Voluntary Emissions Reduction

Using input from the public, a new type of vehicle emissions information system has been developed which integrates an innovative variable message sign with an on-road vehicle emissions sensing system to display individual vehicle emissions information to passing drivers. The Smart Sign was successfully operated from May 1995 to August of 1996 in Denver Colorado as part of a Federal Highway Administration Intelligent Transportation System operational test. During that time more than 4 million readings were provided to more than 250,000 individuals at a cost of $0.02/test.

The original deployment was located in Denver at the intersection of Speer Blvd. and Interstate 25 (see site layout below). The system operated 7 days a week 24 hours a day in conditions that ranged in temperature from -20 to 100 degrees F. The more than 4 million readings were distributed as 86% 'Good', 10% 'Fair' and 4% 'Poor'.

After the Speer Blvd. exit was redesigned the sign received a new life at the intersection of 6th Ave. and Interstate 25. The sign operated for more than 10 years at this location and was finally decommissioned in 2014.

Using vehicle information the National Center for Vehicle Emissions Control and Safety conducted a follow-up phone survey which showed that 76% of the weighted population had a favorable impression of the sign. Sixteen percent of the poor's (1.6% of the overall fleet) reported to have already taken corrective action as a result of the Smart Sign.

The three faces of the Smart Sign. The sign is 11 ft. x 8 ft. and was constructed by Skyline Products, Inc. of Colorado Springs.

In addition to the sign a brochure (see below) and a hotline number were provided for additional information. The brochures were distributed at more than 50 Conoco stations in the Denver Metro area.

The Smart Sign system is capable of being converted to a portable system enabling it to be used in a number of new and innovative applications. The sign can be mounted onto a trailer along with a diesel generator which is used to power the system. The remote sensor is mounted above ground in weather protective housings upstream of the sign. The photographs below show the system in use at an on-ramp in the Denver area.


Evaluation Report for ITS for Voluntary Emission Reduction: An ITS Operational Test for Real-Time Vehicle Emissions Detection, L. Bohren and D.C. Williams Jr., The National Center for Vehicle Emissions Control and Safety, Fort Collins, 1997.

Clearing the Air, N.J. Lacey, L. Bohren and R.B. Hutton, ITS World, Sept/Oct. 42-44, 1997.

Final Technical Report for ITS for Voluntary Emission Reduction: An ITS Operational Test Using Real-Time Vehicle Emissions Detection, G.A. Bishop, D.H. Stedman and R.B. Hutton, Final Report to CDOT, May, 1998.

Drive-by Motor Vehicle Emissions: Immediate Feedback in Reducing Air Pollution, G.A. Bishop, D.H. Stedman, R.B. Hutton, L. Bohren and N. Lacey, Environ. Sci. Technol., 34:1110-1116, 2000.

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The Smart Sign was last updated Wednesday, June 15, 2016