Traffic Safety

How is traffic safety measured?

Crashes; not always adequate due to rareness, and does not emphasize human toll

What are the letters of the traffic injury scale?

KABCO

What does K mean on the KABCO scale?

Fatality

What does A mean?

Incapacitating injury like an amputation

What does B mean on the KABCO scale?

The victim has few injuries such as cuts and scrapes

What does C mean on the KABCO Scale?

There is possible injury but on a lesser scale

What does O mean on the KABCO scale?

There was no injury

Average economic costs by Injury severity

pure economic costs (medical,lost wages)

Average comprehensive cost by injury severity

includes estimate of lost quality of life

Surrogate Measures of Traffic Safety

* Number of near misses, evidence of unreported crashes, safety belt use, number of dui arrests

What is a near miss event

Potential hazard or incident where no property damage or injury occurred, but where given a slight shift in time or position, damage or injury easily could have occurred.

Four types of vehicle crash

Roll over, side swipe, head on, and rear end

Why did crashes increase in 2020?

COVID. people started driving faster since there was no cars on the road, and more likely to drive drunk (alcohol sales increased)

What are reasons for general fatality decline in crashes since the 1960s?

Seatlbelt usage, airbags, improve EMS, national speed limit

National Highway Safety Act 1966

* First major effort to improve highway safety at the federal level
* Accelerated highway safety programs in each state
* Increased highway safety research
* Requires stated to develop and maintain a highway safety program

Highway Safety Act of 1973

➢Established categorical funding for several safety improvement program areas: ▪Rail-highway grade crossing; ▪Pavement marking demonstration programs; ▪High-hazard locations; ▪Roadside obstacle elimination

4 E’s of Traffic Safety

Engineering, Education, Enforcement, and Emergency Medical services

Engineering in Traffic Safety

Safey oriented design, signal timing, pavement markings, signages

Education in Traffic safety

* Driver Training, Public education schools and camps

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Enformcement in Traffic Safety

Enforce speed, and traffic laws. DUI Checkpoints

EMS in traffic safety

\-preemption, incident clearence, and special lanes

SHSP (strategic hihgway safety plan)

major component of the highway safet imporvement porgram (HSIP)

* SHSP must be data-drive, developed in collaboration with a broad range of stakeholders, and address 4 e’s of highway safety

Highway Safety Improvememt Porgram

\-core Federal-aid program with the purpose to achieve a significant reduction in traffic fatalities and serious injuries on all public roads, including non-State-owned roads consists of the strategic hihgway safety plan

FAST ACT 2021

2021 bi-partisan infrastructure bill includes over $500 million for the Strengthening Mobility and Revolutionizing Transportation (SMART) program. ➢The SMART program will support transportation studies that implement advanced transportation technologies and innovative solutions (Act, 2021)

Fast Act 2015

Fixing America’s Surface Transportation (FAST) Act, enacted December 4, 2015 ▪ Intended to identify emerging safety needs ▪ Encourages states to apply for grant dollars to promote safety for bicyclists, pedestrians, and other non-motorized users ▪ Incorporates safety measures related to the transportation of hazardous materials ▪ Improves NHTSA’s ability to recall unsafe vehicles and increases maximum civil penalty against auto makers for safety-related defects

MAP- 21 (2012)

➢Moving Ahead for Progress in the 21st Century (MAP-21), enacted June 29, 2012 ➢Established a performance-based Federal program ▪ Added requirement for regular update of the strategic highway safety plan ▪ Retained set-aside for rail-highway grade crossings ▪ Secretary established measures and States set targets for number of injuries and fatalities (and number per VMT) ▪ Strengthened link between HSIP and NHTSA programs

Safetea-LU

Safe, Accountable, Flexible, Efficient Transportation Equity Act – A legacy for Users (SAFETEA-LU), enacted October 31, 2009 ▪ Nearly doubled funds for infrastructure safety ▪ Allowed increased flexibility in program funding, and required a focus on results

