HCM Chapter 19

Signalized Intersections

Estimate control delay and level of service for a four-leg pretimed signalized intersection, by approach and for the intersection as a whole.

The compute engine reproduces the published HCM worked examples for this chapter. This page exposes a simplified pretimed configuration. Parking, bus stops, grades, platooning, and actuated phase timing are analyzed at their base values. Verify results independently before relying on them in engineering work, and please report discrepancies on GitHub.

Signal and Site

Cycle timing and intersection-wide characteristics. Phase durations include the change period (G + Y + Rc), and the northbound and southbound approaches share one street phase pair with the eastbound and westbound approaches on the other.

s
pc/h/ln
s
s
%
mph
ft
p/h

Hover the legend to highlight an approach's movements. The picture follows the lane and phasing inputs, and in the 2D view the movement volumes can be edited directly on the diagram.

NB
SB
EB
WB

Movement volumes are left / through / right. A dashed left-turn path runs permitted; a solid one has a protected phase. Animated platoons discharge on their street's green and, after a run, stretch with the approach LOS. A timed illustration, not a simulation.

Northbound Approach

Demand volumes, lanes, and phase durations for the NB approach. Set the left phase to 0 for a permitted left turn.

veh/h
veh/h
veh/h

A right turn without an exclusive lane shares the rightmost through lane.

s
s

Requires an exclusive left lane. Use 0 for a permitted left turn.

Southbound Approach

Demand volumes, lanes, and phase durations for the SB approach. Set the left phase to 0 for a permitted left turn.

veh/h
veh/h
veh/h

A right turn without an exclusive lane shares the rightmost through lane.

s
s

Requires an exclusive left lane. Use 0 for a permitted left turn.

Eastbound Approach

Demand volumes, lanes, and phase durations for the EB approach. Set the left phase to 0 for a permitted left turn.

veh/h
veh/h
veh/h

A right turn without an exclusive lane shares the rightmost through lane.

s
s

Requires an exclusive left lane. Use 0 for a permitted left turn.

Westbound Approach

Demand volumes, lanes, and phase durations for the WB approach. Set the left phase to 0 for a permitted left turn.

veh/h
veh/h
veh/h

A right turn without an exclusive lane shares the rightmost through lane.

s
s

Requires an exclusive left lane. Use 0 for a permitted left turn.

Outputs

Results populate after pressing Calculate.

ApproachFlow Rate (veh/h)Control Delay (s/veh)LOS
NB
SB
EB
WB
Intersection Control Delay (s/veh):
Critical Volume-to-Capacity Ratio Xc: