2007 TRB Planning Application Conference D ELDOT S TATEWIDE E VACUATION M ODEL.

2007 TRB Planning Application Conference

DELDOT STATEWIDE EVACUATION MODELDELDOT STATEWIDE EVACUATION MODEL

BACKGROUNDBACKGROUND

In 2006 the Delaware Department of Transportation began updating hurricane evacuation plans for Sussex, Kent, and New Castle Counties. They wanted to develop estimates for the durations of evacuations within each of these counties.

Need for Evacuation Planning

Delaware is located on the Delmarva Peninsula, situated between the Atlantic Ocean, Delaware Bay, and Chesapeake Bay

Their prime beach areas are located about 2 ½ hours from Washington, D.C. and Baltimore, MD



Two of the primary routes on and off of the Peninsula are bridges susceptible to congestion and closure during storm events.


Photo by Scott Kozel



Fortunately, Delaware does not have much history of large-scale evacuations and not much documentation of how long it would take to evacuate.

BackgroundBackground

Today we will use a Sussex County evacuation as a case study.

Maryland

Virginia

New Jersey

Pennsylvania

Delaw

are Bay

Chesapeake B

ay

Virginia

Lewes

Rehoboth Beach

Fenwick Island

Bethany Beach

Ocean City

0 6 12 18 243Miles

Legend

Tourist Area

Study Area

BACKGROUNDBACKGROUNDNeed for Evacuation Planning

Over 50% of the Sussex County Summer Population are not full-time residents

Sussex County has no multi-lane east-westroadways and nolimited-accesshighways

BACKGROUNDBACKGROUNDThe Delaware Department of Transportation set out to develop a model that would estimate the evacuation durations of different “what would happen if…” scenarios based on:

Behavioral Assumptions

Policy Decisions

Operational Assumptions

BACKGROUND – Behavioral Assumptions


At what pace do people evacuate?

How many people evacuate?

Where would people evacuate to?



At what pace to people evacuate?



How many people evacuate?A 2003 report by the US Army Corps of Engineers estimates that:

Between 45% and 80% of full-time residents would evacuate if ordered to

Between 90% and 95% of vacationers would evacuate if ordered to

Between 65% and 70% of the vehicles available to Evacuating Households would evacuate



Where do they evacuate to?

Full-Time Residents 20% stay in their neighborhood

25% would evacuate within Sussex County

25% would stay on the Delmarva Peninsula

30% would evacuate off the Delmarva Peninsula

Vacationers 90% would return home



Where do they evacuate to?

35% to Northern Delaware

22% to Western Sussex County

15% to Bay Bridge

11% to I-95 West

9% to I-95 East


Policy Decisions

When should the evacuation be declared?

Should a “State of Emergency” be declared?

BACKGROUNDBACKGROUNDOperational AssumptionsOperational Assumptions

Should the operational plan be implemented?

CHOOSING A MODELCHOOSING A MODEL

Traditional Approaches

Spreadsheets

Regional Travel Demand Models

Simulation Models

CHOOSING A MODELCHOOSING A MODELSpreadsheets

Benefits:

• Easily explainable

• Relatively easy to implement

Drawbacks:

• Difficult to implement at a large scale

• Difficult to account for specific operations plans

• Difficult to estimate where evacuators go

• Difficult to account for background congestion

CHOOSING A MODELCHOOSING A MODELRegional Travel Demand Model

Benefits:

• Readily available framework from DelDOT’s Statewide Model

• Easy to implement statewide

• Easy to account for background congestion

Drawbacks:

• Difficult to account for spillover

• Difficult to account for specific operations plans

Simulation Model

Benefits:

• Easy to account for specific operations plans

• Easy to account for spillover

Drawbacks:

• Difficult to implement statewide

• Intensive calibration process

• Must estimate trip table externally

CHOOSING A MODELCHOOSING A MODEL

MODEL DEVELOPMENTMODEL DEVELOPMENT

DelDOT chose to use their Statewide Travel Demand Model because of its geographic coverage and ease of implementation.

MarylandNew Jersey

Pennsylvania

Virginia

Delaware

Maryland

Wilmington

Dover

Milford

Lewes

RehobothBeach

BethanyBeach

Atl

anti

c O

cean

Delaw

are Bay

Chesapeake B

ay

Bay Bridge

FenwickIsland

Ocean City

Virginia

/

0 6 12 18 243Miles

Legend

Delaware TAZ

Maryland TAZ

Model Network

Municipality

DelDOT’s Peninsula Model

AADT and peak tourist season assignments

Encompasses Delaware + Maryland’s Eastern Shore (9 Counties)

Covers a population of 1,209,944

Area of 5,375 miles2


Evacuation Model

Capacity constrained model with hourly traffic assignments.

Accounts for the specific traffic control in place at intersections (signals, stop signs, roundabouts).


