1 Clement Avenue/Tilden Way
Project
City Council
March 7, 2023
2 Introduction
Clement Avenue
Extension Alternatives at
Tilden Way
Project Team:
• City of Alameda
• Kittelson & Associates, Inc
• Stakeholder Participants:
City, AC Transit, Alameda Housing Authority, BART, Bike Walk Alameda, County, DABA, Edison School, Bay Trail, BCDC, Bridgeside Shopping Center, City of Oakland, Commission on Persons with Disabilities, Greer Mortuary, Transportation Commission, Unity Council in Oakland, Members of the Public
Engagement and Outreach Update:
• Letter to adjacent properties
• Outreach via social media, emails and sandwich boards • Website: www.alamedaca.gov/ClementTilden
3 Purpose
Project Goals and Intended Outcomes
Prioritize safety
Improve mobility for all roadway users
Improve bicycle and pedestrian access
Provide flood reduction and
landscaping opportunities
Reduce greenhouse gas emissions
Comply with City plans and policies
4 Background
• Measure BB grant for $10
million
• Union Pacific property
acquisition
• Environmental clean-up
• Fill gap in active
transportation and truck
network
5 Project Timeline
2016
Early 2022
Brainstorming Initial Ideas
Gather and compile
stakeholder input
Spring 2022
Existing Conditions Analysis
Existing conditions and
project outcomes
2024
Construction
Begin construction of
preferred alternative
Project webpage:
www.alamedaca.gov/ClementTilden Late 2022/
Early 2023
Project Development
Identify and refine preferred
alternative
2023
Final Design
Begin final design for
preferred alternative
6 Desires:
• Safety and slower speeds
• Connectivity for bicyclists
• Safer pedestrian crossings
• More greenery, open space and dog park
Concerns:
• Through traffic and speeding on Clement Ave.
• Increase of truck traffic with extension
• Drivers’ unfamiliarity with roundabouts
• Speeding along Pearl St and Fernside Blvd
Public Input
(2 rounds of outreach)
Virtual Workshop
• 6/18/22: 31 attendees; 21 responses
• 10/11/22: 32 attendees; 14 responses
In-Person Open Houses
• 6/19/22: 19 attendees
• 10/12/22: 15 attendees
Online Surveys
• 6/19/22: 175 respondents
• 10/2022: 116 respondents
7 Safety
Reported Injury Collisions 2011-2020
• High injury corridor and high crash
intersection (21 reported injury crashes)
• Pedestrians and bicyclists account for 38%
of total injury crashes but only 9% of study
area trips
• Park Street (not pictured) is a Tier 1 high
injury corridor
High-injury Corridor
High-injury Intersection
High Injury Corridor
High Crash Intersection
8 Traffic Operations
• Adjusted 2022 traffic counts to
approximate pre-COVID levels
• All study intersections operate at or
below 75% of their capacity during the
weekday AM and PM peak hour
9 Study Area: Cross Alameda Trail
10 Study Area AC Transit Bus Service
11 Truck Connections
Designated Truck Routes
• Alameda: Park St. Bridge and Miller-Sweeney Bridge
• Oakland: Park St. Bridge, Miller-Sweeney Bridge, and
High St. Bridge
Truck Route
Freeway
Truck Route
Truck Usage
• Trucks east of Broadway are funneled to Miller-Sweeney Bridge • Trucks west of Broadway use Park Street (heavy truck usage on Park St)
Park Street
Bridge
Miller
Sweeney
Bridge
High Street
Bridge
Note: Sharp right turn from Tilden to
Broadway is on designated truck route.
