Two-Way STOP-Controlled Intersections

The compute engine reproduces the published HCM worked examples for this chapter and applies the December 2022 HCM corrections, including the corrected Stage II conflicting movements and the Exhibit 20-14 swap. The pedestrian mode reproduces all three scenarios of Chapter 32 Example Problem 2, with the caveat noted there that two coefficients of Equation 20-95 are clipped out of the published text and were recovered by fitting that example. Verify results independently before relying on them in engineering work, and please report discrepancies on GitHub.

Analysis Mode

Section 4 evaluates the vehicular movements at the intersection. Section 5 evaluates a pedestrian crossing the uncontrolled major-street traffic stream, which is a separate procedure with its own service measure. The same Section 5 method applies to a midblock crossing.

Chapter 20 Mode

Geometry

Legs, major-street cross section, and minor-approach lane allocation. The major street runs east-west and the minor stem of a three-leg intersection is northbound.

Intersection Type

Major Lanes per Direction

Major Right Turn (EB)

Major Right Turn (WB)

Minor Lanes (NB)

Minor Lanes (SB)

Ignored for a three-leg intersection.

Minor Approach Grade (NB)

Minor Approach Grade (SB)

Hover the legend to highlight an approach. The dash pattern shows each movement's HCM rank, and in the 2D view the movement volumes can be edited directly on the diagram.

The dash pattern shows the HCM rank: solid rank 1 (major through and right), long dashes rank 2 (major left, minor right), short dashes rank 3, dotted rank 4. Lower rank yields to everything above it. Animated traffic runs the major street free and, after a run, crawls the minor approaches by their LOS. An illustration, not a simulation.

Demand

Turning-movement volumes numbered per HCM Exhibit 20-1. Movements 10 to 12 apply to four-leg intersections only.

Mv 1 · Major EB Left

veh/h

Mv 1U · Major EB U-Turn

veh/h

Mv 2 · Major EB Through

veh/h

Mv 3 · Major EB Right

veh/h

Mv 4 · Major WB Left

veh/h

Mv 4U · Major WB U-Turn

veh/h

Mv 5 · Major WB Through

veh/h

Mv 6 · Major WB Right

veh/h

Mv 7 · Minor NB Left

veh/h

Mv 8 · Minor NB Through

veh/h

Mv 9 · Minor NB Right

veh/h

Mv 10 · Minor SB Left

veh/h

Mv 11 · Minor SB Through

veh/h

Mv 12 · Minor SB Right

veh/h

Traffic

Peaking and traffic-stream characteristics.

Peak Hour Factor

Leave blank if the demand values are already peak 15-min flow rates.

Heavy Vehicles

Analysis Period

Outputs

Results populate after pressing Calculate.

Movement	Flow Rate (veh/h)	Capacity (veh/h)	Delay (s/veh)	LOS	95% Queue (veh)

Intersection Delay (s/veh):

LOS is reported per movement and per lane. The HCM does not define a LOS letter for a TWSC intersection as a whole.