The random temperature cracking opens more as the pavement ages. The cracks do not close, because the pavement contracts horizontally when it cools, but expands vertically when it warms up. However, there is small expansion horizontally. Because the asphalt cement has inherent healing properties studies have shown that closely spaced joints can remain resistant to water penetration.  
One method to build joints in the pavement is a patented process that cuts temporary grooves in the hot pavement behind the paver but before the first roller.

The staff at B. R. Amon & Sons, Inc. have developed and patented this process of building joints in asphalt, providing a longer lasting mechanical means to resist climate damages to the pavement. To date almost all efforts in asphalt pavement design have relied on chemistry of the asphaltic binder to achieve improvements in pavement design. At best the chemical approach is only a temporary solution. This process is available to our customers. We can provide cost estimates for applying it to your project. If there are further questions, we will gladly discuss your project requirements.