District 4 Glossary of Transportation Terms
Glossary of Transportation Terms

(See also our Frequently Asked Questions page)

  • Agility Agreement: An agreement between local governments, municipalities, other public agencies, etc. and PennDOT for an exchange of services. A municipality performs work on a State highway, while the Department provides services of equivalent value for the municipality.
  • Business Plan and Budget : An outline of the District's accomplishments, goals and future plans. It is prepared annually for each District and each Central Office Bureau.
  • Bituminous Concrete: A paving material composed of a petroleum derivative and crushed stone or crushed gravel. Often called blacktop or (erroneously) Macadam.
  • District Wide Safety Index: A district measurement, which measures the overall safety program for a county or district office. It measures both reactive and proactive efforts being made toward a safety program.
  • ECMS: Engineering Construction Management System. A system by which design contracts are advertised and consultant firms are selected and contracts are administered. It is accessed through the Department's Web Site (Services & Software).
  • HAR: Highway Advisory Radio. Highway Advisory Radio is a system of low-power AM radio stations that broadcast information for motorists, such as traffic congestion and special event information. They usually broadcast below 540 KHz or above 1640 MHz.
  • ITS: Intelligent transportation system. A network of changeable message signs and highway advisory radio that notifies drivers of changing roadway and traffic conditions.
  • Letting Schedule: The schedule of projects to be advertised and bid by independent contractors.
  • Milling: Milling is the removal of a thin layer of bituminous concrete, or blacktop. This is done to remove an old, oxidized, layer of material, and to eliminate the build up of material which could conflict with curbs or bridge clearances.
  • PennDOT: The Pennsylvania Department of Transportation. Formed in 1970 from the Department of Highways, PennDOT incorporated Motor Vehicles (from the Dept. of Revenue), Rail Freight, and Aviation functions. The Department is a Cabinet-level agency under the Governor's jurisdiction.
  • Piggyback purchases: A process by which municipalities can purchase materials on our statewide contract.
  • Posted bridges: Bridges that are limited to a particular weight or to one truck of legal weight at one time.
  • Posted roads: A road restricting certain weight limits. For example, no trucks over 20,000 tons allowed on this road.
  • Resurfacing: The process of overlaying a road with new blacktop, or bituminous concrete. Often called an overlay. This new layer is usually 1.5" to 4" thick. Often resurfacing is preceeded with milling.
  • Superpave: A new technology of bituminous materials (black-top) being used to pave our roadways. The materials in the pavement are matched to climate of area where it's being used. The chief advantage of superpave is reduced rutting of the pavement by heavy trucks.
  • Turnback: A program through which a state highway owned by PennDOT is given back to the local municipality for to maintence. Before a highway is turned back to a municipality, the Department improves it to the appropriate standard.
  • VMS: Variable Message Sign. "Variable message sign" is PennDOT's name for those flashing electronic signs that you see along our interstates and expressways. The variable message signs are used to relate traffic information and safety messages to drivers. The electronic sign could be one of three types. One is the familiar mobile orange electronic sign along the side of the highway. Another type is a taller fixed position electric sign. The last type is what's called an overhead variable message sign. The overhead sign is larger and is mounted above the lanes of traffic. Like the electronic signs on the side of the highway, the overhead message sign can be programmed to provide updated travel messages to drivers.