12 Truck Volumes
Truck Travel Patterns
• 4-5x the truck activity on
Park Street Bridge compared
to Miller-Sweeney Bridge
• Broadway and Park are
main N-S corridors
• Central and Otis are primary
E-W corridors
Source: Caltrans Northern Alameda County Truck Access Study
13 Draft Concept
Tilden/Blanding/Fernside Intersection
14 Draft Concept
Broadway/Tilden Intersection
15 Overall
Evaluation
Project Intended Outcome Benefits
• Safety
• Improvements for all modes at roundabout and Broadway/Tilden • Reduce speeds
• Adding sidewalks and crossings
• Restricting high-conflict movements
• Reduced volume at Broadway/Blanding
• Reduces truck volumes along Park Street (High Injury corridor) • Trucks connecting to Clement extension do not cross over CAT • Improve mobility for all roadway users
• Improve bicycle and pedestrian access
• Reduce greenhouse gas emissions
• Improved biking/walking connections
• Improved bus access
• Direct truck and motor vehicle access to Clement
• Improved walking and biking conditions encourages mode shift • Flood Reduction/Landscaping • New stormwater gardens and bioretention areas • Comply with City plans and policies • Completes General Plan truck network • Extends Cross Alameda Trail
16 Next Steps
o 2023: Design
o 2024: Construction
o 2025: Complete
o Project webpage:
www.alamedaca.gov/ClementTilden
Gail Payne
Senior Transportation Coordinator
[email protected] or 510-747-6892
17 17s (15s)
16s (11s)
35s (37s)
11s (12s)
39s (29s)
16s (11s) Average Travel Time Delays
Without Project (With Project)
s = seconds of average delay
2022 Volumes with COVID adjustment
Existing / Project Delay Comparison
18 Anticipated queue lengths,
Weekday PM Peak Hour
19 Anticipated queue lengths,
Weekday PM Peak Hour
20 Emergency/Evacuation
Scenarios
Managed Scenario
• Can run the roundabout eastbound only (“contraflow”)
• Can use one of the two multi-use paths for emergency
vehicles
• Maintains two lanes outbound
• Lose capacity for 1/3 mile to Fruitvale Avenue in
Oakland
Fruitvale Avenue
drops to 1 lane here
Alameda
Avenue doesn’t
provide major
connections
Unmanaged scenario
• Lose some capacity (2 lanes to 1) for about
1/3 mile
• Fruitvale Avenue in Oakland becomes
bottleneck (2 lanes to 1)
Conceptual Managed Scenario
21 Lane Reduction
Reduce number of travel lanes (commonly
called “Road Diet”)
• Lower speeds
• 19 – 47% crash reduction (right-angle, turning,
rear end crashes)
• Shorter pedestrian crossings
Source: FHWA
22 Design Details
Raised Crosswalks
• Design can be adapted to roundabouts
• Compatible with large vehicles
• Research and design guidance informs the
design
23 Safety Performance
Safety Statistics
• 90-100% reduction in fatalities
• 75% reduction in injuries
• 35% reduction in total crashes
• Lack of pedestrian and bicyclist crash
frequency
• Reduction in conflict number and
speeds
Merging
Diverging
Crossing
Source: NCHRP Report 572, NCHRP Report 672
Roundabouts reduce conflict point number and severity
24 Roundabouts and Pedestrians
•Benefits:
• Slow vehicle speeds
• Two-stage crossing
• Considerations:
• Crosswalk alignment
• Width of splitter island
• Space for exiting vehicles to yield
to pedestrians
• Yield-controlled crossings
Storage space
for exiting
vehicles
Median refuge
and two-stage
crossing
Sources: Google Earth; Kittelson
25 Why Build Roundabouts?
Roundabout benefits include:
• Safety performance
• Lower delay
• Environmental benefits (emissions, fuel savings)
• Access management
• Operations and maintenance costs
• Aesthetics
26 Vehicle Speeds: Reduced
•Geometry controls speeds
–Max entry speed:
•25 mph for single-lane
•30 mph for two-lane
–Circulating speeds 10 to 12mph
•Increased time for driver reaction
•Decreased chance for injury or
fatality
27 Roundabouts and Accessibility
Considerations for Visually Impaired:
1. Well defined walkway edges
2. Separated walkways
3. Aligned detectable warnings
4. Perpendicular crossings
5. Contrasting crosswalk markings
Performance assessment detailed in NCHRP Report 834
4 3
5 2
1 28
Separate Bike/Ped Options
San Luis Obispo, California
Source: Brian Ray
Source: Massachusetts DOT Separated Bike Lane Planning and Design Guide 29 Roundabouts and Large Vehicles
• “Design” versus “accommodate”
larger vehicles
• Accommodations include:
• Truck aprons
• Placement of landscaping
• Reinforced curbs
30 Reduced Travel Delay
• May solve existing or projected
operational problem
• Heavy delay on minor road
• Large traffic signal delays
• Heavy left-turning traffic
• Stop control with large delays
Source: NCHRP Report 672, NCHRP Exhibit 3-19
Comparative Delay, Signal versus Roundabout
Intersection that meets Signal Warrants
31 Truck Volumes
Miller-Sweeney Bridge 2022 Truck
Volumes
• Trucks account for 2 - 5% of daily traffic on
Fruitvale Avenue to/from Oakland
• Balanced truck volumes to/from Oakland
all day
• Higher truck volumes on Blanding than
Clement
• The project should continue to provide truck
access to/from Nob Hill shopping center.
• Trips to Oakland appear to be served better
by Park Street Bridge
All-day Counts, Trucks with Trailers (December 2022)
32 Miller- Sweeney Bridge
Bridge Events
• Average 34 times a month (1-2 times/day)
• Typical 5-10 minute event (depends on vessel)
• Typically avoid AM and PM peak hours
• Similar to a rail crossing
Vehicle queues during bridge
events (2022)
Example Roundabout near rail
crossing in Kennewick, Washington
33 Dealing with future volumes
Managed Scenario
• The roundabout shows to be below capacity
even with conservative adjustments.
• If future volumes grow, a roundabout can be
metered to manage delays and queues.
• Example shown from Columbia Park Trail,
Richland, Washington