sw 8 th avenue at sw 91 st street intersection modification
DESCRIPTION
SW 8 th Avenue at SW 91 st Street Intersection Modification. Board of County Commissioners November 8, 2011. Outline. Recommendation Project Background and Location Traffic Analysis Comparison of Alternatives Public Meeting Recommendation. Recommendation. - PowerPoint PPT PresentationTRANSCRIPT
SW 8th Avenue atSW 91st StreetIntersection Modification
Board of County CommissionersNovember 8, 2011
Outline
RecommendationProject Background and LocationTraffic AnalysisComparison of AlternativesPublic MeetingRecommendation
Recommendation
Direct staff to proceed with the design of a signal with left turn lanes at the intersection of SW 8th Avenue at SW 91st Street and proceed with the bid phase when design is complete
Project Background2005 Tower Road Network Study
Examined intersection capacities on Tower Road and surrounding networkAnalysis based on Comprehensive Plan Policy 1.1.4 which adopts LOS D for motor vehicles as the minimum standard for collector and arterial roadsRecommended intersection modifications on Tower Road and at six other locations on the networkSW 8th Avenue at SW 91st Street included in the six network modifications
Design and construction funded with $500,000 of Impact Fees
Project Background
Alachua County Mobility PlanAdopted in April 2011Places emphasis on an interconnected roadway networkExtends SW 8th Avenue to SW 143rd Street and to SW 20th Avenue to serve as an east-west alternative to Newberry Road
8th Avenue Extension
8th Avenue Connector
8th Avenue and 91st Street Intersection ImprovementsI-75 Overpass Widening
Tower Road From Archer Road to 8th Avenue
SW 8th Avenue
SW 91
st Street
Project Location
Scenic Road Protection Area
Volume
Speeds
ClassificationPosted 85th
Percentile
SW 8th Avenue 5,690 40-45 mph 39 mph Major Collector
SW 91st Street 8,000 30 mph 40 mph Major Collector
Traffic Data
Crash Data (2004-2009)No. Type Fatal Injury Contributing Cause
1 Angle 0 0 Failure to Yield Right-of-Way
2 Left Turn 0 0 Disregard Stop Sign
3 Left Turn 0 0 Failure to Yield Right-of-Way
4 Angle 0 0 Failure to Yield Right-of-Way
5 Ditch 0 1 Brake Failure
6 Angle 0 0 Failure to Yield Right-of-Way
7 Angle 0 0 Failure to Yield Right-of-Way
8 Angle 0 0 Failure to Yield Right-of-Way
9 Ditch 0 0 Disregard Stop Sign
10 Angle 0 0 Failure to Yield Right-of-Way
11 Angle 0 0 Failure to Yield Right-of-Way
12 Rear End 0 0 Careless Driving
13 Angle 0 0 Failure to Yield Right-of-Way
14 Rear End 0 0 Careless Driving
15 Angle 0 0 Failure to Yield Right-of-Way
16 Angle 0 0 Disregarded Stop Sign
17 Sideswipe 0 0 Careless Driving
Signal Warrant AnalysisWarrant Applicable Satisfied Comments
1A Minimum Vehicular Volume Yes Yes-100%The required volumes were met at the 70% level during
the peak hour. The 70% level was used because the 85th-percentile speed is 41 mph.
1B Interruption of Continuous Traffic Yes No The required traffic volumes were met for seven out of
the eight required hours.
2 Four Hour Vehicular Volume Yes YesThe required traffic volumes were met for all four hours at the 70% level. The 70% level was used because the
85th-percentile speed is 41 mph
3A Peak Hour Delay No No This warrant is not applicable because there is not a special condition to warrant its use.
3B Peak Hour Volume No YesThe required volumes were met at the 100% level but
this warrant is not applicable because there is not a special condition to warrant its use.
