By Mark D. Blow, P.E.
Customer surveys show one undeniable fact; motorists do not like construction zones.
Congestion on unimpeded roadways is bad enough without having to deal with orange barrels and cones. Many pavement engineers striving to minimize the disruption are choosing asphalt. The mantra of “Get In, Get Out, Stay Out” is elevated in importance, as increasing traffic levels outpace capacity improvements.
Get in – get out
Proper planning, advance notice and communication to commuters are essential when “Getting In” to a project. The “Get Out” phase is greatly enhanced by the placement of asphalt.
With the ability to mobilize a manufacturing plant and materials to the job site, extremely high productivity can be achieved. Production rates can easily exceed 5,000 tons per day. That reduces a major 150,000-ton project to 30 paving days or less. Depending on the type of project being constructed, driving lanes can be striped and opened to traffic within hours of final paving with no curing periods to obtain design strength.
Multiple-lane facilities with high traffic volumes are often reconstructed one lane at a time and it is not uncommon for those projects to span multiple construction seasons. The high production rates associated with asphalt paving allow the total corridor to be placed in a matter of months instead of years.
The speed of construction can also be accelerated on urban arterial and collector routes. Thicker sections of long-life asphalt pavement, also termed perpetual pavements, provide the opportunity to construct a smooth, quiet and safe roadway that will last well beyond traditional life cycle cost periods.
The proper selection of Performance Graded (PG) asphalt binders has been documented to virtually eliminate thermal cracking on newly constructed asphalt roadways. By using high quality design and construction practices, these routes can last 20+ years before a scheduled mill and overlay will need to be performed. This planned and scheduled renewal of the roadway provides the traveling public with the greatest lifetime smoothness and drivability that can be achieved.
Speaking of future rehabilitation, the use of milling machines that also profile the surface, allows asphalt pavement to be “milled and filled” in unparalleled time. Disruption to local business is minimized as the pavement is quickly restored to its original condition. In fact, it is now common to mill and fill high volume congested routes at night with no disruption to rush hour traffic.
Check out YouTube video for the “6-Hour Shift” by Marshall Klinefelter and see how asphalt pavement is essential in keeping 274,000 vehicles per day on the move.
What can be better than driving home from work on an old road and going back to work the next morning on a new road? There is no better way to “Stay Out” than that!
Blow is an Asphalt Institute Senior Regional Engineer based in South Dakota.