April 20, 2012 Presented by: Clay Harris, PMP - City of Austin Federico Mendoza, PE, PTOE Brown & Gay Engineers, Inc. Todd Lane Alternative Geometric Design Study Ben White to St. Elmo Austin, Texas Project Background Todd Lane Alternative Geometric Design Study Austin, Texas 2 Need Widen Todd Lane to accommodate additional traffic flows from Pleasant Valley Begin 4-lane divided arterial roadway design and real estate acquisition Design Water Quality ponds at each end of the project to drain into the Williamson Creek and Country Club West Watersheds Existing Conditions Surrounding land use North: mix of light industrial and office space South: residential single-family homes and multi-family units Roadway characteristics Todd Lane: two-lane roadway with open ditches and a posted speed limit of 35 mph St. Elmo Road: two-lane roadway east of Todd Lane and transitions into a four-lane undivided roadway west of Todd Lane Project Goals Project Goals: Enhance Vehicular, Pedestrian & Bike Safety Maintain acceptable Level of Service Improve Corridor Appearance Stimulate Revitalization Preserve precious water resources (i.e. drainage to streams, lakes, and aquifers) Maintain Commercial Activity during construction 4 Proposed Project Todd lane Water Quality Rain Gardens Watershed Protection Department, Sustainable Storm Water Solutions Section Required criteria of any proposed strategy: capture and isolate storm water runoff for treatment, release the treated volume in 48 hours Design: 10 rain gardens and one partial sedimentation/biofiltration pond. captures storm water, provides filtration and natural infiltration, which provides water for plants within the gardens, maintains constant water flow to streams, help filter out pollutants. Proposed Project Todd Lane Alternative Geometric Design Study City of Austin engaged Brown and Gay Engineers, Inc. to conduct study to evaluate the following alternatives: Todd Lane and St. Elmo Road as standard signalized intersection with traditional 4-lane arterial plus continuous left turn center lane pavement section for Todd Lane. Todd Lane and St. Elmo Road as a modern roundabout with a three lane arterial pavement section for Todd Lane Original Project Design Alternative 1 4-lane divided on Todd Lane 4-lane divided boulevard on Pleasant Valley Road Standard signalized intersection at Todd Lane and St. Elmo Road Real Estate acquisition cost prohibitive (2.5 M), substantially delaying project schedule. Todd Lane Alternative Geometric Design Study Austin, Texas 7 Alternate Design Alternative 2A 3-lane roadway section on Todd Lane 4-lane divided on Pleasant Valley Road; Single-lane NB approach Single-lane Roundabout at Todd Lane and St. Elmo Road Fits within existing ROW Todd Lane Alternative Geometric Design Study Austin, Texas 8 Todd Lane Alternative Geometric Design Study Austin, Texas Roundabout Benefits Improved pedestrian and vehicular safety Elimination of left-turn, head-on, and T-bone collisions Vehicle-vehicle conflicts decreases from 32 to 8 Crash reduction: 90% fatal crashes, 76% injury crashes, 35% overall Yield operation promotes minimal queuing Significant reduction in delay Opportunity for community landmark 9 Todd Lane Alternative Geometric Design Study Austin, Texas Roundabout Study Scope Traffic Volumes Single-Lane Roundabout Concept Layout Two-Lane Roundabout Concept Layout Truck Vehicle Paths Traffic Simulation Analysis Conclusions 10 Traffic Volumes Existing Peak Hour Volumes Todd Lane at St. Elmo Rd. AM Peak: Heavier Volumes PM Peak: Relatively Balanced Flows Todd Lane Alternative Geometric Design Study Austin, Texas 11 Approach AM Peak Hour (Vehicles per hour) PM Peak Hour (Vehicles per hour) Northbound-- Southbound Eastbound Westbound Total1,4361,324 Traffic Projections Derived from Existing Counts and CAMPO Estimates Daily Traffic Volume Forecasts Todd Lane at St. Elmo Road Todd Lane Alternative Geometric Design Study Austin, Texas 12 Intersection Leg 2015 Daily Volumes (Vehicles per day) 2025 Daily Volumes (Vehicles per day) 2035 Daily Volumes (Vehicles per day) North11,10014,00018,000 South11,40015,40015,500 East3,3705,5187,000 West9,1008,5007,900 Todd Lane Alternative Geometric Design Study Austin, Texas Single-Lane Roundabout Concept Google Todd Lane Alternative Geometric Design Study Austin, Texas WB-50 Design Vehicle 14 Todd Lane Alternative Geometric Design Study Austin, Texas WB-50 Design Vehicle 15 Traffic Simulation Results Year 2025 Todd Lane Alternative Geometric Design Study Austin, Texas Peak Hour PeriodApproach Delay (sec/veh) Alternative 1Alternative 2A Standard Intersection Single Lane Roundabout AM PEAK Northbound Southbound Eastbound Westbound ALL PM PEAK Northbound Southbound Eastbound Westbound ALL Traffic Simulation Results Year 2035 Todd Lane Alternative Geometric Design Study Austin, Texas Peak Hour PeriodApproach Delay (sec/veh) Alternative 1Alternative 2B Standard Intersection Two Lane Roundabout AM PEAK Northbound Southbound Eastbound Westbound ALL PM PEAK Northbound Southbound Eastbound Westbound ALL Vissim Micro-simulation: 2025 AM Peak Todd Lane Alternative Geometric Design Study Austin, Texas 18 2025 AM Peak Signal vs. Roundabout Todd Lane Alternative Geometric Design Study Austin, Texas 19 Alternative Design Recommendations The single-lane roundabout will provide: Acceptable level of service through year 2025 during peak hours Least amount of delay to motorists during off-peak hours Higher level of safety (reduction in crashes) for vehicles Higher level of safety for pedestrians and bicyclists A safe and efficient alternative to a standard signal that will fit within the R.O.W. footprint Todd Lane Alternative Geometric Design Study Austin, Texas 20 Water Quality Recommendations Rain Gardens Incorporate gardens to catch and store rainfall for short periods Plant native & adapted landscape plants that are naturally drought tolerant and resistant to pests. Increase base flow (the constant flow in a creek) while decreasing the chances of flooding and stream bank erosion. Project Budget 22 Conclusions The single lane roundabout alternative will provide efficient operation by reducing delay and improving safety It will accommodate pedestrians and bicycles The single lane roundabout alternative will result in significant cost savings to the City from reduced ROW and construction costs. Rain Gardens also help maintain a constant flow of water to our streams and help filter out pollutants including fertilizers, pesticides, oil, heavy metals, and other chemicals that would otherwise reach our creeks through existing drainage infrastructure. Questions? Federico Mendoza, PE, PTOE, Brown & Gay Engineers, Director of Traffic Engineering Phone Clay Harris, PMP, Project Manager, City of Austin, PWD Phone Design Team Carlos Garcia, PE, Engineer C, City of Austin, Engineering Services Division Phone John Garza, EIT, Graduate Engineer B, City of Austin, Engineering Services Division Phone Tom Franke, EIT, Graduate Engineer B, City of Austin, Watershed Protection Department Phone