Appendix D_Video Measurements.pdf

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Appendix D

Video Road Lane and Width Measurements

A. Number of Lanes

Using the digital roadway video, determine the number of lanes at the minimum reporting interval (usually 0.020 miles). The number of lanes is assessed according to pavement striping and should be assessed across whole of roadway.

1. In the case of narrow roads, the number of lanes is assessed according to a minimum lane width of 7 feet, regardless of pavement striping and traffic flow direction.

2. The value will be populated into the field ROAD_CONDITION.NO_LANES at the start of every route. And should be adjusted when the number of lanes changes.

3. Turnouts are to be considered turn lanes, and the number of lanes will increase at the appropriate records in the PMS_20 table when a turnout is present.

B. Pavement Width, Lane Width, Shoulder Width, and Bike Lane Width

It is the intention of FHWA to have the contractor collect pavement width, lane width, and shoulder width. These will be measured from the digital roadway images at specified intervals on all routes collected for distress.

1. When the route is specified to obtain pavement and lane widths

(ROUTE_ID.WIDTH_FLAG=YES), the contractor shall use video and software to obtain and report pavement and lane widths.

2. The contractor shall deliver to FHWA a WIDTHMEASURE table, documenting all mileposts at which width measurements were taken, the associated width(s), and the mileposts that those widths will be applied to.

Pavement Width Definition: From edge-of-pavement to edge-of-pavement.

Exceptions to this will be noted prior to collection.

Lane Width Definition: From inside of centerline striping to inside of fogline striping. When no fogline exists, from inside of centerline striping to edge-of-pavement. When no striping at all exists, Lane Width = Pavement Width/2

(applies to 2 lane roads, if road is wide enough for 3 lanes, divide by 3 and so on).

Paved Shoulder Width Definition: From inside of fogline to edge of pavement.

The shoulder width shall be measured in the primary direction or right side of road, when applicable.

Bike Lane Width Definition: When a “marked bike lane” (refer to MIRE 2.0 element # 41) is defined, a width of the bike lane shall be measured.

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3. Measure pavement, lane, shoulder (when applicable), and bike lane (when applicable) width at a frequency of every 0.5-mile or less along each route. On routes shorter than one mile in length, measure at a frequency adequate to establish an accurate and reasonable width for the length of the route. All width measurements shall be taken at straight, typical road tangents. No width measurements shall be taken at points affected by curves, curve widening, pullouts, intersections, or bridges.

4. Additional widths shall be measured wherever the typical design road section changes by +/- 1 feet.

5. Turnouts are considered turn lanes, and the pavement width increases at the appropriate records in the ROAD_CONDITION table when a turnout is present.

To obtain an accurate measurement in turnout lanes, merging lanes, merging ramps, or other lanes that taper, measure beginning of the taper or other representative point. This will ensure that the pavement and lane widths represent the average widths for that segment.

C. Quality Control Checks

1. EFLHD will conduct accuracy checks on width measurements on all routes using the same methodology and technology as provided by contractor software and video.

Contractor will provide all files necessary to allow EFLHD to perform quality control checks on the image measurement process to capture roadway measurements for all types of widths. All files shall be retrievable by EFLHD for independent QC verification of the contractor’s results using viewing software.

2. In addition, EFLHD will perform field width measurements on an EFLHD-determined sample of parks and routes throughout the life of the contract. Width values submitted by contractor will be compared to the field measurements and evaluated based on established QC requirements in the table below.

EFLHD will review the width measurements listed in the following table when conducting its quality control checks. The accuracy requirements listed below apply only to width measurements taken at typical roadway sections. Due to difficulties in checking measurements at sections with curves, tapering lanes, etc., EFLHD will perform quality control checks of width measurements only at typical roadway sections.

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Table D-1: Width Measurements from Roadway Video

D. DISTRESS LANE WIDTH VISIBLE IN PAVEMENT VIDEO

The distress lane width (D_LANE_WIDTH) should be measured from each individual pavement image. This should be measured from inside of centerline to inside of fogline. Conversely, the Lane Width (LANE_WIDTH) value measured from the roadway/forward facing video and populated to the

ROAD_CONDITION.LANE_WIDTH field is distinct from the distress lane width value used in calculating distresses and populated to the

ROAD_CONDITION.D_LANE_WIDTH field.

Distress Lane Width Definition: From inside of fogline to inside of centerline. In situations where neither a fogline nor a centerline are present, measure from the pavement edge inward, using the lane width measurement as a guideline.

WIDTH MEASUREMENTS

ROADWAY VIDEO

Data

Element

Location

Method Precision Accuracy Location

Location

Depicted on

Video

Lane

Width Video Analysis 1 decimal <= 1.0 foot

Milepost at width measurement

Measurement

Location Delineated on Corresponding

Video jpeg image

Pavement

Width Video Analysis 1 decimal <= 1.0 foot

Milepost at width measurement

Measurement

Location Delineated on Corresponding

Video jpeg image

Shoulder

Width Video Analysis 1 decimal <= 1.0 foot

Milepost at width measurement

Measurement

Location Delineated on Corresponding

Video jpeg image