The City of Austin resurfaces all residential streets and most boulevards using a seal coat. To see recent seal coat applications, you may wish to drive through Shenandoah, Block House Creek or Brushy Creek North subdivisions.
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Proper preventative maintenance, like seal coating, can help ensure that the existing pavement structure will last for many decades. Asphalt streets consist of a 1 1/2 to 2 inch layer of asphaltic concrete most people just call asphalt or pavement. Over time, the asphalt ages, weathers, and oxidizes. It becomes brittle and cracks. While the old surface appears smooth, it contains hairline cracks that, if not treated, would continue to widen, deepen and eventually form potholes.
On most streets the work will only take about 30 minutes per block per lane. There might be a short period of time when the roadway in front of a residence is in an active work zone and, for safety reasons, the driveway is inaccessible. The first sweeping does not take place for 24 to 48 hours, so drivers should drive slowly. The surface is still “tender” for the remainder of the curing process. Tight turns, quick accelerations, or sudden stops and heavy braking may leave permanent marks in the surface in the first few months, especially on very hot days.
Tandem axle, double tire, garbage trucks make sharp turns in cul-de-sac bubbles and cut into a fresh seal coat thereby peeling up large sections of the surface. This is especially true in hotter weather. We will come back later with a different process to treat those areas. This other process is called a fog seal. Fog seals work better with the heavy, slow-speed turns at the end of the street.
We do not tow vehicles for the seal coat operation. If residents are unable to assist us by moving vehicles off the street, the sweepers will be unable to vacuum the rock from under them. Loose gravel also tends to accumulate at low spots, on the outside of curves and at intersections; however, all of this typically amounts to less than a gallon of gravel per block, and we would be glad to clean up remaining rock. If concerned residents will contact the resurfacing hotline, we will come back to sweep up any excess rock 512-943-3393 within 24 to 48 hours.
We ask that each resident help maintain the quality of their street by moving vehicles parked on the street in advance of the seal coat work. In the cases where residents have not moved their vehicles, seal coat production will be reduced and we will be back with a hand crew to cover those spaces at a later date. This will be more expensive and result in fewer streets that can be seal coated that year.
The surface will smooth out with traffic over the first four to six weeks as the material cures and the gravel particles interlock and embed into a tighter surface. While this process is slow, it is happening. The street will look completely different in eight to twelve weeks with a darker, tighter, smoother surface. It will never be as smooth as the old surface; however, it will provide good wet weather traction, preserve the remaining life of the street, and seal most of the cracks.
It is best to wait at least 30 minutes after rock has been down before walking on the new pavement surface. Remember that the curing process takes longer than 30 minutes so, if you choose to walk outside, be sure to remove shoes before going back in your house and make sure that all pets’ feet are clean before going back in, as well.
Seal Coat Maintenance is often performed on an 8 - 10 year basis. If preventive maintenance, crack sealing and seal coat resurfacing, e.g., is conducted on Williamson County roads and streets on a routine basis, the existing pavement structure will last for many decades.
Two different seal coats of varying ages: on the left is a seal coat approximately a couple of months old, while the one on the right is approximately four years old.
What the residents are used to driving on is a pavement structure that has a hot mix asphalt pavement (HMAC) surface with a flexible crushed rock base below it. The cost to resurface an existing road using a standard HMACP overlay is 5 to 6 times more expensive than resurfacing a road with a seal coat. Should the roads not be resurfaced at all, they will continue to degrade and there comes a point when resurfacing maintenance is no longer effective and the road would need to be rebuilt. The cost to rebuild a road is 10 to 15 times greater than the cost of seal coating.
Yes and No. Yes, this is the product that is being utilized to resurface all subdivision roads in the unincorporated areas of Williamson County. As expressed earlier in the FAQs, it is much more cost effective to resurface with a seal coat than with HMAC, due the County's budget constraints. No, what you see on your street the day of resurfacing is not how it will look in the future. We spread more rock than is necessary to decrease the likelihood that residents would get asphalt on their vehicles and feet. That excess rock will be vacuumed up (it might take a couple of trips down your street) and the remaining rock (that which adhered to the asphalt) will continue to work itself into a tighter structure with continued driving upon it. The rock will also tend to darken over time.
You may call our Resurfacing Hotline, 512-943-3393, to hear daily updates of roads on which our crews are currently working or you may visit our County Roads page.