Search Safety:

Toolbox of Countermeasures andTheir Potential Effectiveness for Intersection Crashes

Introduction

This issue brief documents estimates of the crash reduction that might be expected if a specific countermeasure or group of countermeasures is implemented with respect to intersection crashes. The crash reduction estimates are presented as Crash Reduction Factors (CRFs).

Traffic engineers and other transportation professionals can use the information contained in this issue brief when asking the following types of question: Which countermeasures might be considered at the signalized intersection of Maple and Elm streets, an intersection experiencing a high number of total crashes and left-turn crashes? What change in the number of total crashes and left-turn crashes can be expected with the implementation of the various countermeasures?

Crash Reduction Factors

A CRF is the percentage crash reduction that might be expected after implementing a given countermeasure. In some cases, the CRF is negative, i.e. the implementation of a countermeasure is expected to lead to a percentage increase in crashes.

One CRF estimate is provided for each countermeasure. Where multiple CRF estimates were available from the literature, selection criteria were used to choose which CRFs to include in the issue brief:

• Firstly, CRFs from studies that took into account regression to the mean and changes in traffic volume were preferred over studies that did not.
• Secondly, CRFs from studies that provided additional information about the conditions under which the countermeasure was applied (e.g. road type, area type) were preferred over studies that did not.

Where these criteria could not be met, a CRF may still be provided. In these cases, it is recognized that the reliability of the estimate of the CRF is low, but the estimate is the best available at this time. The CRFs in this issue brief may be periodically updated as new information becomes available.

The Desktop Reference for Countermeasures lists all of the CRFs included in this issue brief, and adds many other CRFs available in the literature. A few CRFs found in the literature were not included in the Desktop Reference. These CRFs were considered to have too large a range or too large a standard error to be meaningful, or the original research did not provide sufficient detail for the CRF to be useful.

A CRF should be regarded as a generic estimate of the effectiveness of a countermeasure. The estimate is a useful guide, but it remains necessary to apply engineering judgment and to consider site-specific environmental, traffic volume, traffic mix, geometric, and operational conditions which will affect the safety impact of a countermeasure. The user must ensure that a countermeasure applies to the particular conditions being considered. The reader is also encouraged to obtain and review the original source documents for more detailed information, and to search databases such as the National Transportation Library (ntlsearch.bts.gov) for information that becomes available after the publication of this issue brief.

Presentation of the Crash Reduction Factors

In the Tables presented in this issue brief, the crash reduction estimates are provided in the following format:

CRF(standard error)^REF

The CRF is the value selected from the literature.

The standard error is given where available. The standard error is the standard deviation of the error in the estimate of the CRF. The true value of the CRF is unknown. The standard error provides a measure of the precision of the estimate of the true value of the CRF. A relatively small standard error indicates that a CRF is relatively precisely known. A relatively large standard error indicates that a CRF is not precisely known. The standard error may be used to estimate a confidence interval of the true value of the CRF. (An example of a confidence interval calculation is given below.)

The REF is the reference number for the source information.

As an example, the CRF for the countermeasure install cameras to detect red-light running for right-angle fatal/injury crashes is:

16(6)²⁷

The following points should be noted:

• The CRF of 16 means that a 16% reduction in right-angle fatal/injury crashes is expected after the installation of red-light running cameras.
• This CRF is bolded which means that a) a rigorous study methodology was used to estimate the CRF, and b) the standard error is relatively small. A CRF which is not bolded indicates that a less rigorous methodology (e.g. a simple before-after study) was used to estimate the CRF and/or the standard error is large compared with the CRF.
• The standard error for this CRF is 6. Using the standard error, it is possible to calculate the 95% confidence interval for the potential crash reduction that might be achieved by implementing the countermeasure. The 95% confidence interval is ±2 standard errors from the CRF. Therefore, the 95% confidence interval for the installation of red-light running cameras for right-angle fatal/injury crashes is between 4% and 28% (16 - 2×6 = 4%, and 16 + 2×6 = 28%).
• The reference number is 27 (Persaud et al., as listed in the References at the end of this issue brief).

Using the Tables

The CRFs for intersection crashes are presented in three tables which summarize the available information. The Tables are:

• Table 1: Signalization Countermeasures, which includes signal operations countermeasures, signal hardware countermeasures, and combination signal and other countermeasures
• Table 2: Geometric Countermeasures, which includes left turn countermeasures, right turn countermeasures, and other geometric countermeasures
• Table 3: Signs/Markings/Operational Countermeasures, which includes signs, pavement markings modifications, regulatory, lighting, and operational countermeasures

Readers familiar with the previous edition of this issue brief will notice the following changes:

• Countermeasure cost estimates of low, medium, high are no longer provided as most agencies have readily available cost estimate information with actual dollar amounts.
• Countermeasures that do not have an estimate of crash reduction effectiveness are no longer included.

The following points should be noted:

• Where available, separate CRFs are provided for different crash severities. The crash severities are: all, fatal/injury, fatal, injury, or property damage only (PDO).
• Where available, existing traffic control information is provided (i.e. the conditions existing before implementation of a countermeasure). The control information may be no signal, signal, stop, or stop/ yield. “Undefined” is used when a publication does not provide more specific information such as no signal, signal, stop, or yield controlled.
• Where available, the Tables provide daily traffic volume(vehicles/day) information for the major and minor roads of the intersection where the potential effectiveness of the countermeasure was measured. Where only one volume is provided, this volume refers to the traffic volume on the major road, unless otherwise specified.
• Blank cells mean that no information is reported in the source document.
• For additional information, please visit the FHWA Office of Safety website (safety.fhwa.dot.gov).

Legend CRF(standard error)REF CRF is a crash reduction factor, which is an estimate of the percentage reduction that might be expected after implementing a given countermeasure. A number in bold indicates a rigorous study methodology and a small standard error in the value of the CRF. Standard error, where available, is the standard deviation of the error in the estimate of the CRF. REF is the reference number for the source information. additional crash types identified in the Other Crashes column: a: Head-on b: run-off-road c: overturn d: night e: Day f: multiple-vehicle g: fixed-object h: older-driver i: Younger-driver j: right-turn k: speed-related l: speed related/day m: speed related/night n: speed related/dry o: speed related/wet p: Wet q: night/wet r: Pedestrian s: all turns t: bicycle u: emergency vehicle

Table 1: Signalization Countermeasures

Countermeasure(s)	Crash Severity	Control	Area Type	Configuration	All Crashes	Left-turn Crashes	Rt-angle Crashes	Rear-end Crashes	Sideswipe Crashes	Other Crashes	Major/Minor Daily Traffic Volume (vehicles/day)
SIGNAL OPERATIONS COUNTER MEASURES
Add all-red clearance interval (from 0 to 1 second)	All	Signal	Urban				0(44)28
Add exclusive pedestrian phasing	All	Signal								r    3416
Convert exclusive leading protected to exclusive lagging protected	All	Signal			-15(19)15	-49(54)15
Convert permissive or permissive/ protected to protected only left-turn phasing	All					9941
Convert permissive to permissive/ protected left-turn phasing	All					1641
Convert protected left-turn phase to protected/permissive	All	Signal			-20(17)15	-65(71)15		4(22)15
	Fatal/Injury	Signal			-10(25)15
Convert protected/permissive left-turn phase to permissive/protected	All	Signal			13(19)17	33(22)17
Improve signal timing [to intervals specified by the ITE Determining Vehicle Change Intervals: A Proposed Recommended Practice (1985)]	All	Signal		4-Leg	8(9)30		4(18)30	-12(16)30		h    4225
	All	Signal	All							f    511
	All	Signal				759
	Fatal/Injury	Signal				559	309			a    759
	Fatal/Injury	Signal								b    629
	Fatal/Injury	Signal		4-Leg	12(9)30		-6(22)30	-8(17)30
	Fatal/Injury	Signal	All							f    911
	Fatal/Injury	Signal								r    3730
	PDO	Signal				639	469	179		b    289
Increase yellow change interval	All	Signal			159		309
