Lane Conversions

4 Lane to 3 Lane Conversions

If you’ve driven on portions of Junction Avenue in Sturgis; or Canyon Lake Drive, Sheridan Lake Road, or Fairmont Boulevard in Rapid City, you’ve experienced three-lane roadways with similar average daily traffic counts to Jackson Boulevard in Spearfish.

The conversion from 4-lanes to 3-lanes on Jackson Boulevard in Spearfish has been analyzed and recommended by the traffic engineers hired to analyze daily traffic counts, traffic flow, and safety.

3 Lane Configuration

From a traffic standpoint, the three-lane configuration works very similar to the four-lane now. The three-lane configuration would provide a level of service similar to the current configuration.

Many older four-lane roadways in communities were initially overbuilt and for safety reasons are now being reduced to three-lanes.

Change Street Configuration

The conversion would not change the street configuration to 3 lanes for the entire length of the project. The current configuration of five lanes at the intersection of Main Street and Jackson Boulevard would remain the same, except that the right lanes would be right turn only.

Reducing the number of lanes is not due to any expansion of building construction along the edges of the street. The right-of-way will remain the same width.

Pros of Reduced Lanes

The pros of the reduced lanes include:

  • Additional space for other uses or items within the right-of-way
  • Improved green space and aesthetic
  • Improved pedestrian environment and safety and improved bicyclist accessibility
  • Improved safety: Studies have shown overall crash reductions on average of 30%
  • Reduces the following accident types:
    • Left turning motorists getting rear-ended
    • Hidden vehicle crashes. (Left turning vehicles and vehicles in the opposing right lane unable to see each other due to traffic in the left lane)
    • Side swipes. (Lane changes)
  • Reduced speeds and traffic calming

Cons of Reduced Lanes

The cons of the reduced lanes include:

  • Initial public reaction, with cities completing the conversion noting initial negative reaction since it seems logical that eliminating a lane reduces traffic capacity/increases delays
  • Potential negative impacts to roadway function if the roadway is not evaluated properly to determine vehicular mobility and access, including average daily traffic, peak hour volumes, and peak direction, turning volumes, and patterns
Lane Conversions