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MaineDOT Glossary

Highway Corridor Priority Measures

Priority Definition
Priority 1 Roads These roads include the Maine Turnpike, the interstate system and key principal arterials like Route 1 in Aroostook County, the Airline (Route 9), Route 2 west of Newport, and Route 302. The 1,400 miles of Priority 1 roads represent only 7 percent of the miles, but carry fully 40 percent of all vehicle miles traveled in Maine.
Priority 2 Roads These roads total about 940 miles. They are non-interstate, high value arterials that represent about 4 percent of the total miles of road but carry 11 percent of overall traffic.
Priority 3 Roads These roads generally are the remaining arterials and most significant major collector highways. These 2,050 miles represent only 9 percent of miles, but carry 19 percent of the traffic.
Priority 4 Roads These roads generally are the remainder of the major collector highways, often also part of Maine's unique state aid system, in which road responsibilities are shared between the state and municipalities. These 1,900 miles represent about 8 percent of total miles, and carry 10 percent of the traffic.
Priority 5 Roads These roads are 2,500 miles of minor collector highways, almost all on the state aid system. They represent 11 percent of miles, but carry only 7 percent of traffic.
Priority 6 Roads These roads are local roads and streets, and are the year-round responsibility of our municipal partners. Though they carry just 13 percent of the statewide traffic, these 14,300 miles make up 61 percent of the total miles.

Customer Service Levels

Customer Service Level Category Definition
Crash History Saftey This measure includes the two types of motor vehicle crashes most likely related to the highway- head-on and run-offroad crashes. The A-F scale compares these crash rates with the statewide average.
Paved Roadway Width Saftey This measure compares total paved width (lane plus shoulder) with minimum acceptable widths by Highway Corridor Priority (not new design standards). If a highway segment fails this minimum, the Safety Customer Service Levels for that segment is decreased one letter grade.
Pavement Rutting Safety This measure looks at wheelpath rutting, since excessive rutting holds water and contributes to hydroplaning and icing in winter. The A-F scale set points vary by Highway Corridor Priority, and are based on hydroplane tests.
Bridge Reliability Safety This measure is pass/fail. If a highway segment contains a bridge with a Condition Rating of 3 or less (excluding non-overpass decks), the Safety Customer Service Level is decreased one letter grade. These bridges are safe, but may require increased inspection or remedial work that could affect traffic flow.
Pavement Condition Condition This measure uses the Pavement Condition Rating (PCR), a 0-5 scale that is composed of International Roughness Index, rutting, and two basic types of cracking. The A-F scale varies by Highway Corridor Priority.
Roadway Strength Condition This measure uses the results of the falling weight deflectometer, a device that estimates roadway strength. The A-F scale is uniform across Highway Corridor Priority, since even low-priority roads must support heavy loads in Maine's natural resource-based economy.
Bridge Condition Condition This measure converts the 0-9 national bridge inventory (NBI) condition ratings to pass or fail; it is uniform across Highway Corridor Priority.
Ride Quality Condition This measure uses the International Roughness Index (IRI), which is expressed in inches per mile of deviation. IRI is the nationally accepted standard for passenger comfort, and the A-F scale varies by Highway Corridor Priority.
Posted Road Service Each year, MaineDOT posts more than 2,000 miles of road during spring thaw to protect their longevity, but some posted roads directly affect Maine's economy. Road segments that are permanently posted get a D, those with seasonal postings get a C.
Posted Bridge Service This measure uses load weight restrictions to arrive at an A-F score that varies by Highway Corridor Priority.
Congestion Service This measure uses the ratio of peak traffic flows to highway capacity to arrive at an A-F score for travel delay. Peak summer months are specifically considered to capture impacts to Maine's tourism industry. This scale is uniform across Highway Corridor Priority, since tourist travel is system-wide and sitting in traffic affects customer service similarly on all roads.

Project Status

Project Status Definition
Awaiting Kick-off Projects with construction funding that have a kick-off date forecasted.
Design/Permitting Phase Projects with construction funding that have been kicked-off and forecasted for construction to begin.
Construction Phase Projects with construction funding where construction has begun.
Construction Complete Projects with construction funding where the construction phase is complete.