1975 - accidentes and geometric designs - arr_44

7/23/2019 1975 - Accidentes and Geometric Designs - ARR_44

1/29

.

Report

No

44

D D

Accidents and Geometric

Design

C

J. oughton

I

r

.

1-l

11

)

> I I f

AUSTRALIAN

ROAD RESEARCH BOARD

~ j f .


2/29

~ E f ; : .APPLICATION

SUMMARY

~ ~ ustralian

oad

Research Board

THE

PURPOSE

OF THIS

REPORT

........................

THIS REPORT SHOULO

INTEREST

....................

AS A

CONSEQUENCE

OF THE

WORK REPORTED

THE

FOLLOWING ACTION s

RECOMMENDED .....................

RELATED CURRENT

ARAB

RESEARCH ..........................

CUT

OUT INFORMATION

RETRIEVAL

CARD ........

AUSTRALIAN ROAD RESEARCH BOARD

llllll\

llll\

1945

1. To describe the

value

and avai labi l i ty of

road

accident

and

road

inventory data

in

Australia.

2. To

d e s ~ r i b e

any relationship between accidents

and geometric design

elements

extracted from

a l i terature survey

of

reportedAustralian

and overseas

studies.

ARRB

TEC

NAASRA TEC

S

RAs

New Zeal arid Ministry of Transport

Geometric

Road Design Committee

Ro

STA

Department of

Motor Transport, N.S.W.

Highways Department, S.A.

That

a

detailed.analysis of the

Department of

Main

Roads, .N.S.W. fatal accident reports be

in i t ia ted

with

a view to

determining w ~ t h r

.

a quantifiable relationship between accidents

.and

geometric

design elements

is

determinable

from such a

data

source.

Project

97241

Analysis of

DMR fatal accident reports for

N.S.W. 1969

to

1971

ACCIDENT

ANO GEOMETRIC

DESIGN

KEYWORDS: Accidents,

geometric

design.alianment, de jree of

curvature, paveMent, gradient, s u p e r ~ l e v a t i o n t raff ic lane

A l i terature survey of reported Austral i an and

overseas

studies

and an assessment of the value

of

accident and inventory data

available

in Australia has been

undertaken with

a view to

deter-

mining the

relation

between various road design elements

(alignment, pavement width .. shoulder width, etc.) and accidents.

Only one data source, DMR fatal accident reports for N.5.W.,

was

found to bave

accident

details and road inventory data

already

matched. Results of

reported

Australian

and

overseas

studies

s ~ g g s t that

curves

of

radius less

than

450 m and grades above

4 per cent should be avoided.

Also,

that. in terms of

reducing

accident rates no benefit would

accrue

from widening lanes

beyond 3. 4 m

REFERENCE:

BOUGHTON C.J. (1975): Accident and

Geometric

Design.- ARR Report No. 44; Australian

Road Research.Board.


3/29

'

.\

:

. Acc.(oE.NTS AN D

~ . 0 ) . , E J R I C

.

1

DE. IG.N.

Projec t Nd 9 7 2 31 ' "

:

By

C J

Boughton

/ . '

B S

c .

t S

c .

. ..

Research

Sc fen t i s t

October

1975

Aust ra l ian Road Research Board

500

Burwood Road

. Vermont South

Vic to r ia

.

'

'

ARR Rep No 44

i..


4/29

The ARR series of reports was created by

the

Board to quickly, and economically,

reproduce th e =(>nclusions of road and road transj:>ort research subjects for

those

associated with road and road

transport

industry. Unlike

other

technical publications

produced by ~ h e A ~ s t r a l i a n Road R e ~ e a r c h Board,

ARR

e ~ ~ r t s are not reviewed

by

referees or ARR Members. Therefore.,

the

opinions expressed

by the authors do not

necessarily represent

those of the

Board.

Reference to, or reproducti9n of this report must include a precise reference

io

the

report.

NATIONAL

LIBRARY.

OF AUSTRALIA CARO NUMBER ANO ISBN

0

909996

81

4


5/29

BAC KGROUN D

MATERIAL

SURVEY

OF LITE RATURE

General

Alignment

Crossfal

l

Pavement width

Shoulder

Summary

ACCIDENT

AND

INVENTORY

DATA

FINDINGS

AND

RECOMMENDATIONS

APPENDIX A

CONTENTS

ARRB

questionnaire on accidents

and geometric design

REFERENCES

Page

1

1

2

.

....

4

8

10

11

13

15

19

20

20

23

( .


6/29

ARR

Repo r t

No. 44 1975

BACKGROUND

1. As part of

the NAASRA

Review of

Geometric

Road Design,

NAASRA

Traffic

Engineering

Committee TEC)

(20th

Meeting

1974)

requested

t ~ a t RRB

undertake a

study of accidents.

related ~ o

various

design

elements, comprising:

(a)

a l i tera ture survey of r ~ p o r t e d

~ u s l r a ~ i a n

and

o v e r s ~ a s

studies .

and

(b) an

assessment of the value of a ~ c i d e n t and

inventory data available

in Australia.

T h ~ ultimate aim is

to

determine the

relat ion between

varfous

desigh elements and accidents, thus

a ~

~ n d

(bl

f ~ r m

the

e s s ~ n t i a l

p r e l i m i n a r i e ~

M T ER I

L

2. I f only

reported

studies

are

to be considered then the

1

Review-.