Install emergency vehicle pre-emption systems	All	Signal								u    7031
Modify signal phasing (implement a leading pedestrian interval)	All	Signal								r    516
Provide actuated signals	All	Signal				809	109
Provide Advanced Dilemma Zone Detection for rural high speed approaches	Fatal/Injury	Signal	Rural	4-Leg (1 app)	3940
Provide protected left-turn phase	Fatal/Injury All	Signal	Urban			16(2)19	19(2)19	279
	All	Signal			309	419	549	279		c    279	<5,000/lane (Total)
	All	Signal			369	469	569	359		c    359	>5,000/lane (Total)
	All	Signal			279	489	639	319		c    319
Provide protected/permissive left-turn phase (leading flashing green) (Request MUTCD Experimentation)	Fatal/Injury	Signal	Urban			16(4)19	12(4)19
Provide protected/permissive left-turn phase (leading green arrow)	Fatal/Injury	Signal	Urban			17(2)19	25(2)19
Provide signal coordination	All	Signal					3216
Provide split phases	All	Signal			2516
Remove flash mode (late night/ early morning)	All	Signal			2916		75(19)28
Replace existing WALK / DON'T WALK signals with pedestrian count down signal heads	All	Signal	Urban							r    2520
Signal HARDWARE COUNTERMEASURES
Add 3-inch yellow retroreflective sheeting to signal backplates	All	Signal	Urban		15(51)33
Add additional signal and upgrade to 12-inch lenses	All	Signal		4-Leg						h    3125
	All	Signal		4-Leg						i    1725
Add signal (additional primary head)	All	Signal	Urban	4-Leg	287		357	287
	Fatal/Injury	Signal	Urban	4-Leg	177
	PDO	Signal	Urban	4-Leg	317
Convert signal from pedestal-mounted to mast arm	All	Signal			4931	1231	7431	4131
	Fatal/Injury	Signal			4431
	PDO	Signal			5131
Improve visibility of signal heads (increase signal lens size, install new backboards, add reflective tape to existing backboards, and/or install additional signal heads)	All	Signal	Urban		735					d    635
	All	Signal	Urban							e    635
	Fatal/Injury	Signal	Urban		335
	PDO	Signal	Urban		935
Improve visibility of signal heads (install two red displays in each head)	All	Signal			916		3616
Install larger signal lenses (12 inch)	All	Signal			1116		4628
	All	Signal	Urban		2433
	Fatal/Injury	Signal	Urban		1633
Install signal backplates only	All	Signal			1316		5016
Install signal backplates (or visors)	All	Signal					209
Install signals	All	No Signal			3316	3826				j    5026
	All	No Signal	Rural Urban Urban		389		749	229		c 229	<5,000/lane (Total)
	All	No Signal			209		439	209		c    209	>5,000/lane (Total)
	All	No Signal	Rural		1526
	Fatal	No Signal			3826
	Fatal/Injury	Stop	Urban	3-Leg	14(32)21		34(45)21	-50(51)21			11,750-42,000 / 900-4,000
	Fatal/Injury	Stop	Urban	4-Leg	23(22)21		67(20)21	-38(39)21			12,650-22,400 / 2,400-3,625
	PDO	No Signal			-1526
Install signals (temporary)	Fatal/Injury	No Signal					399		509
	PDO	No Signal				119	739			a    839
Install signals (to have one over each approach lane)	All	Undefined	All				468
Remove unwarranted signals	All	Signal	Urban		2411		2411	2911		d    3011
	All	Signal	Urban							e    2211
	All	Signal	Urban							g    3111
	Fatal/Injury	Signal	Urban		5311
	PDO	Signal	Urban		2411
Replace signal lenses with optical lenses	All	Signal			1716	109	109	109		a    209
COMBINATION SIGNAL AND OTHER COUNTER MEASURES
Install left-turn lane and add turn phase	All	Signal			5816
Install signals and add channelization	PDO	No Signal				249	639			a    279
	Fatal/Injury	No Signal					679		549	b    359

