TRANSPORTATION RESEARCH BOARD
82nd Annual Meeting
12-16 January 2003
Session 801
Roundabouts and Low-Vision Pedestrians
ROUNDABOUTS AND PEDESTRIANS WITH
VISUAL DISABILITIES:
How Can We Make Them Safer?
Lal C. Wadhwa
Head, Civil and Environmental Engineering
JAMES COOK UNIVERSITY
Townsville Queensland Australia
P03-6042
Thursday 16 January 2003
8:00 am - 9:45 am - Marriott
ROUNDABOUTS AND PEDESTRIANS WITH VISUAL
DISABILITIES:
How Can We Make Them Safer?
Lal C. Wadhwa
James Cook University
Abstract
Roundabouts are a common feature in Europe and Australia. They are becoming
increasingly popular in the United States. Their wide-spread use is credited to
increased safety, higher vehicle flow capacity and reduced delay to motorists at
roundabouts compared to traditional signalised intersections.
However, certain physical and operating characteristics of roundabouts such as
continuous flow, curvilinear layout, longer paths for pedestrians and no stopped phase
at roundabouts give rise to problems for pedestrians with vision impairment. Possible
solutions include improved design procedures relating to the location of cross walks,
use of traffic signals, provision of detectable warnings, etc. as well as the development
of mobility and orientation aids designed to help find and pursue a safe path through the
roundabouts.
Roundabouts
The era of modern roundabouts began in the United Kingdom in 1956 with the
construction of the first "yield-at-entry" roundabout. In 1966, a nationwide yield-atentry rule launched the modern roundabout revolution. Australia and most other
British-influenced countries soon built modern roundabouts. Countries such as the
United States, where people drive on the right side of the road, were slower to follow,
but many of these countries including France, Netherlands, Norway and Switzerland
have been rapidly catching up since the eighties. For example, roundabouts have
greatly increased in number in France since the adoption of the yield-at-entry rule on
national routes in 1983.
There are an estimated 40,000 modern roundabouts worldwide and over 250 in the
U.S. (with many more planned or proposed). The greatest roundabout ever built in
the US. is in Clearwater Beach, Florida. It carries up to 58,000 vehicles and 8,000
pedestrians per day. Each roundabout has been an outstanding success. Roundabouts
have been described as “the safest, most efficient and attractive form of traffic control
in the world”. (http://www.roundabouts.net/newpage3.htm) Roundabouts slow all
vehicles, provide refuges for pedestrians, and are the only traffic control device in
which trees can be planted, fountains can bubble or spray, statutes can sparkle into the
next century. When constructed as part of new road construction they are cheaper to
build than signalised intersections. If used instead of traffic signals they save money.
Their maintenance cost is almost zero. They require no electricity, no regular tuneups, no annual replacements of parts, suffer no blackouts and cannot be blown away.
Modern American roundabouts have produced remarkable safety records. Since this
experience is similar to the roundabout experience reported in other parts of the
world, the safety of roundabouts compared to other forms of control has been well
established. As a result, the number of roundabouts in the United States is expected to
increase geometrically in the next decade.
Physical characteristics of roundabouts







Roundabouts typically feature a circulatory roadway around a central island.
The centre island is raised and landscaped
Roundabouts have raised or painted splitter islands at each approach that separate
the entry and exit lanes of a street.
These splitter islands are designed to deflect traffic and thus reduce vehicle speed.
Splitter islands also provide a pedestrian refuge between the inbound and
outbound traffic lanes
A roundabouts is a substitute for signalisation, as well as a traffic calming device
Entering traffic yields to vehicles already in the circle.
Operational characteristics of roundabouts
A roundabout is a form of intersection design control that
 accommodates traffic flow in one direction around a central island
 operates with ‘give way’ or ‘yield’ control at the entry points, and
 gives priority to vehicles within the roundabout
Other operating characteristics include
i. continuously moving traffic in clockwise direction (anticlockwise in US, Canada,
and other right-side driving countries).
ii. vehicles yield at the edge of the circulating roadway until a gap in the circulating
traffic flow becomes available.
iii. design speeds at the entry throat range from 25-35 km/h while the circulating flow
speed are typically below 50 km/h
Capacity and safety of roundabouts
1. Increase in vehicle flow capacity
The primary objective of using roundabouts against other forms of intersection
control is increasing the capacity of an intersection. The reasons for increase in
capacity are the following:


Since traffic yields rather than stops, smaller gaps can be accepted.