1

of

Road Design in Relation to

Road

Safety

1

(Sinclair and

Knight.1973),

commi.ssioned by the Expe rt Group on

Road

Safety, is

o b v i o u ~ l y the place to s tar t . The document is a

review

of both

Australian ~ n d overseas publications available in 1971. Internal

or

departmental

reports

or

other

matter

not

accessible

to public

sources

were not include.d. Two publications, .the f i r s t by

Jorgensen ( 1966) and the second by the Highway

U s ~ r s

Federati

11

for Safety and Mobility HUFS.M

1970/71),

provided a large amount

of background information for

the

Review. At the time of pre-

paration -0f the Review not all the sections of HUFSM (1970/71)

were available, although an ear l ie r less comprehensive, f i rs t

edit ion (Automotive Safety Foundation ASF 1963) would

h ~ v e

been.

3.

.

The only

r e f e r e n c e ~ which have

been published since

the

Review

are the

a ~ d i t i o n a l sections

of HUFSM (1970/71)

and

the

National

Road Safety

Symposium (1972).

Two unpublished Australian

documents, Cowl

(1965)

and Donaldson

(1974), are too comprehensive

to

be

excluded

from

a.ny

considerations

of

Australian

studies.

4. Publications readily

avail

ab.le

in

the RRB l ibrary,

whet.her or not cited in

the Review,

have also been included

in

the

survey.

Information

on availabil i ty

of accident

and road

inventory

data

'for Australia.was

sought

via

a

mailed

questionnaire. A.copy

of

the

questionnaire

is

included

as Appendix A. Details

of

which

i terns are recorded on

acci

dent

rep.ort

fo.rms used in

the various

States and Territories can be supplemented by extract ing

in.forma-

tion from the

submission,

by the o m m o n w e ~ l t h

Bureau

of Census and

Sta t i s t ics

to the

House

of

Representatives

Select

Committee

on

Road

Safety

(

1973).


7/29

2

\RR

epor t

Mo.

l1 l

,

I

,J

7

> :

SURVEY OF LITERATURE

GENERAL

6.

Accident

frequency, severi ty

a n ~ type

are

~ i

cted

greatly

by the i n t ~ r a c t i o n s

of

various

driver,

vehicle, t ra f f ic environ

mental and

road

factors. For example., the you.ng

inexperienced

.

driver together with

drivers

known to have consumed

alcohol

have

high

accident rates

(Raymond 1967; 1970; Kornaczewski e t

a l

1972). Also, although urban areas experiencehigher

accident

rates overal l , rur.al.


8/29

ARR

Repo r t

No.

44 1975

J

a c c e p t e d. a s a b a s i

s

t o b e m d f i e d , i f n e c e s s a ry , i n 1 i g h t o f

further publications. A summary

of

the findings

relevant

to

rural

hi g hways a re. as o 1 1ow s .

(a).

The most

important

aspect

of

road

safety

in

road

design

is the reduction

in

the number

of

possible

points of conflicts between

vehicles. n t e r s e c ~

ti ans, me

di

an openings

and

d_ri

veways

should

be

kept

to a minimum consistent with

aspects of

service.

(b) Curves and grades are associated with

higher

accident rates. However, the road should be

designed with a uniform standard

of

fac i l i ty with

no

abrupt chariqes

in

geometry .

.

(c)

Increasing

the

road width improves

the

c ~ i d e n t

rate.

W i d ~ n i n g

lanes over 3.4

m,

however,

will

not reduce f u r ~ h e r the accident rate.

(d) Climbing

lanes

do

not

c o n t r i b u t ~ to reduced' accident

rates ,

but

increase

road

capacity.

(e) Increasing

the width

of shoulders

will

decrease the

accident

rate

provided shoulders are res t r ic ted to

emergency

u se

only.

(f) Adequate crossfaJl and superelevation should be

provided relat ive

to

ra infa l l intensi ty to inhibit

vehicles

hydroplaning in

wet

weather.

(g ) Skidding accidents

are

reduced i f a

high co

eff ic ient of fr ict ion of the

pavement

surface is

maintairied at all times ..

(h) The safest road

in

terms of accidents per vehicle

mile is

a

four-lane divided

highway

with

full

access

control

whereas .the least safe

is

a

four-lane

road

without

median and ~ o

access

control.

( i ) Re c o n s t r

u.

c t i o n o f a r o a d by e a s i n g c u r ve s , w d e n i n g

bridges and increasing sight

distance

will reduce

the

accident

rate.

(j)

Curve delineation is

h

effect ive measure for

reducing accidents on curves, part icularly at

night.

10. Geometrics as

defined in

the National Review 'includes

sight

distances, horizontu.l

alignment, vertical alignment, cross

section, number of

lanes,

lane

width,

shoulder

width, passing

lanes,

climbing lanes

and safety

ramps.

In reference to

Delaney's

l i s t (para. 7), this would be a

combination

of (a) and

(b).

In

the following

the factors

alignment (including sight

distance),

crossfa l l pavement width (including lane

width

and number

of

lanes)

and

shoulders,

and

the

l i te ra ture

related

to

them as

cited

in

the Review

will

be discussed, in deta i l ;

in

conjunction

with

other

relevant publications, with emphasis

on rural

highways.