Table 2: Geometric Countermeasures

Countermeasure(s)	Crash Severity	Control	Area Type	Configuration	All Crashes	Left-turn Crashes	Rt-angle Crashes	Rear-end Crashes	Sideswipe Crashes	Other Crashes	Major/Minor Daily Traffic Volume (vehicles/day)
LEFT TURN COUNTERMEASURES
Add indirect left-turn treatments to minimize conflicts	All	Stop			18(8)38						>34,000
	All	Stop			-24(35)38						>34,000/4 lanes
	All	Stop			26(8)38						>34,000/6 lanes
	All	Stop			24(63)38						>34,000/8 lanes
	Fatal/Injur y	Stop			27(12)38						>34,000
	PDO	Stop			6(11)38						>34,000
Create directional median openings to allow left-turns and u-turns	All	Signal			5131
Install left-turn lane	All	Signal	Rural	3-Leg	1514						4,200-26,000/ 1,300-11,400
	All	Signal	Rural	4-Leg (1 app )	1814						4,200-26,000/ 1,300-11,400
	All	Signal	Urban	3-Leg	714						4,600-55,100/ 100-26,000
	All	Signal	Urban	4-Leg (1 app )	10(10)14	1311					4,600-55,100/ 100-26,000
	All	Signal	Urban	4-Leg (2 apps )	19(13)14	2411					4,600-55,100/ 100-26,000
	All	Stop	Rural	3-Leg	44(6)14	6211					1,100-32,400/ 25-11,800
	All	Stop	Rural	4-Leg(1 app)	28(3)14	3711					1,100-32,400/ 25-11,800
	All	Stop	Rural	4-Leg (2 apps )	48(3)14	6011					1,100-32,400/ 25-11,800
	All	Stop	Urban	3-Leg	33(12)14						1,520-40,600/ 80-8,000
	All	Stop	Urban	4-Leg (1 app)	27(3)14	2611					1,520-40,600/ 80-8,000
	All	Stop	Urban	4-Leg (2 apps)	47(4)14	4511					1,520-40,600/ 80-8,000
	Fatal/Injury	Signal	Urban	4-Leg (1 app)	9(1)14						4,600-55,100/ 100-26,000
	Fatal/Injury	Signal	Urban	4-Leg (2 apps)	17(2)14						4,600-55,100/ 100-26,000
	Fatal/Injury	Stop	Rural	3-Leg	55(8)14						1,100-32,400/ 25-11,800
	Fatal/Injury	Stop	Rural	4-Leg (1 app)	35(3)14						1,100-32,400/ 25-11,800
	Fatal/Injury	Stop	Rural	4-Leg (2 apps)	58(4)14						1,100-32,400/ 25-11,800
	Fatal/Injury	Stop	Urban	4-Leg (1 app)	29(4)14						1,520-40,600/ 80-8,000
	Fatal/Injury	Stop	Urban	4-Leg (2 apps)	50(6)14						1,520-40,600/ 80-8,000
Install left-turn lane (double)	Fatal/Injur y	Undefined				479	209	299	509	a    759
	PDO	Undefined				719	89	329		b    139
Install left-turn lane (painted separation)	All	Undefined			509	579	629	549		c    549	<5,000/lane (Total)
	All	Undefined				359	499	399		c    399	>5,000/lane (Total)
	Fatal/Injury	Undefined	Mostly rural	3-Leg	22(14)6						5,000-15,000
	Fatal/Injury	Undefined	Mostly rural	4-Leg	-28(27)6						5,000-15,000
	PDO	Undefined	Mostly rural	3-Leg	20(19)6						5,000-15,000
	PDO	Undefined	Mostly rural	4-Leg	26(12)6						5,000-15,000
Install left-turn lane (physical channelization)	All	No Signal		4-Leg (2 apps )	4216
	All	No Signal	Rural	3-Leg	4416
Install left-turn lane (physical channelization)	All	No Signal	Rural	4-Leg (1 app)	28 16
	All	No Signal	Urban	3-Leg	33 16
	All	No Signal	Urban	4-Leg (1 app)	27 16
	All	Undefined			51 9	24 9	68 9	50 9		c    509	< 5,000/lane (Total)
	All	Undefined			19 9	24 9	55 9	28 9		c    289	> 5,000/lane (Total)
	Fatal/Injury	Undefined				50 9	58 9	11 9
	Fatal/Injury	Undefined	Rural	3-Leg	27(13) 6						5,000-15,000
	Fatal/Injury	Undefined	Rural	4-Leg	4(12) 6						5,000-15,000
	PDO	Undefined					54 9	56 9		b    50 9
	PDO	Undefined	Rural	3-Leg	-20(23) 6						5,000-15,000
	PDO	Undefined	Rural	4-Leg	16(22) 6						5,000-15,000
Install left-turn lane (signal has left-turn phase)	All	Signal			31 16	44 16
	All	Signal		4-Leg						h    73 25
	All	Signal		4-Leg						i    66 25
Install left-turn lane (signal has no turn phase)	All	Signal			23 16	50 16
Install left-turn lane (with channelization and existing left-turn phase)	All	Signal			35 9
Install left-turn lane (with channelization and no left-turn phase)	All	Undefined			15 9
Install left-turn lane (within existing curbs)	All	Signal			26 16	66 16
Install left-turn refuge within flush median	All	Undefined			24 9			44 9		c    44 9	<5,000/lane (Total)
	All	Undefined			44 9	77 9		40 9	52 9	a    52 9	>5,000/lane (Total)
	All	Undefined								c    40 9	>5,000/lane (Total)
Remove left-turn lane	All	Signal	Rural	3-Leg	-18 3
	All	Signal	Rural	4-Leg (1 app)	-22 3
	All	Signal	Rural	4-Leg (2 apps )	-49 3