Omission of lost time (yellow and red) results in higher capacity compared to
signalised intersections, especially at isolated locations.
The maximum daily service volume of a single-lane roundabout varies between
20,000 and 26,000 vehicles depending on the % of right turns and the distribution of
traffic between minor and major roads. A double-lane roundabout may service
40,000 to 50,000 vehicles per day.
2. Reduction in incidence of serious vehicle crashes
Roundabouts achieve crash reductions of 50 to 90 percent when compared to two and
four-way stop control and signalised intersections and greatly reduced severity on
those few crashes that do occur. Factors contributing to higher level of safety at
roundabouts include
 single lane roundabouts result in increased safety because crossing distances
are shortened
 lower overall speeds result in lesser severity
 pedestrian have to cross one direction of traffic at a time at each approach
 overall number of conflict points is reduced when compared to a traditional
intersection treatment. At a four-way intersection there are 32 possible conflict
points between vehicles and only eight at roundabouts. Pedestrians face six
conflicts when crossing only one leg of the road whereas at a roundabout they
only have two.
 more defined path for potentially conflicting vehicles
3. Reduction in delay and concomitant emissions
Signalised intersections with no retiming during off-peak period produce unnecessary
delays to stopped traffic when gaps on the other flow are available. Roundabouts
have lower delays than for equivalent volume signalised intersection. Factors which
contribute to increase in flow capacity also contribute to shorter delays.
Analysis of Safety at Roundabouts
a. Factors contributing to increased safety
Vehicle safety
Modern roundabouts deflect and slow entering traffic.
There are a reduced number of conflict points compared to uncontrolled intersection.
Lower operational speeds yield fewer and less severe accidents.
Slower speeds because of intersection geometry reduce accidents
Netherlands achieved 95% reduction in injuries to vehicle occupants with roundabouts.
Pedestrian safety
A splitter island provides a refuge for pedestrians that will increase safety.
Low speeds reduce frequency and severity of pedestrian-vehicle accidents.
b. Factors contributing to reduced safety for pedestrians and cyclists
Difficult for visually impared pedestrians to interpret vehicle-pedestrian priority.
No stopped phase for pedestrians who want security of a signal.
Tight dimensions of roundabouts may create an uncomfortable feeling to bicyclists.
Longer paths increase travel distances for both pedestrians and bicyclists.
Roundabouts may increase delay for pedestrians seeking acceptable gaps to cross.
Safety record for bicycles and motorcycles has been mixed. According to one study
in the United Kingdom, the percentage of accidents involving cyclists was higher in
roundabout accidents compared to other forms of intersection (Layfield and Maycock,
1986). Another survey in 1989 of mini-roundabouts in England, Scotland, and Wales
found that the crash-involvement rates of motorcycles and bicycles in 50-km/h speed
zones was about the same for four-leg mini-roundabouts as for four-leg signalised
intersections. However, the rate for cars at the mini-roundabouts was much lower than
at the intersections.
International Comparison
Causes of accidents at roundabouts
The relative frequency of the different causes of accidents at roundabouts is shown in
Table 1. In 1990, 202 accidents were investigated at 179 urban roundabouts in France.
In Australia, the analysis is based on 492 roundabout accidents in Queensland. The
U.K. data is from four-way roundabouts and single vehicle accidents not distinguished.
Type of accident
Single vehicle - entry
Single vehicle - circulating
Single vehicle - exit
Rear end - entry
Rear end - circulating
Rear end - exit
Multiple vehicles – entry, circulating
Multiple vehicles – circulating, exiting
Side-swap (multi-lanes) – entry, exit
Side-swap - weaving (circulatory)
Pedestrian on circulatory roadway
Others
Queensland
Australia
5.2
10.4
2.6
16.9
1.2
0.2
50.8
6.5
2.0
1.7
-2.4
France
10.0
16.3
2.5
7.4
0.5
1.0
36.6
5.9
5.9
2.5
5.9
U.K.*
8.2
7.0
71.1
3.5
10.2
Source: B. Guichet (1992), Arndt (1998), Maycock and Hall (1984).
The single largest cause of roundabout accidents is the failure to yield at entry to
circulating vehicles. The other major types are single vehicle crashes including
vehicle running-off the circulatory roadway.