9/29

4

.i\RR

R ep o r t

No.

4l1,

197 i

/.

ALfGNMENT. (including sight distance)

? .;:

11. In

studying

the

relat ionship between alignment

(both ;

horizontal

and

vert ical)

and highway

safety, researchers

have

..

-followed two

approaches:

(a) the correlat ion o f . a l i ~ n m e n t with accident

e x p ~ r i e n c e generally using multiple regression

techniques,

and

(b)

review

of basic

assumptions u e ~

to

derive

alignment design standards.

The current Review

of

Geometric Road Uesign

is following

basically

approach (b)

whereas

the

results

of

(a) are

the

concern of

this

present i n v e s t i ~ a t i . o n .

12.

Horizontal alignment

is

created by combining

circular

curves,

tangents

and

t ransi t ion spira ls ,

the

choice of radius of

c u r v a t ur e b e i n g b a s e d o n a s s u

mp

t

i

o ns . c o n c e r n n g d r i ve r ; ve h c

1e .

and roadway character is t ics , including fri ction factors and sight

distance. Thus, .strongly related to the selection of curves.is

the rate

of

superelevation used {see

NAASRA 1973,

also

the

f o l 1

ow

i n g s e c ti an on C o s

s

a l l ) .

13. V ~ r t i c a l

_alignment is crea.ted

by combinations of vertical

curves { c r ~ ~ t s

and

sags)

and

tangent sections

of

a particular

g r a d i e n

t

As w th h o r i zon ta l a l i gnme n t , t he s e l e c t i o n o f r a t e s

of

grade

and

length .of

curve

deper.ds upon

assumptions concerning

driver, vehicle and roadway character is t ics , and

sight distance

requirements.

14. Three Australian studies , all based

on

information

from

New

South Wales - Cowl nnd

FnirliP. (1970), Gowl (1965)

and

Donaldson

(1974) - the las t two

being

unpublished

documents, have

c o m m e ~ t e d on the effect

of alignment

on accidents.

15.

Cowl and Fairlie (1970)

analysed

fatal accidents

on

rural

St.ate

highways

reported

by the

Department

of Main

Roads OMR).

N.S.W.

for three years

(1966

to 1968).

TABLE I refers

to

these

accidents analysed by

type of accident and

radius of curvature at

s i te

of

ac.:cident.

Excluding

those

not

s ta ted ,

50

per

cent

(360

out

of

724)

of

the fatal accidents

were

associated with curved

alignment. I f type of accident is .con.sidered,

then

62 per

cent

( 19 3

out of

312 ) of

s i n g l e veh i c l e o u

of

con t r o l a cc i dents

an

d

58 per .cent

(143

out of 245)

of head-on or sideswipe opposite

direction

coll isions

were associated with

curves. Although no

information.on the

distr ibut ion

of curves by radius of

c ~ r v a t u t e

.was

available for comparison, 70 per cent of all fatal accidents

a ~ s o c i a t e d w i t h curves

occurred

when

the

curve

radius

was

300

m

or

less.

As

Cowl and Fairlie {1970) indicated it

might

be expected

that accidents are more l ikely to be associated

with

iurves

of

.small

radius than

with

larqe radius curves

and

the results of

their

study

support

this

h y p o t h e ~ i s . If

curves of

450

m

or

less

are

con

sidered, then

82

per

cent (294 out of 3(50) of the fatal accidents

were

~ s s o c i a t e d with

such curves.


10/29

TA.BLE J

..

FATAL .ACCIDENTS DN RURAL 'sTATE HIGHWAYS

BY

RADIUS OF CURVATU-RE -AT ACCIDENT SITE AND TYPE OF ACCIDE:IT

. NEW S0

UT

H W

L

ES , 19 66-: T0 19 68*

Type

.of

accident

' -

Radius

-of

curvature

i n

metres

s t ra ight

300

I

3o5-45o > 450

Sub

Percentage Not Total

.

road

I

:

total

on

curves s ta ted

I

:

S . n g l ~

vehicle out of

control

119

l

139 24

30

I

62 62

16

I

32

8

i

I

r.an 0 f f

road 1

85

88

14

16

203

I

58

I

10 21

I

hi t object

over turned

on

road

Head-on or side

swipe

op po -

s i t e

di rec t ion

col l i s ion

Intersect1

on

acc1 dents

Acciqents involving t1Jrni111g

movements

Rear end col l i s ions

Pedestr ian involved

0th

er

Total

Number

Percentage

102

25

22

33

26

37

17

17

36

4

48.5

I

36 7

i

15

3

i

i

86

27

4

1

2

1

10 1

242 52

32.3

6.9

30

1

3

2

66

8._

8

8

6

1245

I

I

29

23

37

28

50

1724

\96.5

68

I

1

4 1

i

I

I

I

i

I

58

14

4

11

7

26

50

75

3

59

i

3

8 253

I

. i

i

29

23

37

1 29

1

5 1

26 750

3.5

100

*Includes

56

a c c i d e n t ~ which occurred -0n s t ra ight s near to a

curve.

where, fron the repor ted de ta i l s

.

the

curved al ignment.had

a

s igni f icant

effect-

cin

the accident occurrence.

