Ramp metering

This ramp control project extends along southbound I-35E from Little Canada Road to Maryland Ave. (see map on page 5). Pre-timed ramp control signals were activated at Maryland Ave. and Wheelock Pkwy. in October, 1970. Traffic responsive ramp control signals were activated at Roselawn Ave., T.H. 36 (leg and loop of cloverleaf) and Little Canada Road in November, 1971. At the same time the pre-timed ramp control at Maryland Ave. and Wheelock Pkwy. was revised to include traffic responsive features. Each ramp controller operates on an isolated basis with no interconnect to other interchanges. The system usually operates from about 7:00 to 8:00 A.M., Monday thru Friday. This report presents an evaluation of the first seven years of system operation. The following data were gathered: 1. Freeway volumes, speeds, travel times, and accident experience. 2. Entrance ramp volumes, delays, and ramp control violation rates. 3. Alternate route volumes and travel times. 4. System maintenance records. 5. Information on comments from drivers.

Mn/DOT's traffic management efforts began with the implementation of isolated ramp metering on I- 35E. Recurring congestion began on southbound I-35E north of the St. Paul central business district shortly following the opening of St. Paul's Capitol Interchange in 1967. In 1969, Mn7DOT conducted a two-week experiment with pre-timed ramp control signals on southbound I-35E at Maryland Avenue, Wheelock Parkway and Roselawn Avenue. This experiment was successful and permanent, pre-tuned (or isolated) ramp meters were installed at Maryland Avenue and Wheelock Parkway as a result. An evaluation of this system showed improved traffic flow with no significant negative impact on the parallel arterial streets. The system was expanded and upgraded in 1971. Successful operation of the I-35E system led to the development of the I-35W Urban Corridor Demonstration Project in 1974. This project combined the advantages of freeway traffic management and "freeway flyer" express bus service and provided the first extensive demonstration of the bus-on-metered- freeway concept. The bus-on-metered-freeway system provided buses with priority access to the freeway via exclusive bus ramps. The project also included installation of a traffic management system on 1-94 in the Lowry Hill tunnel area.

Mn/DOT (Minnesota Department of Transportation) activated a traffic management system on a three mile section of I-694 in August 1980. System elements include vehicle detectors, ramp control signals, a changeable message sign, and monitor and display devices. Evaluation of this system was complicated by a reconstruction project on I-694. Study results showed that there were improvements in traffic flow and accident experience even though peak period volumes increased substantially. These improvements are attributed to the combined effects of the traffic management system and the reconstruction project. Despite the improvements, there is a need for additional capacity in the I-694 corridor, and projects intended to accomplish this are briefly described.

This report details the results of a study on the traffic flow and safety impacts of ramp metering, and it meets the legally mandated deadline of February I, 2001. It is the result of a study that was conducted in an independent and objective manner by a nationally recognized consultant team at a cost of $651,600. The study served two important public purposes: 1) It thoroughly documented the benefits resulting from ramp metering to traffic operations and related factors such as air quality in the Twin Cities metro region. Analysis of field data indicates that ramp metering is a cost-effective investment of public funds for the Twin Cities area, 2) It demonstrated the need for Mn/DOT to adjust its approach to ramp metering in a way that will optimize benefits while conforming to public expectations. Analysis of market research data shows that a clear majority of users of the Twin Cities metro region highways support continued operation of ramp meters as a congestion management tool in some modified form. The combination of these two factors point towards the adoption of an overriding principle regarding the operation of ramp meters in the Twin Cities. This principle would seek to "balance the efficiency of moving as much traffic during the rush hours as possible, consistent with safety concerns and public consensus regarding queue length at ramp meters."

In 1990, the Minnesota Department of Transportation, (Mn/DOT) contracted with the University of Minnesota Center for Survey Research for a survey of public attitudes and opinions concerning various transportation related issues. Two surveys were conducted. There was a Statewide Omnibus Surrey in which the transportation portion included a variety of maintenance related questions. In addition, a Twin Cities Area Survey was undertaken which focused on information and ramp metering on Twin Cities freeways.