	All	Signal	Urban	3-Leg	-8 3
	All	Signal	Urban	4-Leg (1 app)	-11 3
	All	Signal	Urban	4-Leg (2 apps )	-23 3
	All	Stop	Urban	3-Leg	-49 3
	All	Stop	Urban	4-Leg (1 app)	-37 3
	All	Stop	Urban	4-Leg (2 apps )	-88 3
	Fatal/Injury	Signal	Rural	3-Leg	-16 3
	Fatal/Injury	Signal	Rural	4-Leg (1 app)	-21 3
	Fatal/Injury	Signal	Rural	4-Leg (2 apps )	-45 3
	Fatal/Injury	Signal	Urban	3-Leg	-6 3
	Fatal/Injury	Signal	Urban	4-Leg (1 app)	-10 3
	Fatal/Injury	Signal	Urban	4-Leg (2 apps )	-21 3
	Fatal/Injury	Stop	Urban	3-Leg	-53 3
	Fatal/Injury	Stop	Urban	4-Leg (1 app)	-41 3
	Fatal/Injury	Stop	Urban	4-Leg (2 apps )	-98 3
RIGHT TURN COUNTERMEASURES
Increase length of right-turn lane	Fatal/Injury	All	All	All	15 37
Install right-turn lane	All	Signal	All	4-Leg (1 app )	4(2)14						4,200-55,100/ 100-26,000
Install right-turn lane	All	Stop	All	4-Leg (1 app)	14(5)14						1,100-40,600/ 25-11,800
	All	Signal	All	4-Leg (2 apps )	8(3)14						4,200-55,100/ 100-26,000
	All	Stop	All	4-Leg (2 apps )	26(7)14						1,100-40,600/ 25-11,800
	Fatal/Injury	Signal	All	4-Leg (1 app )	9(3)14						4,200-55,100 / 100-26,000
	Fatal/Injury	Stop	All	4-Leg (1 app )	23(7)14						1,100-40,600/ 25-11,800
	All	Undefined					509	659	209	j    539
Install right-turn lane (painted separation)	Fatal/Injury	All	All	All	3037
Install left-turn lane (physical channelization)	Fatal/Injury	All	All	All	3537
OTHER GEOMETRIC COUNTERMEASURES
Convert four-leg to two T-intersections	Fatal/Injury	Undefined	Urban	4-Leg	33(6)6						<70%/>30%
	Fatal/Injury	Undefined	Urban	4-Leg	-35(15)6						>85%/<15%
	Fatal/Injury	Undefined	Urban	4-Leg	25(5)6						70-85%/15-30%
	PDO	Undefined	Urban	4-Leg	10(5)6						<70%/>30%
	PDO	Undefined	Urban	4-Leg	-15(6)6						>85%/<15%
Convert intersection to roundabout	All	All	All		35(3)32
	All	Signal	All		48(5)32
	All	Stop (2-way )	All		44(4)32
	All	Stop (4-way )	All		-3(15)32
	All	Stop (2-way )	Rural	1-Lane	72(4)32
	All	Signal	Urban		1(12)32
	All	Stop (2-way )	Urban		31(6)32
	All	Stop (2-way )	Urban	1-Lane	56(6)32
	All	Signal	Urban	2-Lanes	67(4)32
	All	Stop (2-way )	Urban	2-Lanes	18(8)32
	Fatal/Injury	All	All		76(3)32
	Fatal/Injury	Signal	All		78(6)32
	Fatal/Injury	Stop (2-way )	All		82(3)32
	Fatal/Injury	Stop (4-way )	All		-28(41)32
	Fatal/Injury	Stop (2-way )	Rural	1-Lane	87(3)32
	Fatal/Injury	Signal	Urban		60(12)32
	Fatal/Injury	Stop (2-way )	Urban		74(6)32
	Fatal/Injury	Stop (2-way )	Urban	1-Lane	78(7)32
	Fatal/Injury	Stop (2-way )	Urban	2-Lanes	72(9)32
Improve sight distance in 1 quadrant	All	Stop/Yield (2-way )	Rural	4-Leg	513
Improve sight distance in 2 quadrants	All	Stop/Yield (2-way )	Rural	4-Leg	913
Improve sight distance in 3 quadrants	All	Stop/Yield (2-way )	Rural	4-Leg	1313
Improve sight distance in 4 quadrants	All	Stop/Yield (2-way )	Rural	4-Leg	1713
	All	Signal	Rural	4-Leg	013
Increase median width by 3 ft	All	Stop	Rural	4-Leg						f   4(1)12
	All	Stop	Urban	3-Leg						f -3(1)12
	All	Signal	Urban	4-Leg						f -3(1)12
Increase median width by 3 ft	All	Stop	Urban	4-Leg						f -6(1)12
	Fatal/Injury	Stop	Rural	4-Leg						f 4(1)12
	Fatal/Injury	Signal	Urban	4-Leg						f -3(1)12
	Fatal/Injury	Stop	Urban	4-Leg						f -5(1)12
Increase pedestrian storage area at corner	Fatal/Injury	Undefine d			-12(126)2
Install median	All	Stop	Rural		273
Install median islands (painted) on major road approaches	Fatal/Injury	All	All	All	1537
Install median islands (physical) on major road approaches	Fatal/Injury	All	All	All	2537
Install raised median	All	No Signal			2516
Install raised median (marked crosswalk)	All	No Signal								r    4638
Install raised median (unmarked crosswalk)	All	No Signal								r    3938
Install refuge islands	All	Undefined								r    5616
Install splitter islands on minor road approaches	Fatal/Injury	All	All	3-Leg	4537
	Fatal/Injury	All	All	4-Leg	4037
	Fatal/Injury	All	All	All	4037
	Fatal/Injury	All	Rural	All	3537
	Fatal/Injury	All	Urban	All	4037
Install turn and bypass lanes	All	Stop	Rural		5(10)29
	Injury	Undefined		3-Leg		369	249	189
	PDO	Undefined		3-Leg		289	539	219	309	a    139
	PDO	Undefined		3-Leg						b    409

