US-77 Improvements coming to Junction City
A forward thinking Interchange design referred to as Diverging Diamond Interchange will soon be constructed in District 2 as part of a series of improvements scheduled for US-77 at Junction City. In addition to the interchange, there is a widening in all directions of the Rucker Rd/US77 intersection, the eradication of Walla Walla Rd, and a widening of the southbound lanes on US77 just south of the US77/K57 four lane interchange.
The Diverging Diamond Interchange project at I-70/US-77 was let in April and construction will begin in
late June of this year. When the DDI concept was presented to the community advisory committee assisting in the development of a series of improvements coming to US-77 at Junction City, it received overwhelming support.
Just how traffic passes through the DDI is unconventional but easily understood by drivers unfamiliar
A DDI Interchange in Springfield, MO. with the design.
The DDI has many advantages over a traditional Diamond Interchange when dealing with high traffic volumes and a high percentage of tractor-trailers by reducing the number of conflict points. The benefits are:
Safety Benefits
- Fewer conflict points (14 for DDI, 26 for conventional)
- Conflict points spread out throughout interchange
- Better sight distance at turns
- Virtually no driver confusion (FHWA study and new DDI observations in Springfield, MO)
- Traffic calming features when desired
- Wrong way entry to ramps extremely difficult
- Pedestrian crossings are shorter
Supporting Data
- MODOT survey shows that 97% of drivers feel safer in the new Springfield DDI compared to the previous diamond interchange
- Crash data for the new Springfield DDI show a 60% reduction in collisions in a five-month comparison of the old interchange
- Versailles, France DDI showed that within a five-year time span that was examined, there were only been 11 reported light crashes
Operational Benefits
- Unique phase combinations
- “Free” or simple left and right turns from all directions
- Increases left turn lane capacity without needing more lanes
- Only two phases needed, shorter cycle length
- Lanes with multiple assignments in all directions
- Better storage between the ramp terminals
- More functional during a power outage
- U-turns from highway are accommodated well
- More functional during a power outage
Kansas Department of Transportation News Release
Diagram shows how traffic will pass thru a DDI Interchange