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The State Route 246Central Avenue Ext. and Purisima Road
Traffic Study
May 2008
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Objective of the StudyTo examine the 2030 traffic impacts associated with four roadway improvement alternatives to access the City of Lompoc from Route 246 and to evaluate the critical intersection LOS within in the study area.
Interagency Steering Committee: City of Lompoc, County of Santa Barbara, Caltrans, SBCAG
The Four AlternativesAlt 1 – 2030 No-Build (Programmed Forecast)
Alt 2 – 2030 Central Ave Ext. as a 2-Lane Minor Arterial
Alt 3 – 2030 Central Ave Ext. as a 4-Lane Minor Arterial
Alt 4 – Widen Rt. 246 e/o Rt. 1 to a 4-Lane Minor Arterial
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Socioeconomic Forecast for the Study Area
Lompoc & Unincorp Areas 2000 2030 % Incr.Population 46,347 62,846 35.6%Households 14,876 18,918 27.2%Employment 12,030 16,518 37.3%
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(03) 8900, PH = 9.2%
(03) 11540, PH = 8.5% (06) 11100. PH = 9.0%
(03) 9200, PH = 12.6% (06) 8600, PH = 9.9 %
(03) 33740, PH = 6.8% (06) 31480, PH = 8.2%
(03) 16240, PH = 8.6% (04) 13800, PH = 8.3%
Daily & PMPH Traffic
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8900, Trucks = 4%
11540, Trucks = 4%
9200, Truck = 11%
33740, Trucks = 5.6%
16240, Truck = 6.3%
Traffic and Truck %
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Distribution by Truck Type - PM Peak HourCentral Ave e/o H Street - Eastbound
0
5
10
15
20
25
2-4 Axle Unit Truck Semis Tractor-Trailers
Num
ber o
f Tru
cks
File : H:\NewMo del\246Study/Centra l Ave Tk Tx 2002
2002 Traffic Distribution - PM Peak Hour Central Ave e/o H Street - Eastbound
2.0%
68.0
%
23.5
%
0.3% 6.
2%
0%
20%
40%
60%
80%
100%
Motorcyles&Bikes
Auto P.Up Buses Trucks
Truck Traffic
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Four Study Alternatives
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Traffic Impacts: Alt. 1 vs. Alt. 2
Traffic Impacts on City's Arterials Alt. 1 vs. Alt. 2
-
5,000
10,000
15,000
20,000
25,000
30,000
Alt 1 (No Project) Alt 2 (Central Ext. 2-Ln)
Central e/o O St North w/o H St H St n/o College
Impacts on Central Ave Ext'nAlt. 1 vs. Alt 2
-
5,000
10,000
15,000
20,000
25,000
Alt 1 (No-Build) Alt 2 (Central Ext. 2-Ln)
Central Ext'n w/o Rucker Ocean e/o 7St SR246 e/o Rt1
Traffic Impacts on Central Ext., Rt. 1 & Ocean Alt. 1 vs. Alt. 2
-
10,000
20,000
30,000
40,000
50,000
Alt 1 (No-Build) Alt 2 (Central Ext. 2-Ln)
Central e/o H St Rt. 1 n/o Central Ocean e/o H St
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Critical Intersection LOS Analysis
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• Focus on P.M. Peak Hour• Forecast
– Growth factors from SBCAG model– Applied to current turning movement count data
• Level of Service (LOS)– Grades A (free-flow conditions) through F (heavy
congestion)– Intersection Capacity Utilization (ICU) Methodology
• Some capacity improvements were assumed to be in place for the Year 2030 scenario
Critical Intersection LOS Analysis
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Intersection Improvements Assumed for Analysis
1. Purisima Rd/H St-Rte. 1 One SB through lane added south of intersection *
2. Purisima Rd/Rte 246 Traffic signal*
3. Central Ave/H St Add one left-turn lane on NB and SB approaches*
* Source: Wye Specific Plan EIR
1
23
YEAR 2030 P.M. PEAK HOUR INTERSECTION LOSALTERNATIVE 1
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YEAR 2030 P.M. PEAK HOUR INTERSECTION LOSALTERNATIVES 2 & 3
Intersection Improvements Assumed for Analysis
1. Purisima Rd/H St-Rte. 1 One SB through lane added south of intersection *
2. Purisima Rd/Rte 246 Traffic signal*
3. Central Ave/H St Add one left-turn lane on NB and SB approaches*
4. A St/Central Ave Traffic signalWiden NB and EB approaches
5. Central Ave/Rte 246 Traffic signal
* Source: Wye Specific Plan EIR
1
32
45
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Intersection Improvements Assumed for Analysis
1. Purisima Rd/H St-Rte. 1 One SB through lane added south of intersection *
2. Purisima Rd/Rte 246 Traffic signal*
3. Central Ave/H St Add one left-turn lane on NB and SB approaches*
* Source: Wye Specific Plan EIR
YEAR 2030 P.M. PEAK HOUR INTERSECTION LOSALTERNATIVE 4
1
2
3
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Conclusions• Alt. 2 provides a direct access from Rt.246 to the City of
Lompoc. The Central Ave Ext. has a significant impact in terms of:– Diverting approx. 8,100 ADT (46%) traffic volumes from Rt.246– Providing a primary truck access from Rt. 246 to the City and nearby
communities– Facilitating an alternate route for traffic between Downtown and Mesa
Oaks/Mission Hills– Increasing PM peak volumes on Central Avenue by approx. 15-30%
• Alt. 3 offers no significant benefits with the added capacity on the Central Ave Extension.
• Alt. 4 does not appear to provide any operational benefits.• With adequate capacity improvements in place, most study area
intersections would operate efficiently with Central Avenue Extension except the Central Avenue and H Street intersection.
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• Interagency MOU between County, City of Lompoc, and SBCAG for continued study of improvement alternatives. Cost sharing among County and City with SBCAG as Project Manager
• RFP for Feasibility Study to examine costs (e.g. bridge, road improvements), environmental issues (e.g. sensitive habitats), etc. of improvement alternatives
• Feasibility Study subject to public review
Next Steps: