HCM Chapter 10

Freeway Facilities Core Methodology

Evaluate a directional freeway facility of basic, merge, diverge, weaving, and overlapping ramp segments over consecutive 15-min analysis periods. Covers the mixed-flow core methodology, optional per-segment work zones, and an optional adjacent managed lane analyzed as a parallel lane group.

Open in Builder Takes this form to the facility builder as a Chapter 10 fixture. A freeway fixture records segments and not the ramps behind them, so it arrives there as a segment table with no feature layer.
The compute engine reproduces the published HCM worked examples for this chapter at the facility level. On an oversaturated facility the placement of a queue among upstream segments can differ from the published engine while the facility totals agree. Verify results independently before relying on them in engineering work, and please report discrepancies on GitHub.

Facility

Values that apply to the whole facility in the analysis direction.

mi/h
%

Use 1.00 when the demand values are true 15-min flow rates.

pc/mi/ln
%
/mi
/mi

Used by weaving segments. Blank uses the total ramp density.

Demand

Mainline demand entering the facility, one value per 15-min analysis period.

veh/h

Comma-separated list. The number of values sets the number of analysis periods.

Segments

Ordered upstream to downstream. The facility must begin and end with a basic segment. Ramp demand lists carry one value per analysis period and missing values count as zero.

Segment 1 · Basic1BasicSegment 2 · Merge2MergeSegment 3 · Basic3Basic

Segment chain, upstream to downstream. Widths follow segment length; press Calculate to color each segment by its per-period LOS.

#TypeLength (ft)LanesOn-Ramp Demand (veh/h)Off-Ramp Demand (veh/h)Ramp FFS (mi/h)Accel Lane (ft)Decel Lane (ft)Work Zone
1
2
3

Adjacent Managed Lane

Optional. Analyzes a parallel managed lane group alongside the general-purpose lanes (HCM Chapter 10 Steps A-9 through A-17, Chapter 25 Section 2), reporting the two lane groups and their combination. Enabling loads the Example Problem 5 managed lane, a one-lane continuous-access facility.

Outputs

Results populate after pressing Calculate.

Facility Performance
Space Mean Speed (mi/hr):
Average Density (veh/mi/ln):
Facility LOS:

Facility Length:

Overall Space Mean Speed:

Overall Density:

Oversaturated: