Summary
Geometric Design - The foundation established in preliminary design using State and Local Design Standards is critical in development of final geometric and design details. AMT defines all elements of geometric design on roadway plans, typical sections, and cross-sections. Detailed design is required for Radii Returns at Intersections: Appropriate vehicles are accommodated in design, and AutoTURN vehicle turning movement modeling program is used to evaluate complicated projects; Islands/Raised Medians: Based on roadway geometry and lateral offset requirements, stations and offsets for these features are developed. Taper rates are set from design speed. Turn lane length is determined by traffic analysis; Sight Distance Evaluation: Vertical curvature is set to ensure proper site distance, and intersections/interchanges meet AASHTO requirements; Superelevation Transitions: Required lengths are determined based on design speed, degree of curvature, and pavement widths; Vertical Alignment: Profiles meet AASHTO criteria, and spline grades are used in pavement overlay areas.
Roadside Design - AMT focuses on Traffic Barriers: Trees, utility poles, embankments, and other roadside features are hazards to errant vehicles. Where removal is not feasible, traffic barriers are appropriate. Roadside Slopes: For steep embankment slopes that require metal barrier, it is desirable to flatten the slopes to 4:1 and eliminate the barrier. However, ROW and wetland impacts may become issues.
Resurfacing and Restoration - AMT prepares plans for maintenance, repair, and overlay (system preservation) of existing roadway. Design addresses guardrail adjustments, existing end section replacement with crash tested assemblies, inlet repair, reconstruction, & similar items common to these projects.
Design Exceptions - During preliminary design, identification and pursuit of design exceptions occurs for elements for which AASHTO criteria cannot be met due to physical or environmental constraints or as part of commitments made during project planning. All supporting data for the formal submittal is developed.
Signing/Pavement Markings - Preparation of final signing and fabrication sheets using Signtools, preparation of structure input sheets/cross-sections for all overhead mounted signs; preparation of cost estimates; and detailed final plans with sign locations, sizes, message, color, mounting type, designation, quantities, and special provisions. Pavement markings utilize the 1" = 30' scale plan sheets and are prepared using the appropriate standards. Pavement marking plans show location, size, color and material type of all pavement markings.