TES-21 1998

Transportation Equity Act for the 21st Century (TEA21), enacted June 9, 1998 ➢Provided more focus by including “safety and security” as a transportation planning priority ➢Provided guidance on a wide range of planning, policy an safety issues affecting bicycling and walking

Railroad Highway grade safety program

Railway-Highway Grade Crossing Program ➢Intended to reduce number and severity of train collisions with vehicles and pedestrians ➢Typical projects include: ▪ Install/upgrade signing and markings at crossings ▪ Install/upgrade of active warning devices ▪ Crossing surface, sight distance or geometric improvements ▪ Grade separations

Hazard Elimination Program

Hazard Elimination Program ➢Provided funding for projects to mitigate or eliminate hazardous elements on public roads ➢Typical projects include: ▪ Intersection improvements; ▪ Pavement and shoulder widening; ▪ Crash cushion installation; ▪ Roadway alignment modification; and

Where should you write your code in R?

The source pane

What d use for an equal sign in R?

Vector Code

a<-c(1,2,3)

What is R?

* R is a language environment for statistical computing. It;s free and good for data analysis

Crash Data Collection and Management

Crash Data are originally collected either by law enforcement or self reported vehicle owners

What are crash reports?

\- collected at predetermined level, collected electronically or manually, database usually maintained by DOT and DMV

Who relies on crash reports?

Insurance companies, City Engineers, and researchers

Why is consistent reported state crash data important?

* problem identification, establish performance measures, and allocate resources

MUCC

Minimum, standardized data set for describing motor vehicle crashes and the vehicles, persons and environment involved.

Implementation is a collaboritive effor betweeh the FHWA and GHSA

What are some common crash reporting coding errors?

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Crash Location, Crash type

What are the three tables for crash data tables?

* Table 1: Crash (time,location,circumstance)m
* Table 2: Vehicle types
* Table 2: people (driver passenger, age, gender)

Where are safety data used for transportation safety?

* Safety plans
* Analysis: Network Sceening, Prioritization, Evaluation of COuntermeasures

What are the three data needs?

Crash Data, Roadway Data, Traffic Data

What is the name of the Manual for data?

MIRE: provides structure for roadway inventory data

Three Categories of MIRE Elements

Roadway segment descriptors (ex Shoulder descriptors)

Roadway Alignment Descriptors ( Horizantal Curve and Vertical Grade Data)

Roadway Junction Descriptors(Intersection)

MIRE FDE for SEgments

Route number, surface type, and AADT

What does AADT stand for?

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Average annual daily traffic

MIRE FDE for Intersections

AADT for each intersection road, Intersection Geometry, Intersection traffic control

MIRe FDE for interchanges

ROadway type at beginning of ramp. Interchange type, Type of government ownership

What is a collision diagram?

* 2d plan view representation of the crashes that have ovvured at a site within a fiven time period. It simplidies the visualization of crash patterns. Crash pattern will become more evident.

What are some collision diagram applications?

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Graphical representation of crashes occurring at an intersection

Assist in determining potential causes of crash and countermeasures

Condition Diagrams can contain

Roadway consitions (shoulders, light poles, telephone pholes, medians)

Land uses( school retain)

Pavement conditions ( potholes)

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What are pedestrian human factors that need to be considered?

Walking speed

Less visible that cars

Distracted walking/texting

More susceptible to injury

What are some reasonable values for perception reaction time?

Expected situations (1.5 seconds)

Unexpected Situtations (2.5 seconds)

What are some factors that would affect PRT?

* Distraction, Age, Imparment, expectancy

Men or Women? Who are more likely to be involved in fatal crashes?

Men

What are some problems with older drivers?

Drivers 65 and older have slower reaction times, visual acuity is poor, glare recovery is slow, contrast sensitivity is poor

Who do engineers design for?

the 80-90th percentile. We cans accomade the whole entire population because it woulf cost too much money

How can color blind people still drive?

