Ramp Signaling Design:Bridge Between Planning and

ImplementationAlex Zhu P.E., PhD., Jillian Scholler P.E.

Objectives Provide all attendees a better understanding of the process from planning to design and implementation.

The major goals include:

Understanding the Ramp Signal System Warrant Analysis

Understanding the Ramp Signal System Design Process

Understanding Ramp Signal System Operations

Outline Introduction

Overview of Ramp Signaling System (RSS) Deployment

RSS in FL

RSS Project Development

RSS Planning

RSS Design

RSS Implementation

RSS Operations

Lessons learned

IntroductionWhat is Ramp Metering Red/Green traffic signals at

freeway on-ramps

Control the rate at which vehicles enter the freeway

Regulate traffic flow

Benefits Reduce Crashes

Break up Platoons

Divert Traffic

Increase Vehicle Throughput

Cost-Effective

Overview of Deployment

Fort Lauderdale

Ramp Signaling in FL CO –RSS Warrant Study (2012); TSM&O Strategic Plan (2013);

RSS Implementation Guide (2017);

D4 - I-95 Managed Lane Phase 3 (54 RS) • Phase 3A (29 RS)– design/construction, Operation 2019• Phase 3B (15 RS)– design, Operation 2023• Phase 3C (10 RS)– Procurement, Operation 2024

D5 - I-4 Managed Lanes (11 RS) - under construction, Operation 2021

D6 - I-95 Managed Lane Phase 1 (22 RS) - Operation since 2009

SR-826 Managed Lanes (19 RS) – construction, Operation 2019

D7 - TBX is evaluating RSS feasibility

FTE – Completed evaluation and future deployment

RSS Project Development

RSS Plan - Warrant Analysis

• The FDOT technical report titled “Integrated Database and Analysis System for the Evaluation of Freeway Corridors for Potential Ramp Signaling” provides an outline for Ramp Metering Warrant Analysis.

• This recommends seven warrants to identify potential locations for ramp metering. Which can be grouped into three general categories:

Traffic Data

(1,2,3,&4)

Roadway Geometry

(5&6)

Crash Data

(7)

RSS Plan – Data Collection

Geometry

• Ramp Storage

• Acceleration Distance

Traffic Data

• ML Volume & Speed

• Ramp Volume Crash Data

• Crash Rate

RSS Plan - Warrant Analysis

• Warrant 1 – Mainline Peak Period Volume > 1200 vphpl.

• Warrant 2 – Mainline Peak Period Speed < 50 mph

• Warrant 3 – Ramp Volume• Single lane Ramp: Peak hour on-ramp volume is 240 to 1,200 vph.

• Multi- lane Ramp: Peak hour onramp volume is 400 to 1,700 vph.

• Warrant 4 – Total Mainline and Ramp Volume• Condition 1: The sum of peak hour mainline volume and ramp volume

exceeds specific threshold values.

• Condition 2: Peak hour volume of the rightmost mainline lane exceeds 2,050 vph.

Warrant Analysis

• Warrant 5 – Ramp Storage is greater than Queue Length

Where,

L = the required single-lane storage distance in feet, and

V = the peak hour ramp demand in vph.

• Warrant 6 – Acceleration Distance is longer than the safe mergingDistance

Where,

L = the required minimum acceleration distance in feet, and

V = the freeway mainline prevailing speed in mph.

Warrant Analysis

• Warrant 7 – Crash Rate of facility of roadway segment is greater than 80 crashes per hundred million vehicle miles (RHMVM

Where,

RHMVM = Crash rate per hundred million vehicle-miles,

AADT = Average Annual Daily Traffic on the facility, and

Length = Length of roadway segment (miles).

RSS Plan - Warrant Analysis

RSS Design - Component

Controller

Signal

Detectors

Cabinet

Flashers

Signing

CCTV

TMC

Power

Communication

RSS Design – Cabinet Cabinet Components

• Controller

• UPS/Battery

• Detector Card

• Load Switch

• Communication (Layer 2 Switch, FOC patch panel)

• Power Panel

• CCTV Device (Media Convertor, decoder, etc.)

Cabinet Design Concerns• Typically dedicated and ground mounted

• Placement - Ensure maintenance accessibility

• Orientation – Ensure view of Signal head, Queue, detector and ramp operations

• Safety – behind Guardrail or Barrier

RSS Design – CCTV

Dedicated per Ramp Signal

HD with PTZ function

100% coverage of entire ramp, signal head, queue and adjacent intersection

Typically sharing cabinet with RSS

Preset views in SunGuide

Avoid obstruction from Landscaping

RSS Design – Signal

Two/Three Section Signal

Located next to Stop bar

Two Signals Per Pole • Top for Coming Vehicles

• Bottom for Stopping Vehicles

Type of Ramp

• One Lane – Type 1 signal pole

• Two Lane - Type 1 pole both sides

• Three Lane- Mast Arm or pole

• With HOV Preferential Lane

RSS Design – Signal

RSS Design – Signal

RSS Design – Signal

RSS Design – Signal

RSS Design – Detectors Freeway Detection

• Upstream detector – MVDS, configurable, existing or new

• Downstream detector – MVDS, configurable, existing or new, depending on bottleneck locations

