Cobb County DOT: Cooper Lake Road at King Springs Road
Service Details
Surveying
Route surveying performed in preparation of Base Map for design of intersection improvements for Cooper Lake Road at King Springs Road in Cobb County. SEI obtained right of way plans, deeds, plats and other pertinent information for project planning and for future right of way resolution. SEI utilized survey grade GPS units to establish survey control throughout each route for Vertical (MSL) and horizontal control. These control points were confirmed for accuracy by running a level loop on each route. A robotic total station was utilized to gather the data required for the Base Map. These include; topography, creeks, streams or ditches, storm water and sanitary sewer pipes and associated structures, curb, gutter, pavement, striping, traffic control devices, all above ground visible utilities, property corners, right of way markers and any unusual features. Information gathered was then processed and verified for accuracy, imported into CAD format. Analysis of the right of way was performed and resolved. The Base Map was then provided in Microstation format for our Transportation Department to begin conceptual design.
Transportation Engineering
SEI designed a roundabout at this intersection for CCDOT. An intersection improvement was warranted due insufficient stopping sight distance approaching from the North along King Springs Road and an insufficient sight distance looking right approaching the form the South along King Springs Road. Additionally, the horizontal alignment of Cooper Lake Road has a non AASHTO standard curve for the current speed design. The roundabout has been placed on the centerline of Cooper Lake Road. The Northbound approach on King Springs Road will remain offset slightly to the left of the center of roundabout to keep cost associated with this project within budget. The Southbound approach on King Springs Road will be re-aligned to offset this approach to the left to allow for more deflection so as to provide a safer roundabout. This project was designed by a modified GDOT Plan Development Process for CCDOT.
Traffic Engineering
The purpose of the intersection improvement for King Springs Rd and Cooper Lake Rd was to improve the traffic operations and enhance the safety of this intersection. As part of the efforts of the project, a traffic study was performed for the existing unsignalized intersection of King Springs Rd and Cooper Lake Rd. The study analyzed the existing conditions to determine the traffic operations and safety of the intersection. The intersection was also evaluated in the future conditions to determine the capacity requirements for a 20 year design to function at an acceptable level of service. The findings of the study were that the intersection had insufficient stopping sight distance approaching from the north along King Springs Road and insufficient entering sight distance for the northbound approach of the intersection. Additionally, the horizontal alignment of Cooper Lake Road has a non AASHTO standard curve for the current speed design. Based on the existing safety concerns and the future capacity needs, the roundabout was determined to be the best solution to provide safe and efficient traffic flow.