As shown in Table 1, three major crash types have been observed at roundabouts
1. entering-circulating crashes as a result of drivers failing to give way at entry.
2. rear-end collisions
3. single vehicle crashes
Together these three types constitute 75-95% of all roundabout crashes and are shown
as the first seven categories of accidents at roundabouts.
Table 2: Proportion of major crash types at roundabouts
Country
Enteringcirculating
Australia
51
France
37
Germany
30
Switzerland 46
UK
20-71
Rearend
22
13
28
13
7-25
Single
vehicle
18
28
17
35
8-30
Subtotal
91
78
75
94
80
Crash
types
All
injury
all
all
injury
Type of
Roundabout
Single & multilane
Single & multilane
Single lane
Single & multilane
Single & multilane
Source: Brilon and Bondzio, 1998 in Roundabouts: An Informational Guide, FHWA, 2000
Crash rates
Crash rates are expressed as average annual number of injury crashes per roundabout
and per million entering vehicles.
Table 3: Average annual injury crashes per roundabout and per million entering vehicles
Country
Australia
France
UK
Crash frequency per
roundabout million entering
vehicles
0.6
0.15
0.045
3.31
0.275
US
1.5
0.08
Remarks
Many high volume, multi-lane
roundabouts
Maryland, Florida, single-lane
roundabouts
Source: Various
Reduction in crashes: Relative safety of roundabouts
Studies have conclusively shown that there is significant reduction in the frequency of
crashes on roundabouts compared to other types of intersections. In other words,
roundabouts are safer as shown in Table 4.
Table 4: Crash reduction: mean % reduction
Country
All crashes
Australia
41-61
France
Germany
36
Netherlands
47
UK
US**
37
** limited data
Source: Guichet (1997), Garder (1998)
Injury crashes
45-87
57-78
25-39
51
Since roundabouts may have been constructed to replace problem intersections with
bad accident history, the rate of reduction may be overstated.
It may be possible to improve the design of some roundabouts and further reduce the
crash frequency.
Pedestrian crashes at roundabouts
The risk of pedestrians being involved in a severe collision is low because of reduced
speeds at roundabouts. U.K. studies have shown a 50% reduction in crashes at
roundabouts compared to other forms of intersections (Maycock and Hall, 1984,
Crown, 1998).
Analysis of Crash Data at Roundabouts in Queensland Australia,
1997-2002
There may be variations in the accident reporting processes and/or definition of an
accident in different countries. In Queensland Australia, to qualify as valid, crashes
must meet the following criteria:
 the crash occurs on a public road, and
 a person is injured, or
 the value of the property damage is:
(a) $2500 to property other than vehicles (after 1 December 1999)
(b) $2500 damage to vehicle and property (after 1 Dec. 1991- 30 Nov. 1999)
or
 at least one vehicle was towed away.
Analysis of Queensland crash data for 1997-2002 has been analysed with particular
attention to pedestrians at roundabouts. However, information on visual disability is
not available. It was thought that contributing circumstances might provide some
insight into pedestrian disability but this has not been very revealing.
Table 5 shows the number of annual pedestrian crashes by severity levels at
roundabouts in Queensland for the period 1997-2002. The number of roundabouts in
the State road system is shown in Table 6. Number of crashes per roundabout is
shown in Table 7
Table 5: Number of Pedestrian Crashes at Roundabouts by Severity, Queensland,
1997-2002
Severity
Fatal
Hospitalisation
Medical treatment
Minor injury
Total
1997
1
0
7
2
10
1998
0
6
2
6
14
1999
0
5
6
3
14
2000
0
3
8
2
13
2001
1
8
10
2
21
2002
0
4
5
6
15
Table 6: Roundabouts in Queensland, Australia
Roundabouts
3-way
4-way
5- & 6- way
Total
1997
69
90
11
170
1998
72
115
14
201
1999
74
119
15
208
2000
87
123
12
222
2001
88
126
11
225
2002
92
131
10
233
Table 7 : Number of Crashes by Severity per Roundabout in Queensland
Severity
Fatal
Hospitalisation
Medical treatment
Minor injury
Total
1997
1998
1999
2000
2001
2002
0.006
0.000
0.000
0.000
0.004
0.000
0.000
0.030
0.024
0.014
0.036
0.017
0.041
0.010
0.029
0.036
0.044
0.021
0.012
0.030
0.014
0.009
0.009
0.026
0.059
0.070
0.067
0.059
0.093
0.064
Total number of crashes by severity level for the period 1997-2002 at roundabouts
and intersections are shown in Table 8. The data in this Table shows the relative
proportion of fatal and severe injury (hospitalisation) accidents based on the type of
intersection.
