually severe storms the Department also assists utility companies and the State Highway Administration in their efforts to restore power and re-open roads to through traffic. Storm debris is collected and brought to the St. Andrews Landfill Facility for disposal or processing into mulch.

The priority of treatment to accomplish roadside improvements are:

  1. Removing fixed objects and providing traversable terrain features
  2. Relocating fixed objects that cannot be removed
  3. Retrofitting fixed, non-movable objects with breakaway features
  4. Shielding potential hazards that cannot otherwise be improved
  5. Delineating objects when it is impractical to do anything else

Flood Prone Roadways

A flood prone roadway is defined as any public road that has a history of being covered by enough water in a manner that the road surface, markings, and edges are not visible to the operators of a motor vehicle, cyclists, or pedestrians. Such conditions could be caused by stream/river flooding, poor drainage along roadways, or normal surface runoff. Water on the roadway could be both standing and moving, and could also leave debris such as gravel, leaves, and sticks on the roadway. Duration of a flood event can vary from minutes to days.

Suddenly changing water depths, water currents, and road damage can make crossing a flooded roadway very dangerous for both motor vehicles and pedestrians. Six inches of swiftly moving water can knock people off their feet. Two feet of water can float most cars and strong currents can easily push vehicles into deeper water. It only takes a thin layer of water to cause a moving vehicle to hydroplane. Rural areas are particularly vulnerable because roads are lightly traveled and often not closed to traffic as quickly as urban roadways during storm events. To help warn users of public roadways, Flood Area signage and depth gauges (at low areas) are installed in areas that have been known to be historically prone to flooding.