Ramp Metering

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