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Ramp Meters

What they are, why we have them and what we've learned

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Twin Cities Metro Area Ramp Meter Study FAQs

 

Oct. 2000 FAQs

 

 

When will the shutdown occur?

The ramp-meter study that includes shutting off all ramp meters in the metro area will occur starting with the morning rush hour on Monday, October 16 and last from four to six weeks. The shutdown follows completion of a five week pre-study data collection effort which began on September 12. The pre-data collection was done to enable the consultant to compare the data collected "with" ramp meters against the data collected "without" ramp meters. Data analysis is expected to be complete by the end of the calendar year.

 

Will all the ramp meters be turned off?

Yes, all 430 ramp meters will be shut off during the study.

 

Why did you decide to tell the public about when the shutdown would occur?

The Ramp Meter Study Advisory Committee decided to notify the public a week in advance of the shutdown. The consultant decided that they will take into account the impact of any type of anticipatory behavior. The consultant estimates that it will take one to two weeks for traffic to settle down when the meters are turned off. The consultant believes that alerting the public could speed up this transition time.

 

What will the study cost?

The study will cost $651,600.

What are the study objectives?

Study objectives include:

 

What will the consultant be measuring?

The consultant will study four freeway corridors that have been chosen as being representative of the system. The location of these corridors will not be made public, so as to maintain the integrity of the data. The consultant team will collect data that will help it evaluate the impacts of ramp metering on travel time, safety, travel time reliability/predictability, the environment and energy and volume (the number of vehicles the system carries). This data will be collected on both freeways and parallel alternate routes. Additionally, customer satisfaction will also be measured.

 

How will the consultant measure customer satisfaction?

The consultant plans to use a series of focus groups and a telephone survey of users of the system. They will measure individual traveler-oriented perspectives regarding ramp meters and ramp meter operation. In total, 1,540 system users will participate in the market research.

 

Why is MnDOT doing this study?

A bill, passed by the 2000 Legislature, requires that MnDOT study the effectiveness of ramp meters in the Twin Cities metro area by conducting a shutdown study before the next legislative session.

 

Does MnDOT support the study?

MnDOT is fully committed to conducting a scientific study of ramp meter effectiveness.

 

Will there be citizen/community involvement in the study?

Two committees are helping to guide and implement the study to ensure the involvement of a broad range of stakeholders.

 

Is the consultant taking into account the changes in weather or lighting conditions that will occur in the before and after study? What about days with a high number of incidents?

 

Will the High Occupancy Vehicle (HOV) lanes and ramp-meter bypasses be open to single-occupant vehicles during the study?

The consultant intends to flag bad weather days (rain/snow), high incident days, and dark vs. light conditions (both during the "before" and the "after" data collection). Incidents are defined as crashes, stalled or stranded vehicles, and obstacles, such as spilled cargo. The data will be grouped and analyzed into separate categories. If there is a statistically significant difference between groups, the data will be analyzed separately and comparisons will be made for data under similar weather/light/incident conditions. Also, the consultant will analyze data across groups to identify differences in the effectiveness of ramp metering under varying weather/light/incident conditions.

 

What will the ramp meters look like during the study?

No. The HOV lanes and ramp-meter bypasses will operate as usual and will be open for buses, car/vanpools, and motorcycles during regular hours. The State Patrol will enforce these lanes and bypasses as usual.

 

If the system collapses, will MnDOT stop the study?

The study is a legislative mandate and MnDOT plans to carry out the study to its completion. There is a plan in place, however, should consideration need to be given to stopping the study mid-way through its completion, due to circumstances such as safety.

 

What do you think will happen when the ramps are shut down?

It would be inappropriate for MnDOT to speculate as to what will occur when the meters are shut off.

 

Can I comment about the study?

During the study an online comment form was available.

 

Are there other cities with ramp meters in operation?

