Chip-sealing — spraying an asphalt emulsion over existing pavement and then covering it with fine aggregate — is a cost-effective alternative to resurfacing asphalt pavements. Traditionally, however, it has only been used on rural and low-volume urban roadways.
During a recent visit to MnROAD, we filmed a road crew chip-sealing a test section on I-94 and spoke with MnDOT Research Project Supervisor Tom Wood, who explained why chip sealing can also be an effective treatment for high-volume roadways.
*Note: This story was updated on 08/12/2014 to clarify that the chip sealing shown in the video involves spraying an “asphalt emulsion” rather than “hot liquid asphalt,” as stated in an earlier version of this post.
Crossroads 
Chip sealing may help the longevity of the pavement but for many days it becomes completely unusable for anyone using a bike or wheelchair, and causes cars to spray dust everywhere. What can be done to mitigate these dangers?
Thanks for your question, Jeremy. I relayed your question to a couple of experts here at MnDOT. The short answer is, what you’re describing is a poorly done chip seal. A good chip seal requires sweeping the roadway clean on the day the chip seal is built, re-sweeping by the following morning and (optionally) fog-sealing to lock down any marginal embedded chips. MnDOT has a specification (2356) that contractors are supposed to follow when applying chip seals. Here’s a link: http://www.dot.state.mn.us/materials/bituminousdocs/Specifications/2014%20Spec%20Book/2356%20BITUMINOUS%20SEAL%20COAT.pdf
Let me know if you have any more questions. Thanks again!
You just did this on parts of the northbound lane of Hwy 53 north of Hwy 33. The road has lots of crossways cracks and it still rides as bad as it did before sealing. Other than tire noise, I can’t feel the difference where it has and hasn’t been done. The northbound lane of Hy 169 between Buhl and Virginia where chip sealing was done a couple years ago is much the same.
Why can’t the cracks be filled first so the chip seal actually has a chance to level things out? Why do these cracks form anyway? They don’t seem to be as bad in Wisconsin, the Michigan UP, or North Dakota. Do they do something different.