Table 8: Queensland Data Analysis (1997-2001)
Severity
No. of crashes
%
No. of crashes
%
No. of crashes
%
fatal
hospital medical minor
pdo
total
roundabouts
8
436
898
638
1509
0.2293 12.4964 25.7380 18.2860 43.2502
controlled
196
4670
8006
4733
12616
0.6486 15.4528 26.4915 15.6613 41.7458
uncontrolled
1226
13785
16613
9481
29017
1.7484 19.6586 23.6916 13.5207 41.3807
3489
100
30221
100
70122
100
The proportion of fatal crashes at roundabouts is only 0.23% compared to 0.65% at
controlled intersections and about 1.75% at uncontrolled intersection. Therefore,
compared to roundabouts, the probability of a crash resulting in a fatality is 3 times
greater at controlled intersection and about 8 times higher at uncontrolled intersection.
The effect of speed and the number of lanes (single-lane and multiple-lane
roundabouts) on the relative level of severity of accidents is shown in Table 9.
Special attention is paid to the accident severity and frequency in zones with speed
below and above 60 km/h.
Table 9: Effect of number of lanes, 2000 and 2001
Speed zone
km/h
fatal
Proportion of
hospital medical minor pdo total fatal accidents, %
single lane
63
68
27
94 255
1.1765
137
202
111 299 755
0.7947
200
270
138 393 1010
0.8911
0-50
51-60
0-60
3
6
9
61-80
81-100
>100
>60
12
29
1
42
58
226
5
289
38
176
1
215
77 206
322 845
6
14
405 1065
5.8252
3.432
7.1429
3.9437
0-50
51-60
0-60
18
84
102
479
2193
2672
multilane
647
379 1036 2559
3329 1914 4753 12273
3976 2293 5789 14832
0.7034
0.6844
0.6877
61-80
81-100
>100
> 60
63
790
897
509 1406 3665
170
1436
1218
614 2263 5701
19
103
82
49 187 440
252 2329 2197
1172 3856 9806
1.719
2.9819
4.3182
2.57
21
92
1
114
The above Table shows that



Less than 1% of all crashes at roundabouts in speeds upto 60 kmph are fatal
crashes.
This proportion increases to 4 times in higher speed zones.
The proportion of fatal crashes is slightly lower on multi-lane roundabouts.
Statement of the problem: Implications for vision impaired
Since crossing a roundabout requires a pedestrian to visually select a safe gap
between cars that may not stop, accessibility for people with vision impairment has
been problematic. Specific problems that exist for the visually impaired pedestrians
trying to cross roundabouts include
1. continuously moving traffic may reduce the pedestrian crossing opportunities
2. traffic may block the cross walk
3. visually impaired pedestrians relying upon their hearing to detect gaps in
traffic may have difficulty crossing roadway approaches
4. vision-impaired pedestrians listen for gaps in traffic to detect when it is safe to
cross an entry or exit lane. These pedestrians may be unable to detect gaps
with constantly moving traffic as traffic noise may never abate. Traffic in the
circulating lane of the roundabout may mask other noises.
5. there is no stopped phase for pedestrians who want the security of a signal.
6. longer paths increase travel distances for both pedestrians and cyclists.
7. pedestrians seeking acceptable gaps to cross face increased delays.
With traffic signals and stop sign intersections, break in traffic flow provide
identifiable and predictable periods (gaps) during which pedestrians can cross. Such
breaks usually do not occur at roundabouts. Research suggests that selection of
appropriate gaps at roundabouts is problematic for visually impaired at roundabouts.
Circulating vehicles can mask the sounds of entering or exiting traffic making it
difficult to identify an appropriate time to cross. At entry leg, it may not be clear
from auditory information whether a driver intends to yield to a waiting pedestrian.
Yielding behaviour may be difficult to detect. At exit legs, auditory information may
not be adequate to reliably convey whether circulating vehicles will exit or continue
around the circulatory roadway.
The curvilinear layout of roundabouts poses difficulty in obtaining information about
the location and direction of the crosswalk. Sidewalks (footpaths) often curve in large
arcs and seldom lead directly to crosswalks. Different sources of information are
required to locate crosswalk.
