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Low Impact Development Design Competition Green Roadway Design Challenge Houston Land Water Sustainability Forum December ...
Design Objectives <ul><li>Redesign a two lane road with ditches to a four lane thoroughfare in accordance with Harris Coun...
Design Assumptions <ul><li>Sample project is Independence Parkway in Harris County Precinct Two from Tidal Road to about 1...
Low Impact Design Features <ul><li>Curb and gutter section with armored curb inlets to reduce impervious cover (versus sho...
Low Impact Design Features <ul><li>Porous concrete pavers for shared use path reduce impervious cover and facilitate infil...
LID Feature:  Bio-swale & Bioretention  Green Roadway Design Challenge
LID Feature:  Pervious Pavers  Green Roadway Design Challenge
LID Feature:  Pervious Pavers  Green Roadway Design Challenge
Typical Pollutant Removal Rates with Bioretention Green Roadway Design Challenge
Estimated Filtration with Proposed Bioretention Green Roadway Design Challenge
LID Feature:  Roundabout  Green Roadway Design Challenge
Hydraulics and Hydrology <ul><li>Existing Condition  = 120 ft ROW with 44 ft of paved surface </li></ul><ul><li>Proposed C...
Hydraulics and Hydrology <ul><li>Proposed Roadway incorporates two right-of-way ditches sized to accommodate offsite flow ...
Existing and Proposed Hydrographs Green Roadway Design Challenge
Proposed Hydrograph Mitigated with Bioretention Green Roadway Design Challenge
Proposed Maintenance Requirements <ul><li>Monitor for Johnson grass during initial seeding/sodding growth period immediate...
Proposed Maintenance Requirements <ul><li>Debris and litter pick up on 3-4 week cycles coordinated with roadway sweeping <...
Maintenance Cost Reduction Techniques <ul><li>Use of curbed roadway eliminates need for guardrail repair </li></ul><ul><li...
Maintenance Cost Reduction Techniques <ul><li>Roadway drains toward center median where biofilters; pervious pavers (also ...
Cost Comparison – Low Impact Development versus Traditional Approach <ul><li>Overall construction cost analysis shows that...
Construction Cost Comparison Green Roadway Design Challenge
Preliminary Plans Green Roadway Design Challenge
Preliminary Plans Green Roadway Design Challenge
Preliminary Plans Green Roadway Design Challenge
Preliminary Plans Green Roadway Design Challenge
Preliminary Plans Green Roadway Design Challenge
Preliminary Plans Green Roadway Design Challenge
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GREEN ROADWAY Team 07182 Competition Submittal

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Electronic submittal for team of LJA Engineering and Fugro Consultants

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GREEN ROADWAY Team 07182 Competition Submittal