Table 3: Signs/Markings/Operational Countermeasures

Countermeasure(s)	Crash Severity	Control	Area Type	Configuration	All Crashes	Left-turn Crashes	Rt-angle Crashes	Rear-end Crashes	Sideswipe Crashes	Other Crashes	Major/Minor Daily Traffic Volume (vehicles/day)
SIGNS
Install double stop signs	All	No Signal			1116		55(52)28
Install flashing beacons as advance warning	All	Undefined		3-Leg	709
	All	Undefined		4-Leg	399
	All	Signal			2716
	Fatal/Injury	Undefined				679	739
	PDO	Undefined				799	629
	All	Signal		4-Leg			6225	3625
Install larger stop signs	All	Stop			199						> 5,000/lane (Total)
Install pedestrian signing	All	Undefined			49
	All	Undefined								r    159
Install advance warning signs (positive guidance)	All	Signal			2216		35(1)28
	All	Undefined	Urban		309
	All	Undefined	Rural		409
Provide overhead lane-use signs	All	Undefined			1031
	All	Undefined			2031
PAVEMENT MARKINGS/MODIFICATIONS
Add centerline and move STOP bar to extended curb lines	All	No Signal			2916		2416
Add centerline and move STOP bar to extended curb lines, double stop signs	All	No Signal			916
Add centerline and STOP bar, replace 24-inch with 30-inch stop signs	All	No Signal					67(11)28
Improve pavement friction (groove)	All	Undefined			2516					p    5916
Improve/install pedestrian crossing	All	Undefined								r    259
Install pedestrian crossing	Fatal/Injury	Undefined	Rural							r    6024
Install pedestrian crossing (raised)	All	Undefined			30(67)2
	Fatal/Injury	Undefined			36(54)2
Install raised intersection	Fatal/Injury	Undefined		4-Leg	-56
	PDO	Undefined		4-Leg	-136
Install raised pavement markers	All	Undefined			1016					p    2516
	All	Undefined								q    3316
Install STOP bars (pedestrian crosswalk)	All	Signal			1816
Install STOP bars (STOP bar on minor road approaches, with short segments of centerline)	All	Undefined			1916
	All	Undefined					4716
Install transverse pavement markings	All	Undefined			189
	Fatal/Injury	Stop								k 57(8)10
	Serious Injury	Stop								k 74(13)10
	Slight Injury	Stop								k 52(11)10
	All	Stop								l 66(8)10
	All	Stop								k 48(14)10
	All	Stop								n 45(15)10
	All	Stop								o 68(11)10
Install transverse rumble strips on approaches	All	Stop			289
	All	Undefined						909
	All	No Signal	Rural		3516
Mark pavement with supplementary warning messages	All	No Signal			616
	Stop	Urban				30(66)28
Provide bicycle box (advance stop bar to leave dedicated space for cyclists)	All	Signal								t    3531
Provide bicycle lanes	All	Undefined								t    3631
Resurface pavement	All	Undefined			3316					p    4716
REGULATORY
Convert STOP control to Yield control	All	Stop	Urban	4-Leg	-127(70)22
	All	Stop	All		-13711
Convert to all-way STOP control (from 2-way control)	Fatal/Injury	Stop	Urban		71(6)18
	All	Stop	Urban			20(52)18	72(3)18	13(13)18
Convert two-way to one-way roadway	All	Undefined			269
Convert Yield control to STOP contro	All	No Signal			2916		916
Install no left-turn and no u-turn signs	All	Undefined	Urban		62(6)4	59(5)4					19,435-42,000 (Total)
Permit right-turn-on-red	All	Signal			-7(1)2					r -43(24)2
	Fatal/Injury	Signal								j -60(5)6
	PDO	Signal								j -10(1)6
Prohibit left turns	All	Undefined			459	909		309		r     109
Prohibit right-turn-on-red	All	Signal			341		309	209	209	b     309
Prohibit turns	All	Undefined	All							s     451
Restrict parking near intersections (to off-street)	All	Undefined			4916					r     309
LIGHTING
Install lighting	All	Signal			3031					d    5031
	Fatal/Injury	Signal			1731
	All	No Signal			4716
OPERATIONAL
Convert STOP control (2-way) l to signal contro	All	Stop			289		749
	Injury	Stop			439
Convert STOP control (2-way) to signal control and install left-turn lane	All	Stop			369		749	89
	Injury	Stop			539
Increase enforcement related to motorist yielding in marked crosswalks combined with a public education campaign	All	Undefined								r   2342
Install angled median crosswalk	All	Undefined			1216
Install beacon (flashing) at intersection	All	Undefined	All		301
Install cameras to detect red-light running	All	Signal					25(3)27	-15(3)27			52,625-109,067/ 12,562-33,679
	All	Signal			-12(5)23						17,000-78,000
	All	Signal	Urban			45(6)36
	Fatal/Injury	Signal			-14(9)23						17,000-78,000
	Fatal/Injury	Signal					16(6)27	-24(12)27			52,625-109,067/ 12,562-33,679
Install flashing red/yellow signal (MUTCD: intersection control beacon)	All	No Signal			259		359				< 5,000/lane (Total)
	All	No Signal			269		369				> 5,000/lane (Total)
	All	No Signal								a    509
	Fatal/Injury	No Signal			509
Install pedestrian crossing (signed and marked with curb ramps and extensions)	All	No Signal			3716
Install pedestrian overpass/ underpass	All	No Signal								r   1316
Install stop signs at alternate intersections in residential areas	All	Stop	Urban		5034
	Fatal/Injury	Stop	Urban		6734