• Mainline – MVDS, immediate downstream of gore, fed to controller directly

Ramp Detection• Demand – typically loop, presence detection

Dual loops 6’ from Stop Bar

• Passage – typically loop, presence detection Dual loops 8’ from Stop Bar

• Queue loop – typically dual loops, queue detection < 50 ft from intersection, if ramp <1320 ft,

< 1200 ft from signal ,if ramp > 1320 ft

• Intermediate Loop – Optional

• Bridge ramp – MVDS or video, no loop

• Vehicle classification

RSS Design –Warning Signs Flasher Beacon

• Located prior to ramp entrance for each movement

• Accompanied by Sign W3-8

• Flashes when RSS is on - warning

• Divert Traffic

Advanced Sign• W3-4/W 3-7

• Optional

• Located prior to ramp entrance

Advanced warning for signal• W3-3

• Optional

• Located on both side of ramp

RSS Design – Stop Bar and Regulatory Signs

Stop Bar – must be properly located• Meet acceleration length requirement

• Provide adequate storage on ramp

Stop Bar Sign• R10-6x

• Mounted on signal pole

X Vehicles Per Green• R10-28/R10-29

• Flow control strategy determined by ramp volume analysis

• Post mounted adjacent to signal pole

RSS Design – Signs

RSS Design – One Lane Ramp

RSS Design – Two Lane Ramp

RSS Design – Two Lane Merge Ramp

RSS Design – One Lane Loop Ramp

RSS Implementation - Public Outreach

Start Early - End of Feasibility Study

Continue through Operational Start up

Focus Groups • Local Motorists

• Local Elected Officials

• Neighborhood/Community Associations

• Media

Tactics

• Email

• Brochures/Advertisements

• Public Meeting & Mail-outs

• TV/Radio/Newspaper interviews

RSS Implementation - Enforcement

Visible and Consistent Enforcement

Dedicated Resource through Hire-back program

Suggested Opening Coverage Schedule• Weeks 1 - 2 : 100%• Weeks 3 - 4 : 50%• Weeks 5 - 6 – 25%• Week 7 - 52 - Targeted coverage

Frequent meetings with FDOT & FHP throughout first year

RSS Implementation - TMC Readiness

Software development acquisition

Hardware Acquisition

SOG Development

Operations Staff Training

Maintenance Staff Training

Workstation Configuration & Set up

RSS Operation – Operation Mode

Pre-Timed Traffic Responsive

Local • No real-time data is needed• Requires periodic manual update• Appropriate for localized issues• Less effective for non-static conditions

• Vehicle detection is needed• Appropriate for localized issues• Higher capital and maintenance costs

than pre-timed systems• Greater benefits

System-Wide • Appropriate for widespread issues• Vehicle detection is not needed• Rarely used, as compared to system-wide

traffic responsive systems

• Vehicle detection is needed• Appropriate for localized issues• Most useful for corridor, system-wide

applications• Greatest capital and maintenance costs,

but yields most benefits

RSS Operation – Metering Rate Calculation

Rate is calculated as the # of vehicles allowed to enter the freeway every minute. For example: 10 Vehicles per Minute (6 sec cycle length)• Green Time: 1.5 Sec (fixed)• Red Time: Cycle Length - Green Time; Minimum 1 Sec

The algorithm calculates Rate based on real time traffic

Vm - Speed from MainlineOm- Occupancy from MainlineOr - Occupancy from Ramp

Metering Rate Calculated based on one-minute moving average

RSS Operation – SunGuide RSS Module

Manual On/Off

Local Traffic Responsive

Local Time of Day

Uses Fuzzy logic to calculate metering Rates

Compatible with 170 Controllers • 2070 compatibility currently

under development

RSS Operation – D4 Operations Plan Fully Automated Activation/Deactivation Process

Traffic Data Triggered SunGuide Event Creation Triggered

Minimal Operator interaction required Freight Bypass

RSS Operation – D4 Operations Plan Strategic Ramp Grouping

• Ramp Volume and Geometry

• Incident severity

• Time of Day / Day of Week

RSS Operation – D4 Operations Plan Strategic Ramp Grouping

• Ramp Volume and Geometry

• Incident severity

• Time of Day / Day of Week

RSS Operation – D4 Operations Plan Strategic Ramp Grouping

• Ramp Volume and Geometry

• Incident severity

• Time of Day / Day of Week

Lessons Learned Corridor implementation vs. per ramp

Warrant study reflects individual ramp issue – impact design, operation process

Storage/acceleration

Enforcement (learning curve for motorists)

PIO

ConOps readiness

Dedicated CCTV (view)

Conflict with Landscaping

Detector type (presence vs. data collection) and placement (queue)

Design for maintenance concern (cabinet location, accessibility, reduce lane closure)

Technology evolution (controller/software update)

Alex Zhu, PhD, PEITS EngineerHDR3250 W. Commercial Blvd., Suite 100Fort Lauderdale, FL 33309alex.zhu@hdrinc.com

Jillian Scholler, PEManaged Lanes CoordinatorAECOMSMART SunGuide RTMC2300 West Commercial Blvd.Fort Lauderdale, FL 33309JScholler@smartsunguide.com

Questions?