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Screening Needs for Roadway Lighting. April 15, 2003. Motivation. About 40,000 fatalities due to traffic crashes per year in the U.S. Night crash rate is three times higher than day crash rate

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motivation
Motivation
  • About 40,000 fatalities due to traffic crashes per year in the U.S.
  • Night crash rate is three times higher than day crash rate
  • About 15,000 lives could have been saved if nighttime crash rate could have been reduced to daytime crash rate in 1993 only
motivation cont
Motivation (cont.)
  • Causes of higher nighttime crash rate
    • Low light level affecting visual capabilities
    • Increased alcohol usage
    • Fatigue
    • Over-representation of young drivers
    • Nighttime fatality rate three times day fatality rate

Source: CIE (1992)

motivation cont4
Motivation (cont.)
  • Potential positive impacts of fixed roadway lighting
    • Reduction of nighttime accident rate
    • Increased safety for pedestrians
    • Facilitation of traffic flow
    • Inspiration of community growth
    • Aid to police protection
    • Promotion of business

Source: AASHTO (1984)

motivation cont5
Motivation (cont.)
  • Potential negative impacts of fixed roadway lighting
    • Glare
    • Light pollution
    • Light reflected form roads causing sky to glow
    • Aesthetic effect caused by clutter
    • Energy waste

Source: Shaflik (1997)

outline
Outline
  • Background
  • Methodology development
    • Overview of the screening method
    • Exposure assessment
    • Site-parameters assessment
  • Data analysis to support the screening method
  • Example
  • Summary of contributions
background8
Background
  • Fixed roadway lighting - Wilken et al. (2001), Kramer (1999, 2001), ANSI (2000), Cottrell (2000), Edwards (2000), IES (2000), Walton (2000), Watson (2000), Gransberg (1998), Sandhu (1992), APWA (1986), Janoff (1984, 1986).
  • Safety benefits of lighting - Dewar and Olson (2002), Griffith (1994), Box (1989, 1972), Trivedi (1988), Janoff (1984, 1986), and Marshall (1970)).
  • Support to site-parameters assessment - Dewar and Olson (2002), Donnell et al. (2001), Fitzpatrick et al. (2000), Garber (2000), Hatch (1999), Rumar (1998), Blower and Campbell (1998), Griffith (1994), FHWA (1993), Ohta et al. (1991), Glennon (1987), and NCHRP (1974).
background cont
Background (cont.)
  • Roadway lighting design and engineering - Staplin et al. (2001), Khan et al. (2000), Garber (2000), Couret (1999), Crawford (1999), Shaflik (1997), Jefferson (1994), FHWA (1993), and Janoff and Zlotnick (1985).
  • Traffic engineering - Garber and Hoel (2002), Melcher et al. (2001), Garber (2000), Lyon and Nguyen (1999), Hauer (1996), Tarko, Kumares and Farooq (1996), Judycki (1994), Higle and Witkowski (1988), and Persaud, Turner and Colson (1988).
  • Risk assessment and management methods - Bedford and Cooke (2001), Koller (2000), Vose (2000), Haimes (1998), and Kumamoto and Henley (1996).
background cont10
Background (cont.)
  • Uncertainty propagation and fuzzy arithmetic - Kaufmann and Gupta (1991), and Morgan and Henrion (1990).
  • Multi-criteria decision analysis - Pomerol and Barba-Romero (2000), Gal, Stewart and Hanne (1999), Ballestero and Romero (1998), and Steur (1986).
  • Benefit-to-cost methods - IADOT (2001), NYMTC (2001), McFarland and Walton (2000), Janoff and McCunney (1979).
  • Existing screening methods - NCHRP (1974), and AASHTO (1984).
background cont11
Background (cont.)
  • Percentage reduction of nighttime crashes for before-and-after study of safety improvement via lighting

Source: CIE (1990)

background cont13
Background (cont.)

