streets

​Paving & Surface Treatments

The Infrastructure Department provides repair services for Thornton streets. Such repairs may include potholes, crack sealing, street failures, and unimproved road grading.

Street Rehabilitation Program

The project includes rehabilitation of city streets as determined by the Pavement Management System and staff recommendations.  Rehabilitation includes asphalt overlays, crack seal, hot chip seals, street concrete replacement (curb, gutter, cross-pans), and accessible ramp replacement as required.  Both city crews and contractors participate in the Street Rehabilitation treatments and locations. Project locations are shown on the map below.

 2019 Street Paving and Surface Treatment.pdf

2019 Street Paving and Surface Treatment schedule.pdf

Concrete Replacement Program  

 City Council has approved a $140,000 a year budget for the purposes of replacing broken or damaged concrete within the city.  Locations are determined by the severity of damage as they relate to pedestrian hazards, structural damage, surface deterioration, and impact to drainage. Work generally begins in March, weather dependent, and can last several months. 

Crack Seal

Cracks can form in asphalt pavement through various modes of distress. Regardless of how the cracks form, they must be repaired to help protect the pavement structure. If the cracks are not maintained, they can ravel and increase in size. Unsealed cracks allow water to penetrate into the structure from the pavement surface, which eventually causes potholes and further deterioration. Water infiltration is the number one enemy of pavement. Crack sealing is the most important and cost effective maintenance option to help protect integrity of the pavement.

Benefits of Crack Seal:

  • Prevents water from entering the pavement and sub base

  • Prevents debris from entering the crack

  • Prevents or delays pothole formation

Life expectancy of Crack Seal is approximately 3-5 years.

 

Hot-In-Place Recycling

Hot-In-Place (HIP) recycling is a single pass repaving process using specially designed equipment in a simultaneous, multi-step process that removes some of the existing asphalt, reheats and recycles it with a rejuvenating agent and then is placed on the road surface with additional new Hot Mix Asphalt placed on top of it.  This process provides a smooth restored riding surface.

Benefits of Hot-In-Place Recycling:

  • Improves the smoothness, durability, and appearance of the street with like-new results

  • Minimizes traffic delays because of its single pass process

  • Environmentally friendly by reusing existing asphalt

HIP recycling has a life expectancy of approximately 8-10 years.

Hot In-Place Recycling: Is one option used instead of a typical Mill and Overlay operation.  The city of Thornton uses this process on all asphalt street types (Arterial, Residential).  A benefit of using this process on residential roads is the minimal impact to residents.  The HIP is a shorter paving process, and allows residents back on their street in a timely manner.

Hot Chip Overlay

Hot Chip Overlay is a two-step surface treatment that combines a Chip Seal and a thin overlay of open graded friction course (Hot Chip Seal) providing a double application of material.  This provides a waterproof membrane and the Hot Chip Seal provides strong wearing surface that will improve the profile of the existing asphalt.

Benefits of Hot Applied Chip Overlay:

  • Improves skid-resistance and safety with a high friction surface

  • Provides asphalt pavement additional structural strength

  • Quiet surface treatment especially on high volume traffic roads

  • Enhances the appearance of the road by improving the surface texture, profile and surface color

Hot Chip Overlay has a life expectancy of approximately 8-10 years.

Since the Hot Chip Overlay is a two-step process, it will leave the road bumpy at points during it construction, and slowing down is the best thing drivers can do until the final overlay is applied in the second step of the process. During the Chip Seal process, drivers may encounter loose rock, and should give extra distance to the car in front to avoid being struck by the loose material.

Asphalt Rejuvenator

Asphalt Rejuvenator is a liquid product that is sprayed on the road, and rehydrates the asphalt binder (black stuff) that holds in the aggregate.  By rehydrating the asphalt, binding the roadway will lose fewer aggregate and will result fewer potholes.  Rejuvenators can be thought of having the same results as lotion for skin.

Benefits of Rejuvenators:

  • Cost effective preventative maintenance treatment

  • Holds the aggregate in the roadway

  • Tightens and closes hairline cracks in the asphalt

  • Reduces potholes and large cracks

Asphalt Rejuvenator has a life expectancy of 5-7 years

Asphalt Rejuvenators are typically applied to Residential streets, and have a quick application time minimizing impact to residents.

Asphalt Mill/Pave

An asphalt mill/pave operation is the application where the top layer of asphalt is removed and replaced with new Hot Mix Asphalt (HMA). HMA is mixed, placed and compacted at elevated temperatures, hence the name. HMA is a combination of approximately 95% stone, sand, or gravel bound together by asphalt cement, a product of crude oil.  Asphalt cement acts as the glue to hold the pavement together.  The resulting Hot Mix Asphalt is loaded into trucks for transport to the paving site. The trucks dump the Hot Mix Asphalt into hoppers located at the front of paving machines. The asphalt is placed, and then compacted using a heavy roller, which is driven over the asphalt. Traffic is generally permitted on the pavement as soon as the pavement has cooled. 

Asphalt is America's most recycled material. The city of Thornton's HMA contains approximately 20% recycled asphalt.  Recycling is just one reason that asphalt is such a sustainable pavement.

Benefits of Hot Mix Asphalt Mill/Pave:

  • Less expensive than complete removal and replacement

  • Removes surface damage to street

  • Can improve drainage in streets

  • Re-establishes proper grade

  • Improves surface for smoother driving and better traction

HMA has a life expectancy of approximately 10-15 years depending on the volume of traffic.

Asphalt Base Patching with Geogrids

The city of Thornton utilizes a base patching with Geogrid textiles in its Street Rehabilitation Program to reduce the amount of deep cracking in asphalt pavement.  This process includes milling (removing) and additional 3+" of asphalt and placing a Geogrid textile mesh over the deep crack, the area is then backfilled with new Hot Mix Asphalt and a wearing course (see above) is then applied over the entire street.

Benefits of Asphalt Base Patching with Geogrids:

  • Greatly reduces the amount of reoccurring cracks

  • Stabilizes the bottom layer of the roadway

  • Provides a longer life for the wearing surface course

Asphalt Base Patching with Geogrids combined with a surface wearing course has a life expectancy of approximately 7-10 years depending on the volume of traffic.