Sign Shapes: octogan (stop), triangular (yield), rectangle (information)

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Pacement of traffic signal heads: Green on Bottomm red on top

Visual Search Definition

the ability to search the rapidly changing road scene to collect information

Movement in depth

the ability to estimate the speed of another vehicle by the rate of change of change of visual angle of the vehicle created by the eye

When is movmeent in depth important?

when switching lanes or to prevent rear ended collisions

Peripheral vision defintion

The ability to detect objects that are outside of the area of most accurate vision within the eye

Contrast Sensitivity

The ability to detect slight differences in luminance (brightness of light) between an object and its background

Considered more important than visual acuity ➢Impacts ability to see signs and objects in road (including pedestrians!)

Visual acuity

the ability to see details at a distance

What are the five aspects of vision according to the HSM?

Visual Acuity, contrast senditivity, peripheral vision, movement in depth, visual search

Example of a consisten roadway design?

* Freeways having no stops
* Pavement markings

Consistency in traffic control devices

* Green meand go red means stop.
* Standard road signs and shapes
* standarized signal heads

Uncommon design charateristics

* Roundabaouts, meteresd ramps, lanes narrowing

Why is driver expectancy important

* improving expectancy is key to reduce driver error, drivers are more likley to respond correctlly to familiar situations

Driver overloading examples

Too many signs = hard to read

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underloading example

not enough signs or speed limit posted

Ways of Providing Guidance Info

* Traffic Control Devices (signs, traffic signals, CMS)
* Roadway Enviornement ( placement of signs and other obstacles, sigh distances, roadway alignemnet)

What are the three driving tasks:

Control ( Basic: steering and speed control)

Guidance( Mid level : road path following and responding to changes in the road)

Navigation: ( highest level driving tasks, trip planning and route following)

Who plays the most important role in design?

The driver; must be abel to identify cues in sufficent time to respond approporetely

What is Perception reaction time

Is the time it takes for a driver to perceive a potential hazard on the roadway and respond by taking action,

Study Classifications

* Crash based studies
* Traffic operation based
* Enviromental based
* special studies

Crashed base study examples

Type.severity,time of day

Traffic Operations study

vOLUME SPEED AND GAP

Environmental based

Roadway inventory sudies, weather related, sight distance

Sight Distance studies

Can identify sight obstructions

skid resistance studies

mesure traction properties between tires and pavement. Can need to be studied under wet road conditions leading to accidents

SPECIAL STUDIES

SCHOOL SCROSSIN,RAILROAD, PEDESTRIAN

bIKE/PEDESTRIAN STUDIES

BIKE SPEEDS. VOLUME. SIGHT DISTANCE

Collisions at driveways

left turning vehicles--→ install median divider

Pedestrian Crashes

Pedestrian walking on roadway---→ install sidewalks

Fixed object crashes

objects near the road---→ protect object with guardrail

Headon collisions

roadway design inadequate--→ install median devider

rear end collisions SIGNALIZED

inadequete signal times---- > adjust yellow phase add all red

high speed----→ reduce speed limit

right angle collisoin unsignalized

restricted sight distance: remove obstructions

rear end unsignazlized

slippery surface: provide SLIPPERY WHEN WET SIGN

rIGHT ANGLE SIGNALIZED

iNADEQUATE SIGNAL TIMING: ADJUST YELLOW PHASE

lEFT TURN SIGNALIZED OR UNSIGNALIZED

RESTRICTED SIGHT DISTANCE ---→ REMOVE OBSTACLES

SIDESWIPE COLLISIONS

ROADWAY DESIGN BAD>>>>WIDEN LANES

What are the seven methods of network screening

Crash Frequency, Crash Rate, Frequency Rate, EPDO, Relative severity Index, Level of Service of safety, Critical Rate method

what is the purpose of network screening?

The purpose of network screening is to identify sites with potential for safety improvement: ▪ Sites experiencing high numbers of crashes that may be reduced through cost-effective countermeasures

Network scrreening process

1. Establish Focus
2. Identidy Reference Populations
3. Select performance measures
4. select screening methods
5. screen and evaluate results

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Establish focus

identify sites with potential to reduce crash severity/frequenct