References

1. Agent, K. R., Stamatiadis, N., and Jones, S., “Development of Accident Reduction Factors.” KTC-96-13, Kentucky Transportation Cabinet, (1996)
2. Bahar, G., Parkhill, M., Hauer, E., Council, F., Persaud, B., Zegeer, C., Elvik, R., Smiley, A., and Scott, B. “Prepare Parts I and II of a Highway Safety Manual: Knowledge Base for Part II”. Unpublished material from NCHRP Project 17-27, (May 2007)
3. Bonneson, J., Zimmerman, K., and Fitzpatrick, K., “Roadway Safety Design Synthesis.”Texas Transportation Institute for Texas DOT, (2005)
4. Brich, S. C. and Cottrell Jr, B. H., “Guidelines for the Use of No U-Turn and No-Left Turn Signs.”VTRC 95-R5, Richmond, Virginia Department of Transportation, (1994)
5. De Brabander, B. and Vereeck, L., “Safety Effects of Roundabouts in Flanders: Signal type, speed limits and vulnerable road users.” AAP-1407, Elsevier Science, (2006)
6. Elvik, R. and Vaa, T., “Handbook of Road Safety Measures.” Oxford, United Kingdom, Elsevier, (2004)
7. Felipe, E., Mitic, D., and Zein, S. R., “Safety Benefits of Additional Primary Signal Heads.”Vancouver, B.C., Insurance Corporation of British Columbia; G.D. Hamilton Associates, (1998)
8. FHWA and Institute of Transportation Engineers, “Making Intersections Safer: A Toolbox of Engineering Countermeasures to Reduce Red-Light Running.” FHWA/TX-03/4027-2, Texas Transportation Institute, (2002)
9. Gan, A., Shen, J., and Rodriguez, A., “Update of Florida Crash Reduction Factors and Countermeasures to Improve the Development of District Safety Improvement Projects.” Florida Department of Transportation, (2005)
10. Griffin, L. I. and Reinhardt, R. N., “A Review of Two Innovative Pavement Patterns that Have Been Developed to Reduce Traffic Speeds and Crashes.” Washington, D.C., AAA Foundation for Traffic Safety, (1996)
11. Harkey, D., Srinivasan, R., Zegeer, C., Persaud, B., Lyon, C., Eccles, K., Council, F. M., and McGee, H., “Crash Reduction Factors for Traffic Engineering and Intelligent Transportation System (ITS) Improvements: State of Knowledge Report.” Research Results Digest, Vol. 299, Transportation Research Board of the National Academies, (2005)
12. Harwood, D. W., Pietrucha, M. T., Wooldridge, M. D., Brydia, R. E., and Fitzpatrick, K., “NCHRP Report 375: Median Intersection Design.”Washington, D.C., Transportation Research Board, National Research Council, (1995)
13. Harwood, D. W., Council, F. M., Hauer, E., Hughes, W. E., and Vogt, A., “Prediction of the Expected Safety Performance of Rural Two-Lane Highways.” FHWA RD-99-207, McLean, Va., Federal Highway Administration, (2000)
14. Harwood, D. W., Bauer, K. M., Potts, I. B., Torbic, D. J., Richard, K. R., Kohlman Rabbani, E. R., Hauer, E., and Elefteriadou, L., “Safety Effectiveness of Intersection Left- and Right-Turn Lanes.” FHWA-RD-02-089, McLean, Va., Federal Highway Administration, (2002)
15. Hauer, E., “Left Turn Protection, Safety, Delay and Guidelines: A Literature Review.” www.roadsafetyresearch.com, (2004)
16. Institute of Transportation Engineers, “Toolbox of Countermeasures and Their Potential Effectiveness to Make Intersections Safer.” Briefing Sheet 8, ITE, FHWA, (2004)
17. Lee, J. C., Wortman, R. H., Hook, D. J., and Poppe, M. J., “Comparative Analysis of Leading and Lagging Left Turns.” Phoenix, Arizona Department of Transportation, (1991)
18. Lovell, J. and Hauer, E., “The Safety Effect of Conversion to All-Way Stop Control.”Transportation Research Record 1068, Washington, D.C., Transportation Research Board, National Research Council, (1986) pp. 103-107.
19. Lyon, C, Haq, A., Persaud, B. N., and Kodama, S. T. , “Development of Safety Performance Functions for Signalized Intersections in a Large Urban Area and Application to Evaluation of Left Turn Priority Treatment.” 2005 TRB 84th Annual Meeting: Compendium of Papers CD-ROM, Vol. TRB#05-2192, Washington, D.C., (2005)
20. Markowitz, F., Sciortino, S., Fleck, J.L., and Yee, B.M., “Pedestrian Countdown Signals: Experience with an Extensive Pilot Installation.” Institute of Transportation Engineers Journal, January 2006, pp. 43-48. Updated by Memorandum, Olea, R., “Collision changes 2002-2004 and countdown signals,” (February 7th, 2006)
21. McGee, H., Taori, S., and Persaud, B. N., “NCHRP Report 491: Crash Experience Warrant for Traffic Signals.”Washington, D.C., Transportation Research Board, National Research Council, (2003)