AASHTO screening method for Complete Interchange Lighting (CIL)

CIL-1 Traffic on crossroad

  • ADT > 10,000 urban conditions
  • ADT > 8,000 suburban conditions
  • ADT > 5,000 rural conditions

CIL-2 When existing substantial commercial or industrial development, which are lighted at night, is located in immediate vicinity of the interchange

Where the crossroad approach legs are lighted for ½ mile or more on each side of the interchange

Source: AASHTO (1984)

background cont14
Background (cont.)
  • NCHRP warrants
    • Weighted score method
    • Burdensome level of detail
    • Diminished relevance since 1970’s

Source: NCHRP (1974)

methodology development
Methodology Development

Overview of screening method

slide16

Overview of Screening Method

  • Context of the screening method
    • Full evaluation is costly
    • Selection of needs saves resources
methodology development17
Methodology Development

Exposure assessment

methodology development24
Methodology Development

Site-parameters assessment

slide25

Site Parameters Assessment

  • Demonstration that roadway lighting is the best safety enhancement available
site parameters assessment cont29
Site Parameters Assessment (cont.)
  • Support to site-parameters assessment factors
  • Example curvature and grade
    • A. Overview - brief description of the factor
    • B. Technical explanation
      • The maximal curvature affects the anticipation of changes in road geometry
      • The grade of the road alters perception of speed
    • C. Empirical evidence
    • D. Specific countermeasures – evidence that fixed roadway lighting or any available technology be uniquely effective
      • Lighting on a curve can reduce the effect of glare from the headlamps of an oncoming car
methodology development30
Methodology Development

Exposure assessment

Site-parameters assessment

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unlighted nodes study
Unlighted Nodes Study
  • Study of unlighted nodes in Richmond District
  • Nodes are landmarks, or milestones of the roadway
  • Input data:
    • All crashes from 1/1/1997 through 12/31/2001
    • 122,126crashes (total)
    • 83,467 daylight
    • 38,659 nighttime
    • 12,163nighttime, unlighted

Source: Rasmussen and Jones (2002)

unlighted nodes study cont34
Unlighted Nodes Study (cont.)
  • Analysis of the 37 nodes with the highest number of crashes
    • Sample of data
unlighted nodes study cont35
Unlighted Nodes Study (cont.)
  • Selection of 37 unlighted nodes with highest number of crashes
data analysis to support the screening method36
Data Analysis to Support the Screening Method

Unlighted two-mile sections study

unlighted two mile sections study
Unlighted Two-Mile Sections Study
  • Study of a selection of unlighted two-mile sections in Richmond, Northern Virginia and Hampton Roads districts
  • Night and day crashes on the 50 two-mile sections considered for a six years period from 01/01/96 to 12/31/01
unlighted two mile sections study cont39
Unlighted Two-Mile Sections Study (cont.)
  • Indirect night-to-day crash rate ratio estimation for all three regions
data analysis to support the screening method41
Data Analysis to Support the Screening Method

Unlighted half-mile sections study

data analysis cont
Data Analysis (cont.)

Summary of all unlighted nodes and unlighted two-mile sections

example45
Example
  • Intersection of Route 460 and Interstate 85 in Richmond District

Source: Bridewell (2001)

example cont
Example (cont.)

Exposure assessment for Rt. 460 and I-85

slide47

Example (cont.)

Site-parameters assessment for Rt. 460 and I-85

example cont48
Example (cont.)
  • Outcome of the screening method is “Marginal”
    • Exposure assessment: “Marginal”
    • Site parameters : “Marginal”
      • 6 “Low” and 2 “Moderate”
  • NCHRP original score was 45.5 over a warranting threshold of 75.0
    • Project was rejected by the NCHRP screening method
summary of contributions50
Summary of Contributions
  • Exposure assessment
    • Application of benefit-cost analysis, specialization of exogenous parameters, and interval arithmetic
  • Site parameters assessment
    • Set of eight design and engineering factors based on literature, scenarios analysis, engineers and experts
    • Narratives support the eight factors
  • Extensive regional study of unlighted crashes
  • Indirect night-to-day crash rate estimation method
    • Stratification by ADT, posted speed and lane configuration
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