PennDOT Maintenance Activities
Although PennDOT crews are common sights on Pennsylvania's 40,000 roadway miles and 25,000 bridges, many of our customers may not realize the scope of work we do. The Maintenance First series was developed to shed some light on the operations PennDOT performs year-round in our mission to provide an efficient transportation system. You can also see
how potholes are formed (PDF).
Surface Treatment |
Shoulder Cutting |
Shoulder Grading |
Pipe Replacement & Cleaning |
Mechanized Patching |
Manual Patching |
Joint & Crack Sealing |
Winter Operations |
Vegetation Management |
Line Painting |
Bridge Maintenance & Cleaning |
Commonly known as "oil and chip," this maintenance operation is used as a way to extend the life of low-traffic-volume roads for another three to five years.
This activity is performed when temps are greater than 60 degrees, generally in the months of April to October. Surface treatment requires a sweeper, oil distributor, a stone chipper, rollers, numerous dump trucks, and a crew comprised of approximately 18 crew members.
The operation begins with the roadway being swept clean of all debris. Then, oil is sprayed to the roadawy with a layer of fine stone immediately applied on top of the oil. It is then rolled in place with all loose agregate swept from the roadway once cured.
Generally, it takes about two days for the stones to fully bond in the hardened asphalt. Motorists should reduced their speed on their roads until the stone and the asphalt fully adhere.
This maintenance treatment seals the road surface to keep water out and restores the friction of the surface to enhance traction.
Shoulder cutting removes excess material and debris from unpaved shoulder areas. This improves drainage and allows water to leave the roadway.
This process requires equipment such as graders, trucks, brooms, belt loaders or wheel loaders, and rollers. Workers move in front to spot and mark or remove objects which could potentially damage equipment, such as sign posts, glass, and large rocks.
The grader follows the workers, cuts excess material from the shoulder and places it in a pile to be picked up by a loader. It is deposited into a truck to haul to a fill site. Sweeping to clean excess material remaining on the roadway is the next piece of the operation. Finally, the roller follows the loading operation to compact or stabilize the exposed soil.
This is an important highway maintenance operation. When drainage systems do not function properly, water collects on the roadway, creating potential icing conditions in the winter and weakening pavement, causing potholes.
Shoulder grading involves the shaping and stabilizing of unpaved roadway shoulder areas.
This maintenance operation is usually programed between April and November. A shoulder grading crew utilizes about 10 workers to operate graders, dump trucks, a roller, and power broom.
PennDOT grades shoulders to eliminate the drop-off between the roadway and the shoulder and to allow water to drain away from the road surface. If ruts are allowed to form and remain on the shoulder, water can enter and damage the edge of the pavement.
The outside edge of the shoulder is cut toward the road. The cut material is then regraded over the shoulder to fill in low areas and ruts. The material is then swept from the roadway and compacted with a roller.
Pipe Replacing & Cleaning
To maintain the effective flow of water around the state's roadways, pipe replacement and pipe cleaning are essential. Controlling water flow is one of the most important aspects of maintaining pavements. Uncontrolled water flow will damage both the pavement surface as well as the area under the pavement, causing deterioration.
Pipe replacement is a year-round activity. Typically, pipe is installed prior to repaving or sealing the pavement surface. A standard pipe crew consists of a foreman, three equipment operators and four additional crew members. Equipment includes a crew cab, backhoe, two dump trucks, a compressor and compactor. Because of its durability and ease of handling, most pipe replacements are plastic, with the remainder split between metal and concrete.
Pipe replacement operations consist of cutting or sawing pavements, creating a trench in the sub-pavement, installing the pipe, filling the trench, compacting the fill material and replacing the pavement surface.
Pipe cleaning is mostly performed in the summer months by flushing them with water. Most pipes are cleaned with a high-velocity sewer cleaner. To ensure that water reaches the pipe, additional assemblies are needed such as ditch cleaning, shoulder cutting and shoulder grading which keeps water flowing along its natural drainage course.
Mechanized patching is used to patch limited roadway areas that have extensive potholes, large areas of cracked pavement and depressions. It also improves the smoothness of the road surface.
This maintenance activity is usually completed during the summer but can be accomplished at other times of the year as road & weather conditions permit. The crew typically requires between 13 and 15 workers, several dump trucks, a paving machine, a roller and a tack-coat applicator.
Mechanized patching involves six specific steps — marking the area that needs patched, cleaning the area using a street cleaning broom, filling any large holes or low areas with patching material, compacting the material, applying a layer of asphalt over the marked area and compacting the area with a roller.
If workers did not perform mechanized patching, the damaged road surface would further deteriorate, forcing PennDOT to completely rebuild the road or perform other, more costly corrective measures.
Manual patching is most commonly known as pothole patching.
Most permanent pothole patching is completed in the spring when temperatures stay consistently above freezing. Weather permitting, crews patch potholes during the winter using a cold patch.
Cold patch is asphalt mixed with soap, water and fine stones. The soap and water allow the material to remain flexible so crews can work with it. The cold patch material is simply placed into the pothole with a shovel and then compacted. After the soap and water evaporate, the material will become hard. Although this is designed to be a temporary repair, cold patch jobs can last two or more years.
Hot mix is a permanent patch for a pothole which requires a mixture of pure asphalt and fine stone heated to about 300 degrees Fahrenheit. The pothole is cut square, cleaned and then treated with a tack-coat of asphalt that acts as a glue. After the tack-coat application, the hot mix is placed into the pothole and compacted using a roller or other device. If potholes were not repaired, the road surface would break up and require more expensive corrective measures.
Joint & Crack Sealing
Joint sealing is used to seal the joints on concrete roads while crack sealing is used to seal cracks on asphalt roads.