Extracted from a b l ~ XIIC (Cowl and-Fai r l ie

1970)

where the equivalentcatego.r ies ar=,

in f ee t

100,0, 1010 - 1500> ~ n d > 1500. - .

7

4

>

;:o

;:o

;;c

:..

-;:;

:::.

' 1

M

z

i

c

.c-

3

......

1

..J

4

\.Jl


11/29

6 ARR

Repor t

No. 44, 1975

16. Donaldson

(1974)

has analysed

all

accidents

(casualty

and

property damage) t ~ p o r t e d

by

DMR, N.S.W.

having

o c c u r r ~ d on the

Sydney/Newcastle Tollway between 12 December, 1968 and 31 Decembsr,

1973.

Excluding

those

accidents

occurring

at

the

toll

barriers and

t raff ic l ights ,

72 per.cent

(355

out

of

495)

of the-'accidents

occurred

on curves. Seventy one per cent (353

out

of 495) were

classif ied as ' ran off road' accidents and 73

per

cent.(256 out of

353) of

these occurted on

curves. Of

all

accidents occurring on

curves, 38 per cent ( 135 out of 355) occurred

at the

370 m

radius

curves, that is , all curves less than 450 m. By c9.ns_idering

separately each

direction

of t ravel ,

a

total

of

66

curves

was

obtained. These were then considered by radius of curvature and

whether l e f t or

right

curve. (See TABLE I,I.) .. Only

15

per cent

( 10 out

of

66) of

the curves

had a

radius

of 370 m. Accident

' rates (A)

were calcula.ted

using

.no.

of accidents

on

curves

of radius

,

nq. of

curves

of

radius

x.

where xi co.rresponds to

the

ranges

of x

given

in TABLE II. For

curves of 370 man

accident

rate of 13.5 was calculated. This was

2.5

times the

average for

all curves.

Since

the study:by

Cowl and

Fair l ie

(1970)

considered fatal

accidents on

State

highways and

that

by Donaldson (1974) fata-1 accidents

on

a

To.11.way,

i t

could be

inferred t h ~ t the vehicles

involved

were dperating at 'reasonably

h i gh s p e e ds I Th u s i t c0 u l d b e c0 n c 1 u de

th

a t f 0 r - re a s 0 n a b l y

high speeds' ,

curves of radius

450 m

or less

have a

signif icantly

greater

accide.nt

rate

than curves

of

larger

radi i .

17. In

ccinsideririg

a minimum radius of 450 m i t

should

b ~

stated that

D o n a l d s ~ n

(1974) had recommended a minimum

radius of

900 m

From studies

summarised in HUFSM12 (19.71) a

radius of

600 m

appears a natur.al barr ier since

alignments

with radii greater than

this

produced

. a

rel.a t i vely

small

dec.rease

in accidents, while

alignments

w ~ i c h

are

sharper

produced a

rapid increae in

accidents.

However, before any definite conclusions can be drawn, more

detailed a n ~ l y s e s considering factors s u ~ h as free speeds and

t raff ic

volumes would

be desirable. Also, i l lus t ra ted b ~ l o w ,

consideration

should be given to

t ~ n g e n t

lengths

p ~ i p r

to s i te of

accident.

18. Kipp ( 1952) foun.d

that

short

tangent;

sections, i.nterrupted

by curves

.and intersections, had accident rates that were not

appreciably different to

those

for long

.tangent

sections. (S.ee

TABLE

III .

However,

for

curves

adjacent to tangents less than

4.8 km

in length, the accident rate was

1.3

accidents per

million

vehicle kilometres, while

the

rate for.curves

adjacent

to tarigents

more than 4 .8 km in

length

was

1.6

accidents per million vehicle

kilometrei,

.... Kipp (1952) h ~ s suggested that t h i s . d i f f ~ r e n c e

in

rates is

a reflection

of d r i v ~ r r e l a x ~ t i o n or

inat tent ion. While

not emphatically reflected in

the

rates

for

long tangents, i t

seems to be reflected in

the

ra te . for c ~ r v e s that t ~ r m i n a t e these

sections.

19. With- regard to vertical alignment, Donaldson (i974) found

no r e l a t i o n s h i ~ with accident f ~ e q u e n c y ; However,

of the

ten 370

m horizontal

curves

which

exhibited very

high

accident rates six

occurred iri conjunction with 6 per cent grades a v e ~ a g i n ~ ten ran


12/29

ARR .Re

p

o r N o . 4 4 , 1 9 7 5

7

TABLE I I ..

ACCIDENTS OCCURRING

ON CURVES - S Y D N E Y N E W C A ~ T L E

TOLLWAY

NEW SOUTH

WALES 12/12/68 TO 31/12/73

Curve radius.

x metres)

x ~ 450

4 5 0 < x ~ 610

6 l O < x ~ 760

7 6 0 < x ~ 920

920< x ~ 1 2 2 0 .

1 2 2 0 < x ~ 1 5 3 0

1 5 3 0 < x ~ 1830

x>1830

Tota

1

:L

=curve l e f t

R = curve right

Number of curves

L R T

5

7

3

3

7

1

3

2

32

5

7

5

3

7

4

3

34

10

14

8

6

14

1

7

5

66

T =

all

curves = L+R

Accidents

L R T

65 .

