Work Zone
Impacts
Module 5
What is a WZ Impact Assessment?
WZ Impact Assessment is the process of
understanding the safety and mobility
impacts of a road construction or
maintenance project
Basic Concept

Determine impacts of project?
 Acceptable?
If yes, no problem
 Unacceptable? (Significant project)

Can strategy be found to mitigate impacts to
acceptable level?
Yes – develop TMP
 No – determine best strategy
 Advise stakeholders of possible problems

WZ Impacts Considerations

Maximizing Safety
 Road
Users
 Workers

Maximizing mobility and accessibility
 Road
user costs
 Emergency services
 Businesses

Constructability
 Building
projects effectively and efficiently
Benefits of Assessing Impacts




Identify and understand all impacts of the project
Identify “significant projects” and determine
suitable TMP
Aid in identifying and evaluating alternative
strategies
Monitor and manage WZ impacts during
construction
Mobility Impacts

Mobility Issues
 Delay
Reduced quality of life issues
 Significant Projects – agency definition
 Reduced Speeds
 Queues and complete stoppages

 Freight
Interference
Travel time reliability – biggest concern
 Delayed deliveries
 Unanticipated costs

 Emergency
response
Causes of Recurring Congestion
Non-recurring Congestion
Safety Impacts

Road user exposure to hazards
 Will
staging create safety hazards greater
than existing?

Worker exposure to traffic
 Staging
allow for positive protection?
Geometrics during phases
 Availability of law enforcement
 Speed reduction necessary/considered?

Business Impacts

Access
 Temporary


Signing
Pavement
 Advance


entrances
notification of phase changes
Keep owners informed
Work Schedules
 Christmas
 Weekends
shopping season
Residential Access Impacts

Keep residents
informed as project
begins and
progresses
 Neighborhood
association meetings,
newsletters, mailings,
etc.
 Maintain access if
possible
Incident Response Impacts

Ensure access to all areas for emergency
vehicles
 Hospitals
nearby?
 Trauma centers?

Plan to provide access within work site
 Identify
alternate routes
 Pre-sign for use during incidents?
Transit Impacts

Transit route through project?
 Bus
stops
 Alternate routes available
 Include in PR information
Pedestrian Impacts

MUTCD Part 6D:
 If
project affects the
movement of
pedestrians,
adequate pedestrian
access and
walkways shall be
provided.
Impact Assessment
Proactive versus reactive
 Use early in the TMP Development
process to identify and estimate the
magnitude of the impacts
 Assess impacts on regional basis
 Use assessment to help evaluate various
strategies for mitigating impacts
 Possibly use assessments to justify TCP
revisions after award of project

Goal

A good impact assessment process
should keep agency from being surprised
after project is underway – when it is too
late to consider strategies to reduce
impacts.
Mobility Impact Assessment
Tools

Historical knowledge – “Lane closures do not cause
backups on this segment of road…”

Various levels of tools for more detailed analysis
 Sketch Planning Tools
 Travel Demand Models
 Traffic Signal Optimization Tools
 Macroscopic Simulation Models
 Mesoscopic Simulation Models
 Microscopic Simulation Models
WZ Analysis Tool Model Spectrum
Transportation Model Approaches
macro
meso
micro
Macroscopic
Delay Estimation Tools

Basic Concept

macro


Strengths


Special-purpose delay
estimators for work
zones
Examples: QuickZone,
DELAYE, QUEWZ-98
Relatively easy-to-use,
rapid analysis
Weaknesses


Limited capability
beyond modeling simple
“pipeline” analyses
High-level analysis
Macroscopic
Regional Planning Models
macro

Basic Concept



Strengths


Steady-state liquid flow
Examples: TRANPLAN,
EMME/2, TransCAD,
others
Can handle very large
networks (metro areas)
Weaknesses


Not time sensitive
Complex models,
relatively expensive to
build and maintain
Mesoscopic

Basic Concept




Examples: DYNASMART-P, DYNAMEQ
Strengths


Particle Flow
Vehicles are located on roadways but not specific lanes
Can model sub-regional areas in major metropolitan areas
Weaknesses


Not detailed enough for some operational strategies (e.g., complex signal control)
Model complexity is high, data and calibration resources are significant
Microscopic

CORSIM, VISSIM, and others
 Model
individual vehicle movements
 Requires extensive resources to establish and
calibrate
 Usually reserved for large and complex
projects unless existing model can be utilized
Work Zone Analysis Primer


Aid in selection of the
correct tool to use in
the analysis
Provide guidance to
reviewer to ensure
appropriate tool was
selected for project
Work Zone Modeling and
Simulation

Volume IX
 Case
studies
 Aid for analysts
How Should Results of
Assessment Be Utilized?
Formulate policies
 Identify strategies that will minimize
impacts
 Identify critical issues to address in
development of TMP

 Alternate
route availability
 Effects on businesses and residents
Results Used to
Formulate Policy
Ohio DOT MOT/PLC Policy
TMP Development Process
Identify
Early in
Process
Analyzing
Strategies
MNDOT Specific – Fig. 1
Impacts Assessment at Project
Level

Consider WZ impacts in the assessments
that are performed during alternatives
evaluations.
 Allocate sufficient funds
 Address impacts of multiple projects
Work Zone Impacts Assessment
During Preliminary Engineering
1.
2.
3.
4.
5.
6.
Compile project /WZ Scope Information for
Alternatives
Assess WZ Impacts of Alternatives at a
Screening Level
Analyze Potential Impacts (optional)
Identify WZ Management Strategies
Perform Plan/Program Level WZ Impacts
Assessment
Compile Planning-Level Work Zone Strategy
Compile project /WZ Scope
Information for the Alternatives

The major categories of information that
may be needed include the following:
 Project
Scope
 Roadway/Traffic Characteristics
 Other Influencing Factors
Identify WZ Management
Strategies

Issues To Be Addressed In Identifying WZ
Management Strategies:
 TTC
Strategies
 TO and PI Strategies.
 Coordination Strategies with Other
Projects.
 Costs for the Management Strategies
How to Incorporate WZ Impacts
Assessments During Design




Compile Preliminary Engineering Materials
Reassess WZ Impacts
Develop/Recommend Final Construction
Staging and TMP
Advertise and Award Contract
Work Zone Impacts Assessment
During Construction





Assess the impact of any proposed changes prior to the
start of work
Implement the TMP.
Actively monitor and manage work zone impacts during
construction.
Revise the TMP and implement appropriate revisions, if
necessary.
Document any findings or lessons for use in
performance assessments.
Example Checklist
DDOT
Example Checklist
DDOT Guide
Example Checklist
DDOT Guide
Example Checklist
DDOT Guide
Michigan TMP Template
Michigan TMP Template
http://www.ops.fhwa.dot.gov/wz/resources/final_rule/mdot_tmp_templ
ate/mdot_tmp_template.pdf
Review and Discussion
When should the Impacts Assessment
take place in the TMP process?
 Does your state have a procedure in place
to assure impacts are factored in to the
project planning and design?
