LCDOT is responsible for a system of approximately 300 centerline miles (874 lane miles) of arterial highways and more than 60 miles of bike facilities. Maintaining and preserving our current system takes top priority when putting together our annual improvement plan. Pavement conditions are easily noticeable to the traveling public and our pavement management program helps us evaluate when and where repairs are needed, and what level of repair is most appropriate.
There are numerous ways in which we inspect and test our pavements, and this helps us generate a set of recommended projects for the next five years, given budget availability. Spending tax dollars responsibly to perform preservation improvements at the right time saves dollars down the road.
Here is a brief explanation of the pavement management techniques we apply to preserve our system.
- Pothole filling & other reactive responses – These are quick repairs to take care of any issues that show up in between more extensive preservation measures. For example, a maintenance worker might fill a pothole as he/she drives by on the daily routes. These are meant to be “band-aid” type fixes to provide temporary relief.
- Crack sealing - LCDOT performs crack sealing on pavements that are about 3 years old to address working cracks and paving seams. Crack sealing prevents moisture from getting into the pavement structure, which could lead to deterioration.
- Surface patch – The Maintenance Department identifies roads with a high level of cracking and other distresses at the end of the winter season. They also highlight areas that create issues for our plows with a lot of bumps or dips. In between May and July each year, the distresses are repaired by grinding down and replacing the top 2” with new asphalt.
- Full depth patch – This is an annual LCDOT program that addresses areas on concrete or asphalt pavement where significant deterioration has occurred. Sometimes pavement distress is so bad in the lower layers of pavement or the base of the road that a full depth patch is needed. However, it is more cost effective to perform surface patches, as it helps prevent more substantial full depth repairs down the road.
- Pavement Rejuvenator - LCDOT implemented a new preventative maintenance program that applies maltene-based pavement rejuvenator to asphalt roadways with recently completed surfaces, extending the life of the pavement by about five years. The rejuvenator inserts maltenes, or glue, allowing for a tighter aggregate surface. This leads to less rocks chipping off, slows the oxidation process, and prevents water from sitting in cracks in the pavement, reducing damage from freeze-thaw cycles.
- Microsurfacing – Microsurfacing is a technique used to extend the life of a road for a fraction of the cost of a resurfacing, but it does not repair the road. A thin treatment is applied to the surface of the road to seal it in and protect the pavement from the elements, improve surface friction, and slow down the aging process, but some cracks and bumps will still come through. We expect to get an additional 5-8 years (on average/varies by location) out of the pavement before we need to do another treatment or resurfacing. In the meantime, the money that we save on a microsurfacing project at one location is spent on a road that is further deteriorated and needs resurfacing right away in another location.
- Resurfacing – Resurfacing a road is the most extensive preservation technique and it lasts the longest (15 years on average). For a resurfacing, various design elements are considered to bring the road up to standard, some of which may require full topographic survey. For example, a resurfacing may require regrading ditches for optimum drainage, and where possible, extending the width of the road to add bike-friendly shoulders. To resurface a road, the pavement is ground down, and new asphalt is added. Up to 40% of the asphalt grindings can be recycled into the mix for the new pavement for a road, bike path, or used in the base layer for a brand new road.
Full depth patching on Buffalo Grove Road
Hunt Club Road resurfacing
How do we choose which roads to repair?
Pavements age at different rates based on a variety of factors like traffic, weather, and the soil beneath the pavement. For this reason, some roads need to be repaired more frequently than others. Each fall, one-quarter of the pavement is tested on a four-year rotation and the test results are evaluated to produce an overall numerical rating (shown on the map, left). This data helps us determine what strategy to apply to which road and at what time. It might seem strange, but there are times when it makes better economic sense to take a “do nothing” approach now and perform a more comprehensive repair later.
Why are you repairing a road that was recently constructed?
Preventive maintenance items like crack sealing and microsurfacing seal and protect the pavement. When applied early in a pavement’s life, studies indicate that these preventive maintenance techniques will extend its life and reduce life-cycle costs. The chart to the right shows that preventive maintenance techniques applied at the right time can add more than 12 years to a pavement’s useful life at about 20% of the cost.