70

135

52 36

88

18

22

40

1 5 6

19 30 49

6 6

20

6 26

3 I 2 5

i84 171 355

Accident rate

L R .T

13.o

.14.o

13.5

7.4 5.1

6.3

6.0

4.1

5.0

0.3

1.7

1.0

2.7

4.3 3.5

6.0

6.0

6.7 1.5 3.7

1.5

0.7 1.0

5.8 5.0 ~ 4

Note that

all

curves in the range x ~ 4 5 0 m were all 370 m curves

TABLE III

ACCIDENT RATES

FOR TANGENT

SECTIONS

OF SPECIFIED

LENGTHS*

Section

Total

Percentage

i n

91;.h

ADT

Acc.

ratet

Ace/km

km

k m

0.8 114

0.8-1.5

92

1.6-3.6

106

3. 2.., 4. 7

71

>4.8 169

Total

552

of

km

20.7

16. 6

19. 2

12.8

30. 7

100

1996 .

2041

2085

2043

2237

.

;

0.81

o.87

0.99

0.

9.3

0.93

*Extracted

from tABLE I K i ~ p (1952), using

cbnversion

factor

, 1

mile.=

1.61 km

f

Accide.n.t

r a te= accidents per mi.llion vehicle, kilometres

Note: AD r

average daily

t ra f f ic

0.60

0 ~ 6 6

o.78

0 10

0.78


13/29

8

/\RR

Repo r t

No. f975

off road

accidents percurve)

and the

author

has suggested that

further ~ e s e a r c h

is

required

to

determine

whether

i t

is

the hori

z o n t a

1

a

H

g nme ri t a l on e o r t h e c o m i n a t i o n wh c h

re

s u s i ri

t

i e

high

accident

rate for

such curves.

20. Kihlberg and Tharp (1968) found tha t the

presen.ce

of

any

of

the

fo r ge ome t r i c f e at ures (grad i en t , cu vat ure , i

n

te

rs ec t i on s

an

d s t r u c t u

re

s ) , o r any comb i n a

t i

on o f

th

e m g e n e r a y ha d a de mo n -

s trable

effect in increasing accident ra tes with the larger the

number of f e a t u r ~ s simultaneously p ~ e s e n t

the

higher

the

accident

rat.es.

Attempts

a t ranking the four geometric features .as

to

-their

prominency in

increasing

accident rates did not

produce conclusive

resul ts but

indications were

that

gradient

had the least effec t o

accident rates . Care should be exercised in

i .nterpreting these

resul ts since the analysis deals primarily with

grades greater

or

l e ~ s

than 4 per cent and curvature associated with degree

o f ~ u r v e

greater

or

less

th.an

4,

approximately

430

m on

rural

h i g h w . a y _ ~ .

2:L

All the studies i n v ~ s t i g a t i n g vert ical alignment whirih:

w-er.e i-ncJuded. in the summary of HUFSM12 (1971) showed th.at

vert ical

al(gnme.nt affected accident rates . For ex ampJe, a study: of .exp.re.s.s-

w ay-s in Germany, by

Bitzel

(1956), found that

accidents

per miil,l; on

vehicle kilometres increased

from 0.5

for grades

l ~ s s than 2

per

cent to 2 . 1 for grades

of

6 to 8 per cent. Mullins and Keese (1961)

calculated

the following

accident

rates per

kilometre .based on nin:e

freeways :

Tangents

s t r a i gh t grades 3 .2

Cres t ve r t i ca l

curves

6.6

Sag v e r t i c a l curves 7.8

When accident

rates

were related to horizontal

curvature

and

alignment (see TABLE IV), the effec t of increase in

gradient

is

clear w_ith a

s igni f icant

change

occurring

? t 4 per

cent ,

which is

in

agreement

with the

value selected

by Kihlberg

and

Tharp (1968).

22.

. While

the

l i tera ture survey has indicated tha t (a) hori- ...

zontal

curves of

radius

less than

450 m

and (b) gradients

above 4 .

per cent

should be

avoided,

and

in part icular the combination of_

(a) and (b) , th.es.e would. be only

tentat ive

conclusions

since

further d e t a i l e ~ analyses

considering

factors

such

as

free

speeds,

t r ~ f f i c

volumes and

tangent

lengths are

desirable.

CROSSFALL

23. S i ~ c e

the

purpose of crossfall . is

to

drain

the

pavement

and to

provide superelevation

on horizontal

curves,

the recommended

rate

of crossfal l wi.11

vary with surface type

and

geog.raphic

location

of

the road. Basically

the

effec t of

crossfal l

on

accident rates is related to skidd1ng

resistance.

As HUFSM7

(19

70)

indicates ,

the possib i l i ty

of

hydroplaning must

be considered and

care

taken to

ensure provision

of

no

less

than

minimum

values of

crossfal l

through adeQuate c o n s t r ~ c t i o n c o n t ~ o l and miintenance.

NAASRA

(1973)

also

s tresses the

importance of

finishing pavements

to close

tolerances

as

a t

high

speeds

an

uneven

pavement can o f f ~

set much of

the

value of side f r ic t ion . Therefore, deformation of

the pavement during

the

l i fe - t ime must be a

serious consideration

when

specifying

the recommended ~ a t e of

crossfa l l .