This study is a direct follow-on from the results of a Congestion/Road Pricing Study conducted by Wilbur Smith Associates (WSA), in association with SRF Consulting Group (SRF) in 1997. The Congestion/Road Pricing Study evaluated the potential impacts of and public opinion related to a congestion road pricing program in the Minneapolis-St. Paul area and of a statewide vehicle mileage tax. The study concluded with identification of key issues regarding possible road pricing. As a result of the Congestion/Road Pricing Study, a proposal for adding capacity through high occupancy toll lanes was made. This new study, Toll Lane System Preliminary Feasibility Study, was commissioned to evaluate the impacts of a series of added-capacity lanes on most freeways in the Minneapolis-St. Paul metropolitan area. An extensive market research program was also carried out to identify public reaction to the policy and operational aspects of pricing on new capacity in order to define a Communications Plan for Mn/DOT's ongoing Congestion Relief Toll Lane System Initiative. The region's plan is to promote transit and carpooling by adding lanes on the area's most congested freeways. The added capacity lanes are intended for the use of high-occupancy vehicles (HOVs) free of charge. To make maximum use of excess capacity in the HOV lanes, single occupancy vehicles (SOVs) would be allowed into the new lanes if they paid a toll. The basic system studied is based on Mn/DOT's Transportation System Plan (TSP) and Metropolitan's Council Transportation Policy Plan (TPP). Additional segments were added to the base scenario to test various concepts and alternative configurations. This study analyzed the anticipated use of the toll lanes under a variety of rates, the effect of the additional capacity on adjacent "free" lanes, and operational implications of such a system, and estimated system costs and revenues. In addition, a ramp meter bypass buy-in program was also analyzed.

The Capitol Approach Interchange in St. Paul was opened in November 1969, providing a through route for southbound I-35E traffic into the downtown area and to the east and west on I-94. Beginning in the summer of 1968, traffic volumes on I-35E southbound during the morning peak hour were such that congestion and delays occurred between TH 36 and I-94. Breakdowns were almost a daily certainty, with the Maryland Avenue Ramp area the most severely affected. Several factors were suspected as possible causes, including: 1. inadequate downtown ramp terminal capacity. 2. roadway geometries, generally. 3. restricted width of the Cayuga Bridge, specifically. 4. weaving traffic. 5. combination of several of the factors. In January of 1969 the Traffic Research Section sought to determine the actual cause of the congestion and to recommend relief measures This activity culminated in the I-35E Ramp Metering Study conducted in July 19&9. This report covers the first in a series of Ramp Metering studies to be conducted in the Twin City Metropolitan Area by the Minnesota Highway Department

This report, the third on ramp metering experience on I-35E in St. Paul, Maplewood and Little Canada, presents results of an evaluation of the traffic responsive system installed in 1971. The system was approved by the Federal Highway Administration as a Category II - Experimental" project. This report is intended to fulfill the requirements of the Category II approval.

The goals and objectives for evaluating ramp meter effectiveness in the Twin Cities Metropolitan Region were designed to investigate system performance and public acceptance of the new ramp metering strategy. Implemented following the shutdown - as described in Section 1.0, page 1-2. The Phase II evaluation goals include: 1. To evaluate whether the benefits of the new ramp metering strategy outweigh the impacts and associated costs; 2. To identify the impacts of the new ramp metering strategy at selected surface streets; and 3. To evaluate the impacts of the new metering strategy on freeway-to-freeway ramps. For each of the broad evaluation goals, several detailed evaluation objectives were identified. These evaluation objectives provided the framework for conducting the evaluation. Table 2.1 presents the evaluation objectives as they relate to each of the evaluation goals. The following sections describe in greater detail the tasks required to fulfill each of the evaluation's three main goals and associated objectives.

This report summarizes the final results of the research effort to develop a freeway traffic simulator with the capability to evaluate freeway operational strategies, such as traffic-responsive ramp metering and high-occupancy vehicles (HOV) lanes. Researchers first developed an efficient software data structure by adopting a dynamic memory allocation scheme to use the available memory as efficiently as possible. That work also included modifying the existing macroscopic, segment-based modeling structure and developing new types of pipeline segments to facilitate detection modeling and further model enhancements. Based on the new segment-based modeling structure, researchers developed a new simulation module to handle HOV lane traffic flows and extended the simulation procedure for an exclusive HOV lane to handle a network of freeways. Further, the simulation model also incorporates a new module to emulate the traffic-responsive ramp metering algorithm implemented by the Traffic Management Center since the 1980s. The new software structure developed in this research allows the future addition of new metering algorithms without major difficulties. To facilitate the data input process for the expanded simulation features, a new Windows-based user interface was developed using the Delphi software development tool kit. With the new user interface, most of the data input process can be done without exiting the main menu screen. Note: The phase I report is available at https://hdl.handle.net/11299/156893.