The largest ramp metering system in North America is located in Los Angeles County with more than 1000 meters. Since 1989, the number of meters (nationwide) has increased from about 1,600 to about 2,300. By the end of 1999, at least 33 metro areas have meters operating, including: (Source: Ramp Metering in North America - 1995 Update, Federal Highway Administration,. June 1995)

 

Metropolitan Areas with
more than 50 meters

Metropolitan Areas with
less than 50 meters

Chicago, IL
Los Angeles, CA
Minneapolis/St. Paul, MN
New York, NY
Orange County, CA
Phoenix, AZ
Portland, OR
San Diego, CA
San Jose/San Francisco, CA
Seattle

Atlanta, GA
Columbus, OH
Denver, CO
Detroit, MI
Fresno, CA
Houston, TX
Milwaukee, WI
Northern Virginia, VA
Riverside, CA
Sacramento, CA
San Antonio, TX
San Bernardino, CA
Toronto, ON

 

Where did ramp metering start in the country? In Minnesota?

Ramp metering has been around since 1963 when it was first installed on the Eisenhower Expressway (I-290) in Chicago. This first application involved a police officer who stopped traffic on an entrance ramp and released vehicles one at a time at a predetermined rate.MnDOT first installed meters in 1969 on I-35E. These were located on entrance ramps at Maryland Avenue and Wheelock Parkway in St. Paul.


How many ramp meters have been installed since then?

Yearly Ramp Meter Installation Count

1970 = 4
1971 = 2
1972 = 0
1973 = 0
1974 = 4
1975 = 33
1976 = 0
1977 = 0
1978 = 0
1979 = 11

1980 = 0
1981 = 0
1982 = 0
1983 = 0
1984 = 4
1985 = 7
1986 = 0
1987 = 0
1988 = 2
1989 = 67

1990 = 85
1991 = 64
1992 = 49
1993 = 41
1994 = 24
1995 = 0
1996 = 1
1997 = 0
1998 = 21
1999 = 8
2000 = 0

 

What are the objectives of ramp metering?

There are three broad objectives for ramp metering:

Minnesota has adopted the second objective.

 

Have evaluations of the effectiveness of ramp meters been done anywhere?

Some evaluations are relatively new (Houston and Atlanta), while others were performed over 15 years ago (Los Angeles, Portland and Sacramento) (most of MnDOT’s corridor specific evaluations were done in the late 70’s and early to mid ‘80’s. The results of those evaluations mirrored those shown in the table below).

Generally, there hasn’t been a great deal of difference in the findings of those individual evaluations despite the time separation.

Performance Measure

Location & Result

Travel time

Atlanta – 10% decrease in peak period
Houston – 22% decrease in peak period
Arlington – 10% decrease in peak period

Travel speed

Milwaukee – 35% increase in peak period
Portland –155% increase in peak period
Los Angeles – 15 miles per hour faster

Crash rate

Phoenix – 16% decrease during metered hours
Milwaukee- 15% decrease in peak period

Crash frequency

Portland –43% decrease
Sacramento – 50% decrease
Los Angeles – 20% decrease

Driver hours saved

Sacramento – 50% decrease
Los Angeles – 8,470 hours per day

Vehicle volume

Milwaukee – 22% increase in peak period
Sacramento – 5% increase in peak period
Los Angeles – increase of 900 vehicles per day

Gallons of fuel saved

Portland – 700 gallons per weekday

Benefit/Cost ratio

Atlanta – about 4:1 in year 1, about 20:1 after five years

 

Why do we have ramp metering? What function does it serve?

Ramp metering is one method of maximizing existing roadway capacity. Other reasons for ramp metering include:

How much did MnDOT spend to install and perform any needed upgrades/replacements at the 430 ramps that are metered?

Since 1970, MnDOT has spent a total of $3,170,300 to install and perform any needed ramp meter system upgrades.

 

If the 430 ramp meter system were to be installed today, what would it cost?

To install the 430 ramp meter system today would cost approximately $4.2 million or $9,600 per ramp.

 

Doesn't MnDOT's traffic management and traveler information system include more than just ramp metering? How much has that cost?

MnDOT's traffic management, incident management, and traveler information system is a comprehensive network which includes closed circuit television cameras, a fiber optic communications system, changeable message signs, real-time traveler information delivery systems (including the internet and broadcast radio and television), lane control signals, a computer system, automated data collection and detection, control room monitor and display equipment, Highway Helpers, the Traffic Management Center and ramp meters. Since 1970, MnDOT has spent approximately $54,250,000 to install, upgrade and expand that system to a point where it now manages the flow of traffic on approximately 210 miles of freeways in the Twin Cities metropolitan area.