14/29

ARR Repo r t No. 44, 1975

TABLE IV.

ACCIDENT

RATES RELATED

TO

HORIZONTAL

CURVATURE AND GRADIENT

GERMAN

EXPRESSWAYS*}.

Curve radius

(m)

A c de n ts p e r mi 1 1 i o n ve h k m o n g r a d i e n ts '

( i n p e r. c e n t )

0 -

l .

9

2

- . 3. 9

4

-

5

9

6

s

o

' '

.

>

4000 .

0.28

o 20

1. 0 5 .

L32

.. :

300

-

4000

0.42

0.25

1

30

1

55

200

300

0.40

0.20

1.50

L 70

' "

-

j

:

n,; o;: t

100

-

200

0.50

0.

71.

1..86

2.

0 1

. ;

:

:

.

.

::>:1

::>:1

::>:1

/

ct>

O

"

I

0

.

rt

I

.z

I

0

I

.i::--

.i::--

......

-..

v i


23/29

18

ARR

Repor t

No.

44

19:7 5

FINnTNGS ANn

R [ ~ O M M E N D T I O N S

43.

The

l i te ra ture survey

of both Australian

and

overseas

publications

has

not

p r o d u c ~ d

any

easily

explained

relat ionship

between accidents and

geometric design.

The following

conclusions

are suggested

for f u r t h ~ r consideration.

(a) Based on data from N.S.W. i t could be inferred that

horizontal curves of

radii. less

than

450 m

should

be avoided.. However, further investigation con-

s i d e r i ~ g t r ~ f f i c volumes free speeds and

l ~ n g t h s of

tangents

pMor

to curves are necessary.

b) For access controlled highways (expressways),

gradients

above 4 per cent are

associated

with.

signif icantly

greater

accident

rates.

However,

the

qualifications

given

.for (a)

above

also

apply

t6

(b).

c)

Results

~ f overseas studies suggest

that.

for two-

lane rural highways pavement widths of 6.8 m

corres-

ponding to 3.4 m lane widths may be

sufficient .

On

low volume rural highways na.rrower pavt;?ments, and .

shoulders, would be r ~ c o m m e n d e d i f based

on

economic

considerations which

include accident

costs.

.

(d) Complete details of road

inventory

d ~ t a

are

available

only for New South Wales, Australian Capital Terri tory

an

d No r

the

r n

I

e r r

i

to

r y .

Ma t

ch

i

n g

of

i

n

v

e n

to

r

y

re

co

rd

s .

w i ~ h

~ c c i d e n t

data would be a tedioui

m ~ ~ u l

task

except for South Australia

and Victoria w h i c h ~ h o w -

ever, do

not

have

complete road inventory

d a t ~ ~

Also, the

number

of locations

for which accidents

find

road inventory

details can be mat.ched accurately

is probably

too small.

to allow

definite

conclusions

being drawn from any

analysis.

.e) One data.source, MR fatal accident

reports ,

already has m ~ t c h e d acci.dent location and road

i n v ~ n t o r y

data

and ~ t is recommended that more

detailed analysJs using this

data

sourc:ebe

ini t iated.

. . .

(f) In

aqdition to

(e), the.

engineering investigations

of

fatal accidents already being

cond_ucted in other

States could be used to supplement the N ~ s . w . sample

s i ~ e

of fatal accidents, both in n u m b e ~ and i

covering a wider range of h i g h w ~ y design standards.

A

s t a n ~ a r d i s e d

report ,

incorporating

road inventory

deta i ls would need

to

be

developed

for this

task.

::


24/29

ARR Repor t No. 44, 197 5

19

APPENDLX, A

..;

;

I

>

RRB

QUESTIONNAIRE

ON

ACCIDENTS

ND

GEOMETRIC

DESIGN

. . . . .

Organisation .: . .

.

. . . . . . . . . . . . . . . . . . .

.

.

1.

Doesyour

organisation

maintain records which l i s t

Yes

No

i )

design

features

by

(a)

road

sect

i ans.*

.........

or

b)

.specific

locations

........

and

i i ) t raff ic

volumes

by a)

road

sections* . . . . . . . .

or

b )

specific

locations

........

*How is section d ~ f i n e d

in

your records?

,

. . . . .

.

. . . . . . . . . . . . . . . . . . . . . .

.........................

..........................

r ~

the

f o l l o ~ i n g available from t h ~ s e _records?

Available

(a)

section

length

(b)

average

daily

t raff ic

(c) ayarage

daily

t raff ic by

day ~ o f .wee_k

(d)

hourly tr.affi.t volumes

(e)

w ~ e t h ~ ~ a ~ c e s s limited

in

section

length

f)

g)

( h)

( i )

w ~ e l h e r

road

divided

width of

me di

an

number of lanes

Yes No

..........

.

.

. . .

. . . . .

presence of structures

.e:g. railway crossing,

bridge)

.

{ j

. ( k)

1)

m)

(

n)

(o)

(p)

i n t e r s e t i o ~ s

and _type

grade

curvature

crossfall/superelevation

width

of

(i)

p a v e m e ~ t

(i i )

sh o u

1

d.e r

sight

distance

clais

of roadway

ARS

:

1,2,3)

...........

