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Intersection Control Evaluation (ICE)

Purpose

Intersection Control Evaluation (ICE) is a directive issued by the California Department of Transportation (Caltrans) for all proposed highway intersection projects, whether new or for improvement. ICE is performed during the early stages of a project, allocating time to study which types of intersection control alternatives would work. Control types listed by ICE include stop, signal, roundabout and lane configuration changes. Each is to get ample time for consideration.

Need for ICE

The project site is located in a heavily traveled corridor within the city of Lake Elsinore. The interchange exit with Railroad Canyon Road serves as the main arterial between the residences of the city and major commuting routes along Interstate 15. There are significant truck routes that pass the area as well.

Step 1: Configuration Assessment/Screening

Stop Control

A stop controlled intersection involves placing stop signs at the intersection, making vehicles that pass through it have to stop and pass with caution. Based on the existing control at the intersection there is no possibility a stop controlled intersection can handle the volume and complexity of traffic going through. This alternative will not be considered in engineering analysis.

Roundabout Control

Yield control involves slowing vehicle speed to a safe level while making them pay attention to other vehicles in the intersection. One type yield control is the roundabout, a typically circular road where vehicles can enter and exit from different roads. There is enough right of way to design a traditional roundabout, possibly with an increase of interior lanes and a road diet of the surrounding area. This alternative will be considered further in engineering analysis.

Signalized Control

A signalized control uses traffic lights to coordinate movements in an intersection. The current control is of this type. A change in timing and/or coordination with other signals is likely needed. This alternative will be considered further in engineering analysis.

Step 2: Engineering Analysis of Control Alternatives

Roundabout Control

A traffic simulation was run using a traditional roundabout using yield control for entry points. Lanes from all streets were reduced to two before entering the two lane roundabout. Existing and predicted 2040 peak hour traffic volume was used. Results from this analysis concluded that the roundabout will breakdown. Therefore, this alternative will not be considered.

Signalized Control

A traffic simulation was run using a signalized control. Signals were re-implemented at this intersection, but with a change of lane configurations of the surrounding streets and a change in phasing/timing of the signal. Existing and predicted 2040 peak hour traffic volume was used. Results from this analysis concluded that signalized control can handle the input.

Other Considerations

Other intersection control methods, including left turn offsets, are likely to fail do to the need for drastic lane configuration changes and purchase of considerable right of way. It is recommended that the alternative selections be put into the study area network of intersections to gauge its effect. However, since the standalone analysis already fails, then inclusion into the network is not necessary.

Continuous Flow Interchange

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Figure 1. Overview image of the intersections under consideration, numbered 1-3. The CFI alternative replaces the encircled ramp intersections.

Evaluation Summary

Stop control, roundabout control and non-traditional control at intersections 1, 2 and 3 are not likely to work due to high volumes that are projected to exist within the life of the proposed project, year 2040. Therefore these alternatives will be rejected.

Based on an evaluation using predicted traffic conditions, signalized control for all intersections is the likely candidate to be chosen for the CFI and therefore recommended for the project.


Control Alternative Overview Table

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Diverging Diamond Interchange

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Figure 2. Overview image of the intersections under consideration, numbered 1-3. The DDI alternative replaces the encircled ramp intersections.

Evaluation Summary

Stop control, roundabout control and non-traditional control at intersections 1, 2 and 3 are not likely to work due to high volumes that are projected to exist within the life of the proposed project, year 2040. Therefore these alternatives will be rejected.

Based on an evaluation using predicted traffic conditions, signalized control for all intersections is the likely candidate to be chosen for the DDI and therefore recommended for the project.


Control Alternative Overview Table

ddi_chart

Single Point Urban Interchange

spui_map

Figure 3. Overview image of the intersections under consideration, numbered 1-3. The SPUI alternative replaces the encircled ramp intersections.

Evaluation Summary

Stop control, roundabout control and non-traditional control at intersections 1, 2 and 3 are not likely to work due to high volumes that are projected to exist within the life of the proposed project, year 2040. Therefore these alternatives will be rejected.

Based on an evaluation using predicted traffic conditions, signalized control for all intersections is the likely candidate to be chosen for the SPUI and therefore recommended for the project.


Control Alternative Overview Table

ddi_chart

For a more in-depth analysis on each alternative, follow the link below to download the Intersection Control Evaluation Reports.