Benefit

During a 1998 snow storm, Mn/DOT reduced roadway clearance costs by 18 percent on I-90 by activating a freeway gate closure system to limit vehicle interference and reduce snow compaction problems that increase work for plows.


October 1999
Interstate 90,Minnesota,United States


Summary Information

This report evaluates the Minnesota Department of Transportation (Mn/DOT) operational procedure for restricting highway access when driving conditions are unsafe. During severe snowstorms and major incidents, mainline gates divert traffic from highways and gates located on entrance ramps prohibit highway access. Generally, Mn/DOT personnel report to gate locations and activate warning signs with amber lights. Gate arms are then swung or lowered into place and gate arm lights are illuminated. Once gate arms are deployed, law enforcement personnel man gate locations for one to two hours.

In Fall 1998 and between March and August 1999, Mn/DOT's Office of Advanced Transportation Systems conducted analyses to document past procedures and to identify current operational issues associated with gate systems. A benefit-to-cost analysis compared potential savings to estimated costs, and a winter storm case study compared costs for clearing a gated highway section to costs for clearing a section without gates.

FINDINGS

An analysis of gate operations during a severe winter storm was also performed. On November 11, 1998 a snowstorm prompted closure of Interstate 90 between the South Dakota state line and US Highway 75, while US Highway 75 remained opened between the Iowa state line and Trunk Highway 268. Comparative data from Mn/DOT reports are shown in Table 2.

Table 2: Comparison of Interstate 90 and US Highway 75

Costs
Plow Route
Lane Miles
Number of Plow Passes
Labor Hours/Miles Serviced
Labor Hours/ Lane Mile
Labor/ Lane Mile
Equipment/ Lane Mile
Material/ Lane Mile
Total/ Lane Mile
I-90
50
4
0.10
0.38
$9.08
$6.14
$4.50
$19.72
US 75
59
10
0.04
0.41
$9.98
$9.54
$4.59
$24.12


Two hundred lane miles were plowed on Interstate 90, while 590 lane miles of Highway 75 were cleared. Because Interstate 90 was closed, there was no interference from vehicular traffic and less snow compaction. Thus, the interstate was cleared to bare pavement four hours before Highway 75. As a result, total costs to clear Interstate 90 were 18 percent lower than costs to clear Highway 75.

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Source

Documentation and Assessment of Mn/DOT Gate Operations

Author: BRW, Inc.

Published By: Minnesota DOT

Prepared by BRW, Inc. for the Minnesota DOT

Source Date: October 1999

URL: http://www.dot.state.mn.us/guidestar/pdf/gatereport.pdf

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Goal Areas

Productivity

Typical Deployment Locations

Rural Areas

Keywords

automated gate closure

Benefit ID: 2001-00215