Because highway construction methods remain the same, most of the construction problems being encountered are related to materials.
These problems are not major obstacles, and they are being addressed on a case-by-case basis.
Therefore, converting the highway industry to the SI system will enable its many consultants, contractors, materials suppliers, and equipment manufacturers to compete more readily in the global marketplace.
[image-62]Public Law 94-168, §2 requires use of the International System of Units for measurement in U. Government programs, "except where impractical." That requirement is reflected in NASA policy, NPD 7120.4. The Metric Program Office at the National Institute for Standards and Technology (NIST) serves as the official coordinator for SI transition programs across the Federal government.
That measurement system, formally known as the "SI" system," after its name in French, , is almost universally used by all countries except the United States. is increasing, aerospace is recognized as one area where adoption will be difficult, due to the long-standing use of the U. Nevertheless, space programs do make significant use of SI, particularly for science measurement, and increasingly for hardware and operations, particularly as international cooperation in space increases.
Many local agencies rely on the state DOT's standard plans and specifications in developing their own projects.
These agencies will be forced to either use metric units, develop their own design aids, or use outdated standards when the state stops maintaining inch-pound standard plans and specifications.
Operating in a dual-unit environment is inefficient and increases the probability of error because people constantly translate between measurement systems.
Therefore, several state DOTs have converted their entire organization to the metric system of measurements.The effect on local highway agencies will vary from state to state.Some states set metric deadlines for their local agencies, but most states only encourage their local agencies to submit local projects in metric units.In carrying out the plan, the state DOTs, AASHTO, and FHWA have sought to accommodate the general public because there is no national mandate for the general public or industry to convert.Therefore, documents written for individual citizens (right-of-way documents) or available for public review (environmental documents, permit applications) are prepared in dual units unless a state DOT made the decision to use only metric units.The Federal Highway Administration (FHWA) Metric Conversion Plan was approved on Oct. The original plan required the state DOTs to convert by Sept. The National Highway System (NHS) Designation Act of 1995 revised the date to Oct. In the Transportation Equity Act for the 21st Century (TEA-21), which became law in June 1998, Congress removed the deadline entirely, making metric conversion optional for state DOTs.