Evacuation Model 10 groups of “evacuation zones” and

“destination zones” can be specified. Specify evacuation start time Model road closures during evacuation Track spillover between hours Input the pace of evacuation Input the percentage of vehicles

evacuated Specify a “State of Emergency” for

groups of zones


Evacuation Model

Trip Generation

Background Assignment

Evacuation Trip Distribution

Evacuation Trip Assignment


Trip Generation

Uses peak tourist season trip table from Peninsula Model

Determines background trip tables for 96 hours

Determines the number of vehicles in evacuating households (full-time and part-time)

Determines how many vehicles evacuate based on an input assumption (approximately 70% based on US Army Corps of Engineers)


Background Traffic Assignment

Assigns non-evacuation trips to the network for 96 hours from the start of the evacuation.

Accounts for “State of Emergency” assumption.


Evacuation Trip Distribution

Uses specified departure curves and specified evacuation and destination areas.

Uses doubly constrained logit distribution model to determine hourly evacuation trip tables for 30 hours of evacuation.


MODEL DEVELOPMENT – Evacuation Assignment


Assign hourly evacuation trip tables to loaded hourly background traffic networks.

Check for Capacity Constraint.

Spill over-capacity trips to subsequent hours.



Excess Trips spillover to next hour Excess Trips spillover to next

hour

Assign Subsequent Hour Background trips to spillover

network

Assign Subsequent Hour Background trips to spillover

network

Determine Operating Capacity (Jam Density)

Assign Hour 1 Evac. Trips

Check roads where volume exceeds Capacity

Assign Hour 2 Evac. Trips to Spillover Network

Determine Operating Capacity (Jam Density)

Check roads where volume exceeds Capacity

Case Study 1 ParametersCase Study 1 Parameters 50% of non-evacuation traffic in Sussex

County stays home 70% of vehicles in Sussex County Beaches

evacuate Fast evacuation (all evacuees depart within

13 hours) Operational Plan is Implemented Evacuation is ordered at 6:00 AM 8% of evacuees depart prior to the order,

beginning at midnight

Case Study 2 ParametersCase Study 2 ParametersSame as Case Study 1 except with Ocean City, MD evacuation

Case Study ResultsCase Study Results

US 113 North of Georgetown

SR 26 East of Dagsboro

Order at 6:00 AM (2% Evacuating)

Evacuation Trips Exceed Capacity at 11:00 AM (12% Evacuating)

Majority of Evacuation Complete 4:00 PM (10% Evacuating)

Evacuation Complete 7:00 PM

Case Study 1 US 113 Northbound – North of Georgetown


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Background Traffic

Spill-over evacuation tripsfrom previous hours

Evacuation trips gettingthrough during this hour




Evacuation Trips Exceed Capacity at 6:00 AM (2% Evacuating)



Case Study 1 SR 26 Westbound – East of DagsboroCase Study 1 SR 26 Westbound – East of Dagsboro


Evacuation Trips Exceed Capacity

at Noon (12% Evacuating)



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Tri

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Background Traffic

Spill-over evacuationtrips from previoushoursEvacuation trips gettingthrough during this hour

Case Study 2 SR 26 Westbound – East of DagsboroCase Study 2 SR 26 Westbound – East of Dagsboro


Evacuation Trips Exceed Capacity at 8:00 AM (5%

Evacuating)



Case Study 1 Evacuation Volumes by Time of DayCase Study 1 Evacuation Volumes by Time of Day Evacuation at 2:00 am (1%) Evacuation at 8:00 am (5%)

Case Study 2 Evacuation Volumes by Time of DayCase Study 2 Evacuation Volumes by Time of Day Evacuation at 2:00 am (1%) Evacuation at 8:00 am (5%)

Case Study 1 Evacuation Volumes by Time of DayCase Study 1 Evacuation Volumes by Time of Day Evacuation at Noon (12%) Evacuation at 5:00 pm (2%)

Case Study 2 Evacuation Volumes by Time of DayCase Study 2 Evacuation Volumes by Time of Day Evacuation at Noon (12%) Evacuation at 5:00 pm (2%)

Case Study ResultsCase Study Results

Case Study 1 Evacuation duration is 14

hours

Case Study 2 Evacuation duration is 21

hours

ConclusionsConclusions

The model would be easily applied to any situation where capacity constrained traffic assignments would be beneficial (ex. Event Planning, Major Roadway Construction)

The model would be easily modified to estimate non-hurricane evacuations

Next StepsNext Steps

Continue Working with DelDOT to Refine Evacuation Scenarios

Test Road and Bridge Closures Due to Storm Events

Continue to Improve Reporting Capabilities

Questions?Questions?

Scott Thompson-Graves, PE, [email protected]

Laura Rice, [email protected]

Mike [email protected]

2007 TRB Planning Application Conference D ELDOT S TATEWIDE E VACUATION M ODEL.

Documents

Transcript of 2007 TRB Planning Application Conference D ELDOT S TATEWIDE E VACUATION M ODEL.