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Delaware, Ohio 43015

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  Design Department 

PAVEMENT MAINTENANCE AND RESURFACING 


General:

With about 330 miles of county maintained roads and 520 miles of township roads in Delaware County, keeping pavement in good condition is a formidable task.  Each year, the county spends between $2 and $3 million on pavement resurfacing and maintenance activities to maintain smooth driving surfaces for motorists.  Restoring pavement markings is also included in the work of maintaining county and township roadways.

 

Pavement Condition - Important to Safety:

Good pavements are not only important for driver comfort, they are also a major element in roadway safety.  Good pavement resists rutting, potholes and skidding, which can contribute to accidents and damage to vehicles. 

 

Swerving to avoid a pothole is an unnecessary distraction for motorists that must already be alert for objects within the roadway.  Rutted pavement can cause accidents by pulling a driver out of their driving lane.  Pavements with good skid resistance can decrease emergency braking distance, which may be the difference between a near miss and a bad collision.

 

Road Condition Rating System:

The Design Department regularly inspects each mile of roadway in the county for pavement distress and damage, and updates the condition of the pavement and berms in the department's road rating system.  This road rating system is analyzed each year to determine which roads require substantial maintenance, and what the best type of improvement for the road is.

 

Annual Road Improvement Contract:

Each spring, the Delaware County Engineer's Design Department prepares plans, specifications and estimates for resurfacing, re-striping, crack sealing and other pavement maintenance activities. 

 

The roads selected for maintenance projects are determined largely upon their condition rating from the road rating system.  The annual Road Improvement Program includes asphalt resurfacing, microsurfacing, crack sealing, chip sealing, spot pavement repairs and berming.  Out of all these activities, asphalt paving is typically the largest budgetary item.

 

Asphalt Pavement:

As asphalt (blacktop) pavement ages, it is subjected to severe wear due to normal use by cars and trucks, as well as damage due to road de-icing chemicals and oxidation caused by ultraviolet light from the sun.  Over several years, asphalt pavement develops the familiar gray color because of the interaction of light with the oil based mixture that forms asphalt concrete.  Other environmental factors such such as rain and snow coupled with freezing and thawing are very hard on pavement and shorten the life span of all pavements.  Heavy truck traffic, coupled with poorly drained road subgrades can cause rutting and potholes.

 

Some of the new technologies and construction methods used in asphalt resurfacing that help to resist normal wear are as follows:

  • Performance Graded Asphalt Binder (PG):  Performance graded asphalt binder is the liquid tar-like substance in "blacktop" pavement that binds the stone aggregate mixture and allows pavement to be flexible.  Years ago, the liquid binder was not engineered in the same way that it is today.  Modern asphalt mixtures are designed to resist rutting in high temperatures when the asphalt binder is soft and also resist low temperature cracking by adding other chemicals and polymers to the binder to help it perform better under all conditions.

  • Fiberglass grid reinforcement fabric:  Fiberglass reinforcement is a relatively new technology that helps one of the common problems with asphalt pavement overlaid on Portland cement concrete (PCC) bases - reflective cracking.  Portland cement concrete and asphalt concrete expand and contract at different rates with changes in temperature, so asphalt surface course overlays frequently crack over top of joints in the underlying concrete.  These cracks admit water, salt and debris that further damage the pavement.  Fiberglass reinforcement fabric is laid over the joints in existing pavement or concrete base courses before the asphalt overlay.  The fabric helps to "bridge" the two layers and controls reflective cracking, thereby increasing durability and ride quality.

Portland Cement Concrete (PCC) Pavement:

Asphalt concrete (blacktop) differs from Portland cement concrete (regular "white" concrete) in that asphalt is a flexible mixture that can expand, contract, and flex up and down in response to load and temperature changes.  Portland cement concrete is a rigid mixture that maintains its durability through its strength and resistance to deflection (flexing) under load by a stronger interaction between the cement paste and the stone aggregate.  PCC is more expensive to construct initially than asphalt pavement, but its longer service live in some locations allows it to have a lower life cycle cost than comparable asphalt pavement.  Generally, PCC is better suited for high traffic intersections where cars and trucks brake and accelerate.  The horizontal forces generated by vehicles is better resisted by the rigid Portland cement concrete pavements than flexible asphalt pavements.  Many new construction projects use PCC at critical locations, such as freeway on/off ramps and high truck traffic intersections.

 

 


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