..........

In Automated

Record

Form

Yes No

. . . . . . . . . .


25/29

2 ARR Repor t

No

44, 197:5.

2. Does

ybur

o r g a n i s ~ t i o n mainta in ,

possess , o ~

have. a ~ a i l -

able

{indicate

which}; da ta on

road accidents?

{a}

b)

{ c}

Yes . . . . . . . No

Are

the

fol lowing

avai l ab le

from the acc ident records?

type

of accident

{e .g.

ran

off roild, hcad-o 'n 'col l i s ion}

type of vehic le i n ~ o l v e d

sever i ty

of

c c i d e n ~

f

ata'1'

personal

in jury

proper ty damage

Available In

Automated

Re co rd Form . .

Yes No Yes No

... .. ..

...........

{d} each v e h i c l e s d i r e c t i ~ n bf

t ravel

pr ior

to

accident

.........

3. Does your record system pr'ovide. for

locat'ing

the s i t e

of

a

pa r t i cu la r a c c i d ~ ~ t within the roadway iwcti t in w h e r ~ the

acc ident

occurred

and thus

permtt .the data

covered.

iri

quest ion 1 to

Lie

matched w.ith the

.data

covered in ques. t ion

2? .

Manually

Auto.mated

Yes

Yes

. ..... .

No . . . . . . . . .

..........

No

4. Whom should we

contact i f

we

requi re

furth'er

informat ion?

Name

T i t l e - .

:

. .

L o c a t i o n ~ :

: .- . . . : . .

. .


26/29

ARR.Repor t No. 44 1975

5.

What studies or research projects re la t ing accident r.ate:s

to road . features

are

current ly being

Qr have been.

con-

d u c t e d . i n

y

o u r S t a t e a n

9

1 1 h o i s

i. r i

c

h

a r g o f t

h

e p r o j e c-t s

?

Name

Ti t 1e . . . . . . . .

Location

' '

'

6.

Are:there ~ y facets of the NAASRA

project

on which you

would l ike . to-pass .addi t ional comment?

Si

gne

d

Date

. .

.


27/29

22

ARR

R e p o r t No.

44,

1-975

REFERENCES

AUSTRALIAN

SUREAU OF SJATISTlCS

(1974} . . ~ o d i r ~ f f i c accidents

involving

casua l t i e s .

.Ref.

No. 30

Victorian

Office.

AUTOMOTIVE .SAFETY

FOUNDATION

(1963).

Traff ic control and

roadway

e.lements,

the i r

re la t ionsh ip to

highway

sa fe ty . Prepared by the

Automotive Safety Foundation

in

co-operation

with the U.S. Bureau

of

Public Roads.

BA L DWN , D M ( 19 4 6 ) . Th e

re

1 a t i on of h i g h way de s i g n an d t r a f

f

i c

acci dent

experience.

Paper presented

to

Committee

on .Planning

.and Traff ic Eng1neering.

AASHO

18 Dec.

BELMONT, ILM.

(1954)

Effect of shoulder

width

on

accidents

on

two-lane

tangents . HRB Bull.

no.

91,

pp . 29-32.

BILLION,

C.E.

and STOH NER, W.R. {1957) A

detai led

study

of

accidents as re la ted to

highway

shoulders in N ~ w York Sta te .

HRB Proc.

vol. 36,

pp. 497-508.

BITZEL, I .F . (1956) Effects of motorway design on accidents

in

Germany. Highws

Bridges

Engng Wks vol. 24, No. 1161, 17 Oct . ,

pp. 1, 3

and 4.

BLENSLY, R.C. and HEAD, J.A.

(1960 ), Sho.ulders

and

acident

experience on two.:..lane rural highways: a -summary.

HRB

Bull . No.

266, pp'. 28-33.

COBURN, T.M.

(1962).

The re la t ion between accidents and layout

On r ura

1

r o a d s . P r o c . 11 s t

AR

RB

Co

n f , v o

J .

1 ,

p

t 1 , p p . 5 0 2 - 7..

Also published

in

In t .

Rd Saf .

Tra f f .

Rev . vol. 10; no. 4, pp.

15-20. ' '

COMMONWEALTH BUREAU OF CENSUS AND STATISTits

(1971). (Now

Australian

Bureau

of

Sta t i s t i c s .

Submission to

theHouse

of

Representat ives Select C o m m i t t e ~ on Road Safety .

COWL, R.R.

(1965).

A study of the inf luence

of highway

geometric

de s i g n o n r o a d a c c i de n

ts

. M En

g

. t h e s i s , Un i v . o f N S W . S c h o o

of Traff .

Engng.

COWL.,

R.R. and

FAIRLIE.

M.B. (1970). An analysis of fa ta l and

to ta l accidants

on

r u ~ a l

Sta te highways in fiew

S o ~ t h Wales. P ~ o c

5th

ARRB Conf. ,

vol

5, pt

,3,

pp.

3.19-37.

CRIBBINS, P.D.,

HORN,

J.W., BEESON, F.V . and

TAYLOR,

R.D. (1967);

Median openings on

divided

highways: the i r

e f fec t

on accident

ra tes and

level

of se.rvice. HighUJ Res. Rec.

no.

