Paint might not be the first word that comes to mind with the Portland Bureau of Transportation (PBOT), yet its streets have enough pavement markings to reach to Omaha, Nebraska. The City’s markings include 4,696 crosswalks, 99 pass-miles* of traffic lane lines, 734 pass-miles of center lines, 2,812 stop bars, 20,018 symbols and words, plus 180 miles of bike lanes.
Portland has over 1,600 miles of pavement markings. PBOT’s goal is to stripe 100% of the painted lines twice annually and maintain the thermoplastic lines as needed. This helps make sure all the City’s striping will be functional throughout the year.
PBOT uses two types of materials for its pavement markings: paint and thermoplastic. The per-mile material cost for thermoplastic is about 7½ times the per-mile cost of paint. Paint is quicker to apply while thermoplastic is generally more durable. Paint markings last generally sixth months to a year while thermoplastic can last up to 4½ years (depending on a number of factors including location, traffic volume and type, and pavement condition).
Given that the scope of resources needed to maintain transportation infrastructure greatly exceeds existing resources, PBOT looks for ways to do more with less. Observing that thermoplastic’s durability drops significantly when used on older roads, in 2012 PBOT’s Maintenance Operations group focused its use of thermoplastic on new roads, high wear locations (such as arterials with sharp curves) and designated Streets of Citywide Significance (SCS).
SCS are travel corridors PBOT prioritizes for expenditures due to their high traffic volume across all modes (freight, transit, motor vehicles, pedestrians and bicycles). Safety is a key element that factors into the SCS designation. The SCS designation includes PBOT’s designated High Crash Corridors.
This prioritization resulted in PBOT using less thermoplastic in 2012 and maintaining more lines with paint. As a result of the change in the business practice, productivity (defined as pass-miles striped per crew day) increased 70% from two years ago.
For more information, see PBOT’s 2012 Asset Status and Condition Report.
*A pass-mile is a continuous 4-inch wide line, one mile in length.