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Planning Guidance for the Installation and Use of Technology Devices for Transportation Operations and Maintenance

ENTERPRISE Transportation Pooled Fund Study

Ramp Meter Guideline 2 - Localized Freeway Traffic Issues

NOTE: The majority of this isolated intersection ramp meter warrant was originally developed by ITS Engineering and Constructors, Inc. on behalf of Arizona Department of Transportation, published as ‘Ramp Meter Design, Operations, and Maintenance Guidelines.

Purpose: To address the need for an isoloated Ramp Meter deployment, that is not part of an overall corridor ramp meter approach.

The planning guidelines for ramp meters are presented as one tool to assist agencies in selecting deployment locations, and are not a replacement for the planning or design process.  Also, prior to deploying a ramp meter  System, ensure the basic requirements of the MUTCD (2009 Edition Chapter 4I. Traffic Control Signals for Freeway Entrance Ramps) have been met at the location of concern.

Engineering judgment should be used to assess potential implications that may result from installation of ramp meter.  This planning guidance does not mandate the use of ramp meters.

 

1a. The freeway operates at speeds less than 50 mph for a duration of at least 30 minutes for 200 or more calendar days per year. (1)

OR

1b. There is a high frequency of crashes (collision rate along the freeway exceeds mean collision rate in the subject metropolitan area) near the freeway entrances because of inadequate merge area or congestion? (1)

OR

1c. The ramp meter will contribute to maintaining a specific level of service (LOS) identified in local transportation plans and policies. (1)

OR

1d. The ramp meter will contribute to maintaining a higher level vehicle occupancy through the use of HOV preferential treatments as identified in the region’s transportation system management (TSM) plan. (1)

OR

1e. The ramp meter will contribute to balancing demand and capacity at a system of adjacent ramps entering the same freeway facility. (1)

OR

1f. The ramp meter will mitigate predictable sporadic congestion on isolated sections of freeway because of short peak period loads from special events or from severe peak loads of recreational traffic. (1)

AND

2a. The Total Mainline-Ramp Design Hour Volume (mainline volume plus ramp volume) exceeds the following: (3)

• Two mainline lanes in one direction – 2,650 (vph);
• Three mainline lanes in one direction – 4,250 vph;
• Four mainline lanes in one direction – 5,850 vph;
• Five mainline lanes in one direction – 7,450 vph;
• Six mainline lanes in one direction – 9,050 vph.
  

OR

2b. The total volume of the sum of traffic in the right most lane and the ramp exceed 2100 vph during the design hour. (3)

OR

2c. Platoons from signalized intersections are recognized to adversely impact the ramp in consideration. If hourly volume, based on maximum 30 second volume readings projected to hourly values, exceed 1100 vph. (regardless of overall hourly volume). (4)

Note: Overall hourly volume entering from arterials may be relatively low (e.g. 700 vph). However, during periods when platoons arrive, if 30 second readings of volumes represent 1100 vph or greater, this factor is considered met.

AND

3. Functionality Factors. Volumes at ramps being considered for meters, within the zone, fall within the range of 240 – 900 vphpl during peak periods. (2)

Note: The length and geometry of the ramp is a factor in the final decision of whether to deploy a ramp meter. The current guideline for ramp meters does not address this factor, as it is believed the analysis of the ramp will be a part of the preliminary and final design. The focus of the guideline is on whether or not a ramp meter is needed, not on whether a ramp meter can be designed at the location, as that would be determined during the design process.

References:

(1) Federal Highway Administration. 2003 Edition, Manual on Uniform Traffic Control Devices. 2003.
(2) Caltrans, Traffic Operations Program. Ramp Meter Design Manual. 2000.
(3) Kimley Horn & Associates. Arizona Department of Transportation, Freeway Management System, Design Guidelines. 2002.
(4) Mn/DOT. Discussions re: Ramp Meter Warrants Development Process. 2009.