Lecture #10 Chapter 15: Intersection Control

Objective 1.Hierarchy of Intersection Control 2.Assessing Basic Rules-of-the-Road 3.Assessing Need for Signalization 4.Stop and Yield Control

Hierarchy of Intersection Control What are the fundamental rules of the road? –Basic rules-of-the road Apply at any intersection not controlled by STOP, YIELD, or signal What are these rules? –STOP or YIELD control ROW goes to uncontrolled approaches STOP—must stop YIELD—must slow to 10 mph or less –Signal control

Hierarchy of Intersection Control When should these controls be used? –Basic rules of the road –YIELD control –STOP control –Signal control

Assessing the Viability of Basic Rules-of-the-Road What is the primary prerequisite for safety under the basic rules-of-the-road? –Sight distance must be adequate

Assessing the Viability of Basic Rules-of-the-Road Rules for insuring adequate sight distance (must be applied to all four corners): –at least 1 safe stopping distance, and –30 ft separation –The above are necessary but not sufficient conditions

Assessing the Viability of Basic Rules-of-the-Road SSD A ; d A = SSD A actual d B given SSD A SSD B given d A = SSD A Compare SSD B and d B

Assessing the Need for Signalization When should a traffic signal be installed? –When at least one of eleven warrants is satisfied.

Traffic Signal Warrants 1) Minimum vehicular volume 2) Interruption of continuous traffic— 3) Minimum pedestrian volume— 4) School crossing— 5) Progressive movement— 6) Accident experience— 7) Systems warrant— 8) Combination of warrants— 9) Four-hour vehicular volume— 10) Peak-hour delay—

Stop and Yield Control Three forms of control –YIELD (one or two approaches) –STOP control for minor approaches (one or two) –All-way stop MUTCD (caution)—inappropriate use of stop signs –At traffic signals –Speed control –Through ways of an expressway

Stop and Yield Control Warrants for STOP signs {Figure 15-19} –Intersection of a less important road with a main road where application of the normal right of way rule is hazardous –Street entering a through highway or street –Unsignalized intersection in a signalized area –combination of highway speed, restricted view, and serious accident record

Stop and Yield Control Warrants for YIELD signs {Figure 15-20} –necessary to assign right-or-way with safe speed > 10 mph –Entrance ramp w/o acceleration lane –Intersections on divided highways –Separate channelized right-turn lane with inadequate acceleration lane –Special problems shown by study to be rectified by YIELD sign