- Army Installation Traffic Studies
We conducted a traffic study evaluating capacity, geometry and safety issues on six major arterials at the Fort Sill Army Installation. The study addressed 40 intersections on the heaviest traveled roadways on post. The project involved field investigations, safety reviews, traffic counts, capacity analysis, traffic signal timing, recommended lane configurations and geometry, as well as rough order of magnitude (ROM) costs to optimize or improve the flow of traffic.
During early stages of the project, on-site field investigations obtained peak hour traffic data and examined the layout and operations of each intersection. We coordinated with Fort Sill Master Planning to review and update information regarding future construction projects that might impact travel patterns and traffic volumes throughout the Installation and to gather data on current population and deployment figures. With this information, our team estimated future traffic volume demands and evaluated capacity and operational characteristics for each of the 40 intersections. Based on this information, recommended improvements were developed for implementation at 19 of the 40 evaluated intersections. ROM cost-estimate ranges were developed for each of the intersections with recommended infrastructure improvements.
Data sheets were prepared for each intersection to summarize important information: ROM cost; concept plan illustrating the recommended improvements; written descriptions of the improvements; intersection control; posted speed; traffic volumes; level of service information; and other design considerations.
Access Control Point Studies
Previously, we completed traffic engineering studies associated with the design of access control points (ACPs) based on a 2009 directive. These studies helped ensure ACP designs meet the installation's needs and satisfied ACP priorities and functions while accommodating development plans. They were subject to review and approval of the Surface Deployment and Distribution Command - Transportation Engineering Agency (SDDCTEA) as well as the U.S. Army Corps of Engineers Protective Design Center (PDC).
At Fort Sill, we completed a TES addressing this new requirement for two new ACPs. The project involved upgrades to four ACPs: Bentley ACP, Scott ACP, Key West ACP and Key East ACP. The Bentley and Scott ACPs were designed as new fully compliant ACPs meeting current Anti-Terrorism/Force Protection (ATFP) and Army ACP SD/C. We provided roadway design adjacent to the entry control facilities at Key West and Key East ACPs with consideration of speed management solutions.
The Bentley and Scott ACPs are the two busiest of the six existing ACPs at Fort Sill. On the south perimeter of Fort Sill, these ACPs are open 24 hours a day, seven days a week, providing access for military personnel and visitors. Complicating the geometry of the ACPs are two partial cloverleaf interchanges providing access to/from U.S. Route 62 (Rogers Lane) along the south perimeter of Fort Sill at the northern boundary of Lawton.
Early in the project, our team conducted a design charette, bringing stakeholders together to initiate the project and to share ideas, issues and concerns. We obtained traffic counts and sketched lane configurations of the ID check lanes and adjacent intersections.
- On-site field investigations
- Traffic counts
- Traffic projections
- Traffic capacity evaluation
- Traffic signal timing
- Recommended geometric improvements
- Recommended capacity improvements
- Recommended signal timing improvements
- Concept plan drawings of the recommended improvements
- Rough order of magnitude cost estimates
A key component to projecting traffic volumes for the ACPs involved coordination with Fort Sill Master Planning to obtain information about future projects at the installation as well as current deployment figures. According to Fort Sill planners, 40 projects were planned, and 21 of them were expected to impact traffic volumes at the ACPs. Detailed descriptions of the planned locations and missions as well as estimated numbers of personnel and staff associated with each of the projects were developed and presented in the TES. New traffic generated by each future project was superimposed upon the existing morning and evening peak hour traffic. Entering trips were assigned to each ACP based on the location of the future project.
Once traffic projections were finalized, we determined the number of ID check lanes in accordance with the directive from the Corps of Engineers Center of Standardization. In fulfillment of the Army's Office of the Provost Marshal General criteria for traffic studies described in the Army ACP SD/C, we also calculated existing and future lane requirements per SDDCTEA Pamphlet 55-15, Traffic and Safety Engineering for Better Entry Control Facilities. This was accomplished using the Access Control Point/Entry Control Facility Security, Manpower, Automation, Roads and Lanes, Traffic and Safety Decision Evaluator (SMART Decision Evaluator).
Several alternates were developed for the Bentley and Scott ACPs employing various combinations of ID check lanes, processing technology and manpower levels. These alternates were compared with the objective to maximize security, safety and traffic operations while minimizing manpower needs and infrastructure costs. Decision matrices were prepared detailing information about each option including lane configuration, manpower needs, resultant traffic queues, associated risk scores and infrastructure costs. Each alternative was given a weighted score for each category and a final rank.
After the preferred alternatives were selected, we prepared detailed ACP layouts and associated threat calculations. These layouts and calculations were included as appendices to the TES. Manpower requirements were evaluated with the SMART Decision Evaluator for the two ACPs during peak and off-peak periods under current and future traffic conditions. Adjacent intersection operations were also evaluated in consideration of current and future traffic volumes during the peak periods. HCS+ software was used to calculate a level of service for the intersections based upon average delays experienced by vehicles moving though the intersections. In addition to operations, it was critical to ensure lines at the intersection approaches would not interfere with the active vehicle barrier locations.
SDDCTEA Pamphlet 55-15 recommends implementing a comprehensive guide sign plan at installations with two or more ACPs. As part of the TES, we evaluated existing guide signs outside the ACPs at Fort Sill, comparing them to criteria in the Manual on Uniform Traffic Control Devices. We recommended guide sign improvements to enhance the processing capability of the ACPs.