Crack sealing prevents water from seeping through cracks in an asphalt road, which can lead to potholes and pavement break up. Joint sealing prevents stones or other hard materials from being deposited between slabs on a concrete roadway. If a significant amount of material does get into the joints, the road cannot expand and contract with the changing temperatures and will ultimately break at the joints or the slab may buckle.
Crack sealing is typically performed from March through November depending on weather conditions. Joint sealing is typically completed April through June and September through November. This time frame is utilized because the joints are fully open. Both types of operations require about eight workers, a dump truck, a heating kettle for the sealant and a device to apply the sealant.
These maintenance activities involve removing debris from the crack or joint to be sealed and then applying a liquid asphalt material.
Winter Operations include the removal of snow and ice as well as applying deicing materials on all state highways and bridges. The heart of winter operations involve a skilled operator, and a dump truck equipped with a salt spreader, snow plow and often, a wing plow.
During severe winter storms, PennDOT also schedules at least one mechanic at each garage site to take care of any major equipment failures or breakdowns.
To prevent ice from building up on the road surface, PennDOT trucks spread a mixture of salt to melt the ice and small stones called anti-skid to provide traction. In some rural areas, PennDOT will limit salt and increase the amount of anti-skid spread over the road surface because salt depends on a certain amount of traffic to be fully effective.
During a storm, PennDOT will plow and salt major highways first before moving to the less traveled rural roads. During severe winter storms, equipment is often redirected from assigned rural routes to assist with plowing the more heavily traveled roads first.
Another weapon that PennDOT has in its winter arsenal is anti-icing. Anti-icing essentially involves treating the road with brine (salt water) before freezing precipitation starts to fall. The water part of the brine evaporates and the salt that remains helps prevent ice from forming a strong bond with the road surface.
PennDOT also has 62 facilities statewide capable of making their own brine. An average of more than 9 millions gallons of anti-icing material was used in the last five years. For more on PennDOT's winter operations, visit the
Winter section of our website.
Vegetation management beautifies the state's roadways, makes them safer, more accessible and enhances the scenery.
Mowing, pesticide spraying and selected tree thinning are the processes that make up the management program.
PennDOT mows approximately 112,000 acres annually from May through October. How often roads are mowed is determined by their traffic volume and posted speed limit as well as growth height.
In areas in which mowers cannot safely travel, herbicide is applied to the roadside vegetation. Herbicide use is more cost effective than tree cutting or trimming. Herbicides control the extensive root systems of invasive plants. All three activities maintain visibility on the roadsides.
A typical tree trimming crew consists of a foreman, equipment operator and four to five crew members. Tree thinning equipment includes a crew cab, dump truck, wood chipper, chain saws and other hand tools as required. For mowing, PennDOT uses 228 department-owned tractor mowers and contract mowers.
Vegetation management is emphasized during the growing season and extends through the winter, when snow removal isn't required.
Each year, PennDOT line painting crews apply more than 1.6 million gallons of yellow and white traffic line paint to highways to help guide motorists.
This amount of paint is approximately enough to fill 470 four-foot deep, 12-foot diameter, above ground swimming pools. PennDOT starts painting the traffic lines in early summer. By the time this operation is completed in October, PennDOT crews will have painted more than 114,000 miles of lines, enough to circle the globe nearly five times.
PennDOT paints primarily road and highway dividing lines, but also paints some timing bars for state police, STOP road markers and some railroad crossing marks.
The weather must be warm and dry for painting because rain, high humidity or temperatures below 50 degrees Fahrenheit will increase the normal drying time of between 90 and 120 seconds.
The PennDOT line painting crews' equipment heats the paint to about 110 degrees Fahrenheit and then sprays the material on the road. While the paint is still wet, beads made of recycled glass are automatically applied to provide reflectivity.
PennDOT estimates that it uses approximately 11 million pounds of glass beads for line painting each year.
Bridge Maintenance & Cleaning
Pennsylvania has some of the oldest bridges in the country, with their average age over 50 years. Preventive maintenance is extremely important in extending the life of structures throughout Pennsylvania as well as the nation.
Poor structure condition is one of the nation's most pressing transportation issues. A good preventive maintenance program can enhance a bridge's life cycle.
PennDOT inspects most state bridges at least once every two years. Based on inspection results or structural needs, PennDOT crews do bridge replacements or structural repairs to steel or concrete components. Some PennDOT districts cast and build their own beams in the winter so they can use them for building in the summer.
Bridge cleaning is an important element of the state's Bridge Preventive Maintenance Program. The deck and substructure must be kept clean, with the drainage systems free of debris. PennDOT mandates that most bridges be cleaned annually.
PennDOT cleans over 16,000 bridges each year.
A basic bridge cleaning crew is comprised of a foreman, equipment operator and four crew members. Required equipment includes a crew cab, dump truck, sweeper and flusher.
The most important way in which roadway safety and information is relayed to our customers is through roadway signs.
Most PennDOT county operations have a single sign crew — a sign foreman and assistant — that install signs along state roads; a few larger county operations have additional crews. PennDOT is responsible for reviewing installed signs and determining if, because of age, vandalism, damage or other reasons, a sign needs to be replaced. Work is identified, signs are produced at the state's sign shop and, once completed, signs are scheduled for installation.
There are approximately 1.3 million state-owned signs in Pennsylvania. PennDOT's Sign Shop produces around 85,000 signs each year. Signs are made using aluminum sign blanks which are covered with high intensity retroreflective sheeting. After the sheeting is applied, either silk-screened or cut-out characters are applied for the sign's message.
The vast majority — 95 percent — of sign orders are filled within 14 days of receiving the order.