4 Pedestrian Volume No No Only four pedestrians were observed crossing the intersection during the time period studied.
5 School Crossing No No There is not a school located within walking distance of this intersection.
6 Coordinated Signal System Yes NoThe two closest signals are almost a mile away. This
would reduce the effectiveness of the signals to platoon the traffic
7 Crash Experience Yes No There were not enough correctable crashes at this intersection in 2009.
8 Roadway Network Yes Yes Both roads are major routes.
Roundabout JustificationBased on Florida Department of Transportation Roundabout GuideEvaluates intersection in seven categories
Community enhancementTraffic calmingSafety improvementAll-way stop control alternativeLow volume signal alternativeMedium volume signal alternativeSpecial conditions
Roundabout Justification
Evaluation of contraindications (emergency response, right-of-way, etc.)Results of roundabout justification
Roundabout justified as safety improvement, AWSC alternative and low volume signal alternativeDetermined two possible contraindications
Emergency response routeLimited right-of-way
All contraindicating factors can be mitigated
Comparison of AlternativesCompared five alternatives
Existing stop controlTraffic signal with left turn lanes
Signal Layout
Comparison of AlternativesCompared five alternatives
Existing stop controlTraffic signal with left turn lanesSingle lane roundabout with full right turn slip lane
Roundabout 1 Layout
Comparison of AlternativesCompared five alternatives
Existing stop controlTraffic signal with left turn lanesSingle lane roundabout with full right turn slip laneSingle lane roundabout with modified slip lane
Roundabout 2 Layout
Comparison of AlternativesCompared five alternatives
Existing stop controlTraffic signal with left turn lanesSingle lane roundabout with full right turn slip laneSingle lane roundabout with modified slip laneSingle lane roundabout without slip lane
Roundabout 3 Layout
Comparison of AlternativesCompared five alternatives
Existing stop controlTraffic signal with left turn lanesSingle lane roundabout with full right turn slip laneSingle lane roundabout with modified slip laneSingle lane roundabout without slip lane
Compared alternatives in four areasOperational efficiencyEnvironmental impactsSafetyCosts
Operational Impacts
Performed capacity analysis based on Comprehensive Plan Policy 1.1.4
Based on Highway Capacity Manual methodolgiesAnalyzed all options during the AM and PM peak hours in the current year and design year
Reviewed anticipated capacity of SW 24th Avenue at 91st Street roundabout vs. actual
Operational Analysis
Current Year (2010) Design Year (2033)
AM Peak PM Peak AM Peak PM Peak
OverallLOS
OverallAverage
Delay(s)
OverallAverage
Delay(s)
OverallAverage
Delay(s)
OverallAverage
Delay(s)
OverallAverage
Delay(s)
Overall LOS
OverallAverage
Delay(s)
AWSC F 61.1 C 24.2 F 459.4 F 347.2
Signal A 8.2 A 7.4 B 19.1 B 10.3
Roundabout 1 A 6.7 A 7.1 C 25.0 B 14.5
Roundabout 2 A 6.8 A 7.1 C 25.3 B 14.6
Roundabout 3 B 10.0 A 8.6 E 79.9 C 24.4
SW 24th Avenue at SW 91st Street
Year
PM Peak
OverallLOS
Overall Delay Volume
Original Study 2005 A 2.3 1494HNTB Study 2005 B 15.0 1325
Environmental Impacts
Evaluated three areas of environmental impactsPotential tree impactsStormwater runoffGasoline consumption
Tree Impacts - Signal
Tree Impacts – Roundabout 1
Tree Impacts – Roundabout 2
Tree Impacts – Roundabout 3
Tree Impact Summary
IntersectionType
Number of Trees Impacted
AWSC 0
Signal 0Roundabout 1 50-60Roundabout 2 40-50Roundabout 3 40-50
Stormwater - SignalStormwater Impacts – Signal
Stormwater Impacts – Roundabout 1
Stormwater Impacts – Roundabout 2
Stormwater Impacts – Roundabout 3
Stormwater Summary
IntersectionType
Increase in Impervious Area
(Square Feet)AWSC 0Signal 15,500
Roundabout 1 19,800Roundabout 2 13,500Roundabout 3 10,500
Gasoline Consumption
IntersectionType
Gasoline Consumption (gallons)
2010 2033
AM PM AM PM
AWSC 68.0 49.0 319.0 148.0Signal 47.0 39.0 75.0 65.0
Roundabout 1 23.9 24.8 53.4 42.3Roundabout 2 23.9 24.8 53.5 42.3Roundabout 3 30.1 25.3 69.6 45.4
SafetySafety benefits of signals
Potential to reduce head-on, angle and left turn crashesPositive direction to motorists, bicyclists and pedestriansAlerts visually-impaired pedestrians
Safety benefits of roundaboutsLower speeds through intersectionProvides pedestrian refugeReduces conflict pointsSafety benefits decrease as more lanes are added
Comparison of Intersections
IntersectionCrashes Rates (2004-2009)
Total Rate Injury Rate
SW 91st at SW 24th .66 .04
SW 75th at SW 24th 1.23 .27
SW 91st at SW 8th .47 .03
CR 241 at NW 39th .39 .20
Costs
Evaluated total life-cycle costs taking into account:
Right-of-way acquisitionDesignConstructionOperation and maintenance
Right-of-Way - Signal
Existing Right-of-way
Right-of-Way – Roundabout 1
Existing Right-of-way
Proposed Right-of-way
Right- of Way – Roundabout 2
Existing Right-of-way
Proposed Right-of-way
Right-of-Way – Roundabout 3
Existing Right-of-way
Proposed Right-of-way
Right-of-way Needs Summary
IntersectionType
Additional Right-of-way Needed
(Acres)AWSC 0Signal 0
Roundabout 1 .50Roundabout 2 .33Roundabout 3 .25
Operation and Maintenance SummaryIntersection
Type Electric Maintenance Annual Total
Annual Growth
Rate20-year Life
AWSC $ 650 $ 400 $1,050
2%
$26,000Signal $ 650 $ 4,850 $ 5,500 $ 134,000
Roundabout 1 $2,700 $1,500 $ 4,200 $ 102,000Roundabout 2 $2,700 $1,500 $ 4,200 $ 102,000Roundabout 3 $2,700 $1,500 $ 4,200 $102,000
Total Life-Cycle Costs
AWSC Signal Roundabout 1 Roundabout 2 Roundabout 3
Right-of-Way $ - $ - $ 123,000 $ 87,000 $ 78,000
Construction $ - $ 462,000* $ 614,000 $ 435,000 $ 390,000
Design $ - $ 69,000 $ 92,000 $ 65,000 $ 59,000
O&M $ 26,000 $ 134,000 $ 102,000 $ 102,000 $ 102,000
Total Costs $ 26,000 $ 665,000 $ 931,000 $ 689,000 $ 659,000
* Assumes steel mast arm construction
Comparison of AlternativesOperations Safety Environment Costs
AWSC
Signal
Roundabout 1
Roundabout 2
Roundabout 3
Public MeetingHeld on August 18, 2011Noticed through e-mail, mailouts, press releaseOver 60 people in attendanceReceived written comments from 26 individualsPrimary concerns included
Preserving scenic quality of 91st StreetIncreased runoffCostsRight-of-way aquisitionSplit preference between keeping AWSC and roundabout
Recommendation
Direct staff to proceed with the design of a signal with left turn lanes at the intersection of SW 8th Avenue at SW 91st Street and proceed with the bid phase when design is complete
Questions ?