  1. 1. Low Impact Development Design Competition Green Roadway Design Challenge Houston Land Water Sustainability Forum December 14, 2009 Team No. 07182
  2. 2. Design Objectives <ul><li>Redesign a two lane road with ditches to a four lane thoroughfare in accordance with Harris County Public Infrastructure standards </li></ul><ul><li>Incorporate Low Impact Development design features, reduce impervious cover, promote infiltration, reduce stormwater pollution through bioremediation, and reduce long term maintenance costs </li></ul><ul><li>Develop a corridor that accommodates a shared use path and linear museum concept </li></ul>Green Roadway Design Challenge
  3. 3. Design Assumptions <ul><li>Sample project is Independence Parkway in Harris County Precinct Two from Tidal Road to about 1400 feet south of Park Road 1836 </li></ul><ul><li>Minimum concrete pavement thickness is 10 inches </li></ul><ul><li>Right-of-way is 120 feet </li></ul><ul><li>Due to expansive clay soils and high volume of truck traffic, porous concrete is not suitable for roadway pavement </li></ul>Green Roadway Design Challenge
  4. 4. Low Impact Design Features <ul><li>Curb and gutter section with armored curb inlets to reduce impervious cover (versus shoulders) and add green space </li></ul><ul><li>Reverse crown on road to drain to median and maximize effectiveness of bioremediation features </li></ul><ul><li>Roundabout at south limit of project to eliminate turning conflicts and provide signature starting point for shared use path </li></ul>Green Roadway Design Challenge
  5. 5. Low Impact Design Features <ul><li>Porous concrete pavers for shared use path reduce impervious cover and facilitate infiltration </li></ul><ul><li>Native grasses and composted topsoil to aid in quick establishment of vegetative cover </li></ul><ul><li>Low points in ditches to retain water and promote infiltration </li></ul>Green Roadway Design Challenge
  6. 6. LID Feature: Bio-swale & Bioretention Green Roadway Design Challenge
  7. 7. LID Feature: Pervious Pavers Green Roadway Design Challenge
  8. 8. LID Feature: Pervious Pavers Green Roadway Design Challenge
  9. 9. Typical Pollutant Removal Rates with Bioretention Green Roadway Design Challenge
  10. 10. Estimated Filtration with Proposed Bioretention Green Roadway Design Challenge
  11. 11. LID Feature: Roundabout Green Roadway Design Challenge
  12. 12. Hydraulics and Hydrology <ul><li>Existing Condition = 120 ft ROW with 44 ft of paved surface </li></ul><ul><li>Proposed Condition = 120 ft ROW with 50 ft of paved surface </li></ul><ul><li>Hydrology of Project Area modeled with Rational Method & Small Watershed Method </li></ul><ul><li>Offsite hydrology remains at existing conditions </li></ul>Green Roadway Design Challenge
  13. 13. Hydraulics and Hydrology <ul><li>Proposed Roadway incorporates two right-of-way ditches sized to accommodate offsite flow and a median ditch incorporating bioretention and amenity features </li></ul><ul><li>Proposed Roadway increases impervious surface resulting in increase in peak flow  Q P = 3 cfs and a need to detain 0.39 ac-ft </li></ul><ul><li>Increased flow can be mitigated within median ditch </li></ul>Green Roadway Design Challenge
  14. 14. Existing and Proposed Hydrographs Green Roadway Design Challenge
  15. 15. Proposed Hydrograph Mitigated with Bioretention Green Roadway Design Challenge
  16. 16. Proposed Maintenance Requirements <ul><li>Monitor for Johnson grass during initial seeding/sodding growth period immediately following construction. Eliminate any visible Johnson Grass with herbicide. As native vegetation matures, it will act to prevent Johnson Grass invasion </li></ul><ul><li>Mow parkway center median and 15’ strips on outside of roadway (only) twice a year (Spring and Summer) </li></ul><ul><li>Mow of entire ROW once a year in autumn </li></ul>Green Roadway Design Challenge
  17. 17. Proposed Maintenance Requirements <ul><li>Debris and litter pick up on 3-4 week cycles coordinated with roadway sweeping </li></ul><ul><li>Concrete spall repair/full depth repair on as needed basis </li></ul><ul><li>Curb repair as needed. Fortify curb for large trucks with riprap behind curb as needed </li></ul><ul><li>Replace roadway striping on as needed basis (4” Broken White and 24” Stop Bars only). Curbed roadway eliminates need for solid yellow and solid white striping </li></ul>Green Roadway Design Challenge
  18. 18. Maintenance Cost Reduction Techniques <ul><li>Use of curbed roadway eliminates need for guardrail repair </li></ul><ul><li>Use of curbed roadway reduces pavement needed for shoulders; eliminates need for solid edge striping; eliminates/substantially reduces need for Metal Beam Guard Fence. This provides for less roadway maintenance </li></ul><ul><li>Biofilters and better infiltration reduce velocity of runoff, thus reducing erosion and need for ditch regrading </li></ul>Green Roadway Design Challenge
  19. 19. Maintenance Cost Reduction Techniques <ul><li>Roadway drains toward center median where biofilters; pervious pavers (also acting as a biofilter and allowing for better infiltration) and native vegetation treats stormwater coming off of roadway. Existing roadside ditches will remain to intercept overland flow entering ROW. Reduced velocities means less erosion repair and less re-grading of roadside ditches </li></ul><ul><li>Moving pedestrian features from border area to median area allows for less necessity for mowing of outer border of ROW. This provides for less roadside maintenance </li></ul>Green Roadway Design Challenge
  20. 20. Cost Comparison – Low Impact Development versus Traditional Approach <ul><li>Overall construction cost analysis shows that Traditional design exceeds LID construction costs by nearly 10% </li></ul><ul><li>LID offers cost savings due to reduced area of subgrade stabilization, reduced roadway pavement width, reduced striping requirements and reduced MBGF requirements </li></ul><ul><li>LID requires more excavation due to center median swale, a very slight cost increase for pervious pavers above concrete surface shared use path, and added items such as concrete curb, armor curb drains, and increased planting/vegetation requirements. </li></ul><ul><li>Traditional Approach Construction Cost : $2.948 million </li></ul><ul><li>LID Approach Construction Cost: $2.706 million </li></ul>Green Roadway Design Challenge
  21. 21. Construction Cost Comparison Green Roadway Design Challenge
  22. 22. Preliminary Plans Green Roadway Design Challenge
  23. 23. Preliminary Plans Green Roadway Design Challenge
  24. 24. Preliminary Plans Green Roadway Design Challenge
  25. 25. Preliminary Plans Green Roadway Design Challenge
  26. 26. Preliminary Plans Green Roadway Design Challenge
  27. 27. Preliminary Plans Green Roadway Design Challenge

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