The state DOTs and FHWA have been working together to coordinate an orderly transition to the SI system.
As illustrated by the accompanying table and map, many state DOTs stayed with their original conversion target dates and are well along in their transition to SI.
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.
FHWA and AASHTO are currently reviewing the implications of this change.
States reported that metric conversion has cost about million over the five years from 1992 to 1997.
During this same period, authorizations for the federal-aid construction program amounted to 8 billion.
These estimates are a substantial increase from 1997 when projects using metric measurements made up 45 percent of the program. In this act, Congress mandated that federal government agencies use the SI metric system of measurements in their daily business to encourage U. industry to adopt SI and to become more competitive in the worldwide market.
Although we do not export our highways, we can and do export the technology to build them efficiently.
Some federal agencies have issued functional equivalences for their regulations; but other agencies continue to use inch-pound units in their regulations, accepting metric units in permit applications and the like; and still others use and require inch-pound units only in their documents.
Small- to medium-sized contractors remain concerned about the cost of converting their operations to metric units.
Currently, FHWA is funding a case study of metric highway construction projects to look at contractor conversion costs and to identify problems, solutions, and best practices.
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.