Details:

Creators:
Coifman, Benjamin ; Kim, Seoungbum
Coifman, Benjamin ; Kim, Seoungbum Less -
Corporate Creators:
Ohio State University
Corporate Contributors:
United States. Federal Highway Administration
Subject/TRT Terms:
[+]
Data Collection Freeways Loop Detectors Performance Measurement Sensors Traffic Data Traffic Surveillance
Publication/ Report Number:
FHWA/OH-2013/21
Resource Type:
Tech Report
Geographical Coverage:
Ohio
Corporate Publisher:
Ohio. Dept. of Transportation. Office of Statewide Planning and Research
Abstract:
Until recently freeway traffic operations data were collected in house by the Ohio Department of

Transportation (ODOT) using loop detectors. In recent years several private companies have emerged with a

viable opportunity to outsource traffic data collection. While these new business models and ease of

deployment are compelling, there are few published studies explicitly evaluating their performance. ODOT has

contracted with two of these data providers: SpeedInfo and INRIX. This study exploited a unique juncture as

ODOT transitioned to the new third party data collection: the two new systems and the legacy loop detectors

were concurrently operational in Columbus, OH for approximately 6 months. Using the archived data from this

period, we evaluated SpeedInfo and INRIX performance over a 14 mi. This long period of time ensured that we

would have a better chance of observing intermittent features that might go unobserved in a short-term study.

Both SpeedInfo and INRIX traffic data generally performed within specifications, exhibiting small biases

that could likely be fixed with fine-tuning. Both sensors also exhibited a reporting lag, on the order of 60 sec for

SpeedInfo and 360 seconds for INRIX (comparable to conventional 60 sec and 5 min aggregation periods used

in loop detectors). Although the lag and bias are within specifications, some applications might be sensitive to

them, e.g., traffic responsive ramp metering. Each system also exhibited unique behavior not found in the other.

SpeedInfo is sensitive to precipitation: sometimes going offline for tens of minutes. When mounted on the

shoulder, SpeedInfo showed slightly degraded performance on the far side traffic. INRIX reported speeds every

minute, but after excluding repeated values, the actual effective reporting period was more like 3-5 min, with

occasional periods of repeated measurements lasting in excess of 10 min (already reflected in the lag above).

INRIX also provides two measures of confidence, neither of which reflects the measurement repetition.


Format:
PDF
Funding:
State Job Number 134723
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:1937021f91ff9e47e81b5e48cf5234903e18356eee850509a6428f04418aa8e6
Download URL:
https://rosap.ntl.bts.gov/view/dot/26979/dot_26979_DS1.pdf
File Type:

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