188, pp. 140-57.

DART,

O.K: andMANN,L.Jr

(1970-).

Rural

hfghway geometry re la t ion-

ship to accident ra tes in Louisiana. HighUJ Res. Rea. no.

312, pp.

1-16.

DELANEY,

D.J. (1972). Building safe ty in to ro.ads. Paper p ~ e s e n t e d

a t

NationalRqad

Safety Symp., Canberra., pp. 410-5.

DONALDSON, W.R. (1974).

Accidents

on freeway No. 3 - Sydney/

Newcastle Tollway.

Berowra

to Calga . Presented to

NAASRA TEC

(20th

Meeting).


28/29

ARR

Repor t No.

44,

1975

23

HEAD

J.A.

and

KAESTNER

N.F.

(1956).

The relationshii:>-betwe_en

11ccide.rit

data

and the:,wi.dthof-gra.vel shoulders in r e g o n ~

HRB

Proc. ,

vol. 35, .pp.

558-76

.

.

HIGHWAY

USERS

.FEDERATION

FOR

SAFETY

AND

MOBILITY

{1970/71)

..

HUFSM

7

(1970) Chapter 7

- Cross sect ion and

pavement

surface .

HUFSM 11 (1971) Chapter

11

- General design.

HUFSM

12 (1971) Chapter

12

- Alinement.

JORGENSEN.

R.

{1966). Evaluation of c r i t e r i a

for safe ty improve-

ments on the

highways.

Report to

the

U.S. Dept of

Commerce, Bureau

of Public

Roads,

Office of Highway Safety.

KIHLBERG,

J.K.

and

THARP

K.J. (1968).

to

design elements _of rural

highways.

Accident

ra tes as

re la ted

HRB

NCHRP Rep.

47.

KIPP, O.L.

(1952)

..

Final

repor t

on

the

Minnesota

roadside

study.

HRB Bull.

no.

55,

pp. 33-7.

KORNACZEWSKI

A.,

WILKINSON, P. , RAYMOND

A., RANKIN

J.G.

and

SANTAMARIA

J.N. {1972}. Driving

convictions

of a

random

sample

of Victorian

drivers .

Aust. Rd

Res .

vol. 4,

no,

8

pp.

40-51:

MATSON T.M;;

SMITH, W.A. and HURD F.W.

(1955). Tra f f ia Engineer-

ing. 'Civil Engineering

Series . (McGraw-Hill:

New York.)

MULLIN

E.F. (1972). Road safe ty

and i t s i nfluence ~ n

road

design.

Paper presented a t

National Road

Safety Symp.,

Canberra, pp.

423-30.

MU

LLI

NS

, . B

. F.

K

. a.

n d KEESE , C . J . (

19

6 1) . F

re ew

ay t r a

f f

i c a cc i dent

analysis

a n ~ : s ; a . f e f . Y .

study.

HRB Bull. no. 291, pp.

26-78.

' '

i- . ..

NAASRA

{1973). Policy

f ~ r

geometric design

of

rural roads (metric

uni ts

) .

NATIONAL ROAD SAFETY

SYMPOSIUM

(1972). Papers re la t ing ta

the

ef fec ts of road

design

on road safety - Session 3C.

Dept of

Shipping

and Transport

(now

Department

of

Trarisport) .

OGLESBY C.H. and ALTENHOFEN M.J. (1969).

Economics of

design

standards for low volume rural roads. HRB

NCHRP

Rep. 63.

PERKINS, E.T.

(1957).

Relationship of accident ra te to h i g h w ~ y

shoulder

width.

HRB Bull. no.

151,

pp. 13-4 ..

R F F ~

M.S.

(1953).

In te rs ta te

H ~ g h w a y s accideni

stdy,

HRB Bull.

no. 74, pp.

18-45.

RAYMOND A.E.

(1967).

High r isk groups and

hazardous

pract ices .

Austra l ian Study

Week

on Road Safety Pract ices Paper .no.

17,

vol.

3.

(1970).

Drivers breathalysed

in

Melbourne

in

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Proc.

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th

ARR

B

Co

n f

.

vo

1.

5 , p t 3 , p p . 2 0 9 - 2 8 .

S.CHOPPERT

D.W. (1957) . . Predict ing t r a f f i c accidents fro'm

roadway

elements of

rural two-lane highways

with gravel .sht iulders .

HRB

Bull.

no. 158, pp. 4-26.


29/29

24

ARR Repor t

N ~

44, 1975

SINCLAIR and IGHGHT (197.3). Review of road

design

in

re la t ion to road safety. Dept of Transport .National Review NR/11.

STOHNER

W.R. (1956) . . Relationship

of

highway accidents to

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width

on

two-lane

..

r'ural

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New

York

State.

HRB Pr o

c..

, v o 3 5 ; p

. 5 0 0 4 . .

... . .

V E ~ S A C E

J . (1960).

Fac.toranalysis

of'roadwa.y and

accidentdafa .

HRB

Bull. no. 240, pp.

24-32.

' :.

,

.Report writ ten

by

.: .

~

; \

"

: ; : .,

1

1975 - accidentes and geometric designs - arr_44

Documents