For Further Information

The scan final report, 

“BEST PRACTICES 

IN WORK ZONE 

ASSESSMENT, DATA 

COLLECTION AND 

PERFORMANCE 

EVALUATION Scan 

08‐04,” is available 

online at www.trb.org (search under 

NCHRP 20-68A, U.S. Domestic Scan 

Program).

The Scan Team

 » FHWA

 » North Carolina DOT

 » California DOT

 » Ohio DOT

 » Maryland DOT

 » New Hampshire DOT

» Colorado DOT

» Michigan DOT

» Texas Transportation Institute

Domestic Scan of

Work Zone Assessment, 

Data Collection 

and Performance 

Measurement Practices

NCHRP 20-68A

US Domestic 

Scan Program

Scan 08-04

March 2011

Background

Transportation agencies 

across the nation regularly 

implement strategies to 

alleviate congestion and 

improve safety in work 

zones. To help agencies 

improve on these efforts 

over time, the Work Zone Safety and Mobility 

Rule requires agencies to use safety and 

operational data to manage impacts and 

assess performance on individual projects 

and overall. Agencies need to collect and 

analyze safety and operational data to 

have the necessary information to better 

understand the performance of work 

zones and evaluate the effectiveness of 

work zone management strategies. Metrics 

such as queues, delay, and crashes can 

help agencies improve their policies and 

processes to better address work zone 

impacts - and thereby reduce work zone 

congestion and improve safety. Agencies 

could benefit from information on how their 

peers develop measures, collect data, and 

evaluate work zone performance.

A 2010 Domestic Scan of best practices in 

work zone assessment, data collection, and 

performance measurement documented 

practices that are being employed to ensure 

safety and minimize congestion in work 

zones. The purpose of this brochure is to share 

information on practices found during the 

scan and provide the key findings, challenges, 

and recommendations from the scan.

U.S. Department 

of Transportation

Federal Highway

Administration

U.S. Department 

of Transportation

Federal Highway

Administration

The Domestic Scan

The scan team identified 

four main topics to target:

» Assessing the safety and 

congestion/operational 

performance of work 

zones. 

» Collecting the data for these measures.

» Using the data to make improvements 

in work zone performance and 

management.

» Identifying processes, methods and/

or tools used to assess impacts during 

various stages of project development 

(planning, design, construction). 

Scan Methodology

A desk scan, performed in the fall of 2009, 

identified agencies that had implemented 

or were implementing practices in each 

of the main topic areas. The scan team 

identified a total of 15 agencies and 

followed up with each to gather additional 

information for the scan. 

A combination of on-site interviews, 

reverse scans (where the agency travels 

to meet with the scan team at a location), 

and webinars/videoconferences were 

employed to gather the desired data 

from agencies. The scanning effort was 

completed over two weeks in March 2010. 

Pub. No. FHWA-HOP-11-021
Data Sources

Sources of Work Zone 

Safety Data

» Police crash reports

» DOT supplemental crash 

data collection

» Inspection reports

» Service patrol/fire department calls

» TMC incident reports

» Customer complaints

Sources of Work Zone Mobility/

Operational Data

» Visual inspection of acceptable travel 

conditions manually or via cameras

» Manual sampling of travel times, speeds, 

queue lengths

» Electronic monitoring of speeds, volumes, 

lane occupancies

» Electronic monitoring of elapsed travel 

times via Bluetooth or other technology

» User complaints and surveys

Some agencies require work zone monitoring 

in Transportation Management Plans. The 

tendency is to use performance measures 

mainly on large-scale projects. Some 

agencies use technology to capture work zone 

performance information, such as through 

traffic management centers, temporary ITS, 

or third party data suppliers while others use 

customer surveys and qualitative observations 

to assess work zone performance. 

Key Findings

» Safety measures tend 

to be developed and 

examined mostly at the 

program level 

» Mobility measures tend 

to be developed and 

examined mostly at the project level

» Agencies tend to select either safety or 

mobility measures to focus on, but not 

both

» Electronic data entry processes, along with 

electronic databases and technologies 

for collecting data, help promote use of 

performance measures and analyses

» Agencies benefit more from early 

consideration of work zone impacts in the 

project development process

» Permitted lane closure tools are commonly 

used to estimate impacts from capacity 

restrictions 

Agency Challenges

Some challenges that agencies face 

include:

» Obtaining upper management buy-in on 

using performance measures

» Determining appropriate levels of 

performance monitoring for projects

» Obtaining field personnel buy-in for the 

level of effort needed

DOTs Scanned:

» California DOT

» Florida DOT

» Illinois Tollway Authority

» Indiana DOT

» Maryland DOT

» Michigan DOT

» Missouri DOT

» New Hampshire DOT

» New Jersey DOT

» New York State DOT

» Ohio DOT

» Oregon DOT

» Pennsylvania DOT

» Washington State DOT

» Wisconsin DOT

Performance Measures

Work Zone Safety Performance 

Measures Currently in Use

» Number of crashes

» Percentage of crashes in 

various categories

» Crash rates

» Crash costs

» Service patrol dispatch 

frequency

» Fire department dispatch 

frequency

» Speeds

» Speeding citation frequency

» Inspection scores

» Worker fatalities and injuries

» Work zone intrusion 

frequency

Work Zone Mobility and Operational 

Performance Measures Currently in Use

» Delay per vehicle

» Queue length

» Duration of queue

» Volume/capacity ratio

» Level-of-service

» Volume (throughput)

» Percentage of time at free-flow speed

» Percentage of work zones meeting 

expectations for traffic flow

» User complaints