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BALL-BANK INDICATOR STUDIES

Imperial Traffic & Data Collection performs Ball-Bank Indicator studies to evaluate vehicle response and operating conditions along horizontal curves.

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Using a calibrated digital ball-bank indicator, ITDC documents vehicle speed and ball-bank readings through each curve. The resulting field data can support advisory-speed evaluations, curve-warning-sign reviews, roadway safety studies, and engineering analysis.

 

What is a ball-bank study?

A ball-bank indicator measures the combined effects of roadway curvature, vehicle speed, roadway superelevation, and vehicle body roll as a vehicle travels through a horizontal curve. Multiple controlled test runs provide objective field data that engineers and roadway agencies can use when evaluating curve performance and recommended advisory speeds.

 

Why conduct a ball-bank study?

  • Establish or verify recommended curve advisory speeds

  • Reevaluate advisory speeds following changes in roadway conditions

  • Investigate curves with run-off-road or speed-related crash histories

  • Evaluate driver response and vehicle behavior through horizontal curves

  • Review the need for horizontal-alignment warning signs

  • Assess advisory-speed plaques, chevrons, and delineation

  • Support roadway safety audits and corridor safety studies

  • Provide field data for roadway rehabilitation or reconstruction projects

  • Evaluate reverse curves, compound curves, and successive curve conditions

  • Supplement geometric, speed, and crash analyses

 

How ITDC performs the study

  1. Location review
    ITDC reviews the study limits, curve configuration, travel directions, existing signing, roadway conditions, and requested testing requirements.

  2. Equipment preparation
    A calibrated Rieker digital ball-bank indicator and synchronized roadway video equipment are installed in the test vehicle.

  3. Controlled field runs
    A trained technician drives each curve in both directions. Multiple runs are performed at controlled speeds under appropriate pavement, weather, and free-flow traffic conditions.

  4. Data documentation
    ITDC records the test speed, direction of travel, maximum ball-bank reading, roadway and weather conditions, and relevant field observations.

  5. Data compilation
    Test results, roadway video, and field observations are organized for client review and engineering analysis.

 

Data collected

  • Curve identification and location

  • Direction of travel

  • Test-run speed

  • Maximum ball-bank reading

  • Multiple runs at incremental speeds

  • Pavement and weather conditions

  • Roadway and curve observations

  • Existing advisory speed, when applicable

  • Existing curve warning signs and traffic-control devices, if included

  • Time-synchronized forward-facing roadway video

 

Deliverables

  • Ball-bank results summarized by curve, direction, and test speed

  • Field data tables

  • Maximum recorded ball-bank values

  • Roadway dash-camera video

  • Field photographs, when required

  • Field notes and roadway observations

  • Electronic copies of collected data

  • Map or location summary of evaluated curves

 

Related and optional services

  • Roadway speed studies

  • Approach and curve operating-speed data

  • Automatic Traffic Recorder counts

  • Crash-data compilation

  • Existing signing inventory

  • Curve-warning-sign and chevron inventory

  • Roadway pavement-marking inventory

  • Traffic-control-device evaluation

  • Dash-camera roadway documentation

  • Horizontal-curve geometry collection

  • Before-and-after safety evaluations

 

Common applications

  • Local and county roadway safety programs

  • High-crash curve evaluations

  • Rural roadway studies

  • Horizontal-curve signing programs

  • Road safety audits

  • Systemic safety evaluations

  • Corridor rehabilitation projects

  • Pavement resurfacing programs

  • Local Road Safety Plans

  • HSIP and other safety-funding applications

  • Reviews prompted by public or agency concerns

 

Digital field documentation

ITDC uses a Rieker digital electronic ball-bank indicator to provide consistent digital readings during curve testing. Field measurements can be paired with synchronized forward-facing video, allowing the roadway conditions and ball-bank results to be reviewed together.

 

Evaluating horizontal curves or existing advisory speeds?

Send us the roadway, study limits, curve locations, and desired supporting services. ITDC can provide standalone ball-bank testing or coordinate the work with speed, traffic-volume, signing, and crash-data evaluations.

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