Unsignalized Intersection Collisions

Index of Strategies by Implementation Timeframe and Relative Cost

Exhibit IV-1 provides a classification of strategies according to the expected timeframe and relative cost for this emphasis area. In several cases, the implementation time will be dependent upon such factors as the agency's procedures, the need for additional right-of-way, the number of stakeholders involved, and the presence of any controversial situations. The range of costs may also be somewhat variable for some of these strategies because of many of the same factors. Placement in the table below is meant to reflect costs relative to the other strategies listed for this emphasis area only. The estimated level of cost is for the commonly expected application of the strategy, especially one that does not involve additional right-of-way, or major construction, unless it is an inherent part of the strategy.

EXHIBIT IV-1
Index of Strategies by Implementation Timeframe and Relative Cost

		Relative Cost to Implement and Operate
Timeframe for Implementation		Low	Moderate	Moderate to High	High
Short (less than a year)	17.1 A2—Implement driveway turn restrictions	X
	17.1 B4—Provide bypass lanes on shoulders at T-intersections	X
	17.1 B11—Restrict or eliminate turning maneuvers by signing	X
	17.1 B12—Restrict or eliminate turning maneuvers by providing channelization or closing median openings	X
	17.1 C1—Clear sight triangles on stop- or yield-controlled approaches to intersections	X
	17.1 C2—Clear sight triangles in the medians of divided highways near intersections	X
	17.1 C4—Eliminate parking that restricts sight distance	X
	17.1 D3—Retime adjacent signals to create gaps at stop-controlled intersections	X
	17.1 E1—Improve visibility of intersections by providing enhanced signing and delineation	X
	17.1 E4—Provide a stop bar (or provide a wider stop bar) on minor-road approaches	X
	17.1 E5—Install larger regulatory and warning signs at intersections	X
	17.1 E6—Call attention to the intersection by installing rumble strips on intersection approaches	X
	17.1 E7—Provide dashed markings (extended left edgelines) for major roadway continuity at divided highway intersections	X
	17.1 E8—Provide supplementary stop signs mounted over the roadway	X
	17.1 E9—Provide pavement markings with supplementary messages, such as STOP AHEAD	X
	17.1 E10—Provide improved maintenance of stop signs	X
	17.1 E11—Install flashing beacons at stop-controlled intersections	X
	17.1 F2—Provide all-way stop control at appropriate intersections	X
	17.1 G1—Provide targeted enforcement to reduce stop sign violations		X
	17.1 G2—Provide targeted public information and education on safety problems at specific intersections	X
	17.1 H1—Provide targeted speed enforcement		X
	17.1 H3—Post appropriate speed limit on intersection approaches	X
	17.1 I1—Provide turn path markings	X
	17.1 I2—Provide a double yellow centerline on the median opening of a divided highway at intersections	X
	17.1 I3—Provide lane assignment signing or marking at complex intersections	X
Medium (1 to 2 years)	17.1 A1—Implement driveway closures/relocations		X
	17.1 B1—Provide left-turn lanes at intersections		X
	17.1 B2—Provide longer left-turn lanes at intersections		X
	17.1 B3—Provide offset left-turn lanes at intersections			X
	17.1 B5—Provide left-turn acceleration lanes at divided highway intersections		X
	17.1 B6—Provide right-turn lanes at intersections		X
	17.1 B7—Provide longer right-turn lanes at intersections		X
	17.1 B8—Provide offset right-turn lanes at intersections			X
	17.1 B9—Provide right-turn acceleration lanes at intersections		X
	17.1 B10—Provide full-width paved shoulders in intersection areas		X
	17.1 B14—Convert four-legged intersections to two T-intersections				X
	17.1 B15—Convert offset T-intersections to four-legged intersections				X
	17.1 B16—Realign intersection approaches to reduce or eliminate intersection skew				X
	17.1 B17—Use indirect left-turn treatments to minimize conflicts at divided highway intersections		X
	17.1 B18—Improve pedestrian and bicycle facilities to reduce conflicts between motorists and nonmotorists^a		X
	17.1 D1—Provide an automated real-time system to inform drivers of the suitability of available gaps for making turning and crossing maneuvers		X
	17.1 D2—Provide roadside markers or pavement markings to assist drivers in judging the suitability of available gaps for making turning and crossing maneuvers	X
	17.1 E2—Improve visibility of the intersection by providing lighting			X
	17.1 E3—Install splitter islands on the minor-road approach to an intersection		X
	17.1 H2—Provide traffic calming on intersection approaches through a combination of geometrics and traffic control devices		X
Long (more than 2 years)	17.1 B13—Close or relocate high-risk intersections				X
	17.1 C3—Change horizontal and/or vertical alignment of approaches to provide more sight distance				X
	17.1 F1—Avoid signalizing through roads^b				X
	17.1 F3—Provide roundabouts at appropriate locations				X
^aWhile there is expected to be wide variation of cost and time to implement for most of the strategies, this strategy is particularly subject to variation. The estimate shown is considered to be the middle of the range. ^bWhile it is possible to install all-way stop control at relatively low cost and do so within a year, the strategy is classified to reflect the greater majority of options, which are costly and require a long time for design development and construction.