In Nebraska, a portable speed detection and warning system placed upstream from an I-80 work zone decreased the highest 15 percent of vehicle speeds by about 5 mi/hr as vehicles approached the work zone lane merge area.

Evaluation of the SpeedGuard Radar Speed Reporting System in Nebraska

May 2000
Lincoln; Nebraska; United States

Summary Information

This study evaluated the impact of deploying a portable speed warning sign to control traffic speeds in work zones by informing vehicles of their speed in relation to posted speed limits on interstate I-80 in Nebraska. The SpeedGuard Radar Speed Reporting System was deployed on the shoulder of a two lane freeway about 1,250 feet in advance of a work zone. The system consisted of a self contained battery powered trailer unit equipped with a speed radar and a 24-inch two digit LED speed display. The left lane was restricted and vehicles were merged into the right lane ahead of the work zone.

Pneumatic vehicle counter/classifiers were installed approximately 500 feet and 1500 feet in advance of the work zone lane closure in order to track vehicle speeds, speed distribution, and vehicle length before and after system deployment. Between August 18 and August 21, 1999, traffic data was collected to evaluate vehicle speeds "with" and "without" the radar warning sign in operation. Due to technical difficulties, the system was periodically disabled during the experiment and only 7 hours of "with" data were able to be collected. Thus, the before data, and the data collected while the unit was shut off were combined for a total of 58 hours of "without" data. In addition, only data collected during periods of uncongested flow (greater than 35 mi/h) were used in the evaluation.


The SpeedGuard system decreased driving speeds and increased speed uniformity as traffic approached the work zone. At a location 500 feet in advance of the lane closure taper, which was 750 feet downstream from the SpeedGuard system, the 85th-percentile speed and mean of the highest 15 percent of speeds were reduced significantly by about 5 mi/hr. The system effectively lowered the values of these parameters to speeds below or equal to the speed limit.


This study is a part of series of studies carried out as part of the Midwest Smart Work Deployment Initiative.

Benefit Comments

No comments posted to date

Comment on this Benefit

To comment on this summary, fill in the information below and click on submit. An asterisk (*) indicates a required field. Your name and email address, if provided, will not be posted, but are to contact you, if needed to clarify your comments.


Midwest States Smart Work Zone Deployment Initiative: MwSWZDI Technology Evaluations Year One - Chapter 5: Nebraska - SpeedGuard Radar Speed Reporting System

Author: Maze, T., et al.

Published By: Mid-America Transportation Center, University of Nebraska

Prepared by Iowa State University, The University of Kansas, University of Missouri-Columbia, and the University of Nebraska – Lincoln

Source Date: May 2000



Average User Rating

0 ( ratings)

Rate this Benefit

(click stars to rate)

Goal Areas


Typical Deployment Locations

Rural Areas


smart work zone systems, smart work zone, smart work zones, Smart work zones, workzone, WZ, automated enforcement, Smart work zone, Portable Dynamic Message Sign, Portable DMS

Benefit ID: 2003-00262