22. McGee, H. W. and Blankenship, M. R., “NCHRP Report 320: Guidelines for Converting Stop to Yield Control at Intersections.”Washington, D.C., Transportation Research Board, National Research Council, (1989)
23. Miller, J. S., Khandelwal, R, and Garber, N. J., “Safety Impacts of Photo-Red Enforcement at Suburban Signalized Intersections: An Empirical Bayes Approach.”, Transportation Research Record, No. 1969, Washington, D.C., Transportation Research Board, National Research Council, (2006), pp. 27-34.
24. Montella, A., “Safety Reviews of Existing Roads: a Quantitative Safety Assessment Methodology.” 2005 TRB 84th Annual Meeting: Compendium of Papers CD-ROM, Vol. TRB#05-1295, Washington, D.C., (2005)
25. Morena, D. A., Wainwright, W. S., and Ranck, F., “Older Drivers at a Crossroads.” Public Roads, Vol. 70, No. 4, Washington, D.C., FHWA, (2007) pp. 6-15.
26. Pernia, J.C., Lu, J.J., Weng, M.X., Xie, X., and Yu, Z., “Development of Models to Quantify the Impacts of Signalization on Intersection Crashes.” Florida Department of Transportation, (2002).
27. Persaud, B., Council, F. M., Lyon, C., Eccles, K., and Griffith, M., “Multi-Jurisdictional Safety Evaluation of Red Light Cameras.”Transportation Research Record, No. 1922, Washington, D.C., Transportation Research Board, National Research Council, (2005) pp. 29 - 37.
28. Polanis, S. F., “Low-Cost Safety Improvements. Chapter 27, The Traffic Safety Toolbox: A Primer on Traffic Safety”, Washington, D.C., Institution of Transportation Engineers (1999) pp. 265-272
29. Preston, H. and Schoenecker, T., “Bypass Lane Safety, Operations, and Design Study.” MN/RC-2000-14, St. Paul, Minnesota Department of Transportation, (1999)
30. Retting, R. A., Chapline, J. F., and Williams, A. F., “Changes in Crash Risk Following Re-timing of Traffic Signal Change Intervals.” Accident Analysis and Prevention, Vol. 34, No. 2, Oxford, N.Y., Pergamon Press, (2002) pp. 215-220.
31. Rodegerdts, L. A., Nevers, B., and Robinson, B., “Signalized Intersections: Informational Guide.” FHWA-HRT-04-091, (2004)
32. Rodegerdts, L. A., Blogg, M., Wemple, E., Myers, E., Kyte, M., Dixon, M., List, G., Flannery, A., Troutbeck, R., Brilon, W., Wu, N., Persaud, B., Lyon, C., Harkey, D., and Carter, E. C., “Roundabouts in the United States.” NCHRP Report 572, Washington, D.C., Transportation Research Board of the National Academies, (2007)
33. Sayed, T., Leur, P. , and Pump, J., “Safety Impact of Increased Traffic Signal Backboards Conspicuity.” 2005 TRB 84th Annual Meeting: Compendium of Papers CD-ROM, Vol. TRB#05-16, Washington, D.C., (2005)
34. Sayed, T., El-Basyouny, K., and Pump, J., “Safety Evaluation of Stop Sign In-Fill Program.”Transportation Research Record 1953, Washington, D.C., Transportation Research Board, National Research Council, (2006) pp. 201-210.
35. Sayed, T., El Esawey, M., and Pump, J., “Evaluating the Safety Impacts of Improving Signal Visibility at Urban Signalized Intersections.” 2007 TRB 86th Annual Meeting: Compendium of Papers CD-ROM, Vol. TRB#07-135, Washington, D.C., (2007)
36. Shin, K. and Washington, S., “The Impact of Red Light Cameras on Safety in Arizona.” 2006 TRB 85th Annual Meeting: Compendium of Papers CD-ROM, Vol. TRB#06-1514, Washington, D.C., (2006)
37. Turner, B., “Crash reduction estimates for road safety treatments.”, Vermont, Australia, ARRB Group, (2007)
38. Xu, L., “Right Turns Followed by U-Turns Versus Direct Left Turns: A Comparison of Safety Issues.” ITE Journal, Vol. 71, No. 11, Washington, D.C., Institute of Transportation Engineers, (2001) pp. 36-43.
39. Zegeer, C., Stewart, R., Huang, H., and Lagerwey, P., “Safety Effects of Marked vs. Unmarked Crosswalks at Uncontrolled Locations: Executive Summary and Recommended Guidelines,” FHWA-RD-01-075, (March 2002)
40. Zimmerman, K. and Bonneson, J., “In-Service Evaluation of the Detection-Control System for Isolated High-Speed Intersections.” 2006 TRB 85th Annual Meeting: Compendium of Papers CD-ROM, Vol. TRB#06-1252, Washington, D.C., (2006)

    Updated August 2008

41. Harkey, D., Srinivasan, R., Baek, J., Council, F. M., Eccles, K., Lefler, N., Gross, F., Persaud, B., Lyon, C., Hauer, E., and Bonneson, J. A., “Crash Reduction Factors for Traffic Engineering and ITS Improvements,” NCHRP Report No. 617, (2008)
42. Van Houten, R. and Malenfant, J. E., “Effects of a Driver Enforcement Program on Yielding to Pedestrians,” Journal of Applied Behavioral Analysis, No. 37, (2004) pp. 351 - 363.