1. Key problems faced by visually impaired pedestrians wishing to
cross a roundabout.
The key street-crossing tasks for the visually impaired include:
a. detecting the intersection
b. locating the crosswalk and aligning the body in the direction of the
crosswalk
c. detecting an appropriate break in traffic flow
d. orienting or aligning body to the crossing direction
These are shown in Figure 1.
Key problem areas
detecting the intersection
(roundabout)
locating the crosswalk
and splitter island
detecting an appropriate
break in traffic flow – safe
crossing opportunity
Orienting or aligning the
body – crossing direction
In spite of the increasing popularity and safety benefits of roundabouts, visually
impaired pedestrians face serious access problems due to difficulties experienced in
determining appropriate times to begin crossing, locating cross walks, aligning to
cross the street and maintaining their heading while crossing. It has been suggested
that pedestrians are discouraged from manoeuvring roundabouts but the degree to
which pedestrian volume (specially vision impaired pedestrians) changes when an
intersection with signals or stop sign control are converted to roundabouts is
unknown.
The problems faced by visually impaired pedestrians are the result of inherent
characteristics of roundabouts, as shown in Figure 2.
2. Inherent roundabout characteristics causing problems.
Inherent characteristics of
roundabouts
Curvilinear layout – difficulty
in detecting location and
direction of crosswalk
At entry, yielding behaviour
difficult to detect from auditory
info. - difficulty in identifying
appropriate time to cross
Circulating traffic masks sounds
of entering/exiting vehicles difficulty in identifying
appropriate time to cross
At exit, difficult to detect
continuing or exiting – difficulty
in identifying appropriate time to
leave splitter island
Analysis of problem: Requirements for Safe Crossing by Visually
Impaired Pedestrians
The visually impaired pedestrian embarking on manoeuvring a roundabout needs
information about
a. the location of cross walk which may be provided by
 landscaping, pedestrian barriers and other architectural features
 standardised detectable strip across the sidewalk
 kerb ramps with returned edges aligned with crosswalk direction
 sufficiently steep kerb ramp slope to be detected underfoot
 aligning the slope of the ramp with the crosswalk
b. the location of splitter island
 signal the presence of a pedestrian refuge
 detectable warnings mark the beginning and end of a safe pedestrian area
 about 60 cm of detectable warning surface is required
c. crossing direction
 remaining in the crosswalk
 ultra-high contrast marking
 raising or otherwise marking the crosswalk edges to provide a boundary
 providing a raised guide strip at the centreline of the crosswalk
 constant-contact cane technique
d. safe crossing opportunities
 likelihood of drivers giving way to pedestrians
 crossing in front of stopped vehicle
 stop bars and LED in-roadway warning lights
 signals may be necessary to provide street crossing opportunities
 signals must optimise roundabout operations for both pedestrians and drivers
Possible design solutions
Approaches to making roundabouts safer for pedestrians with visual disabilities
should aim towards making them accessible. An accessible intersection is a street
crossing that is usable by pedestrians who have mobility, cognitive, and/or sensory
impairments. Intersection accessibility can be evaluated in a new or altered facility by
a comparison to accessibility standards for new construction and alterations
promulgated under several Federal statutes or adopted by a State or local government.
Design Issues
safety and accident prediction
capacity and delays
location
design considerations: design vehicle, design speed, sight distance, deflection, central
island, circulating roadway, entries and exits, splitter islands, signing, and landscaping
bicycle considerations
pedestrian considerations.
Consistency in Design Features
Similar design and operational features are highly desirable. These include
consistency in
location of crosswalks
design of splitter islands
use of bollards and pedestrian barriers
use of landscaping features
Some Possible Solutions
1. consider using an ‘all red’ pedestrian-actuated signal to stop traffic on
demand.
2. a pedestrian-activated signal equipped with locator tones can also assist people
with visual disabilities.
3. minimise crossing distances by making crosswalks as straight as possible
4. cues used for identifying that a street is just ahead and for determining when to
cross include
a. traffic sounds
b. orientation and slope of kerb ramps
c. textural differences between the street and sidewalk
d. detectable warning underfoot
e. locator tones at pedestrian pushbuttons
f. audible or vibrotactile information from accessible pedestrian signals
(APS)
5. other design elements to be considered for improving safety of low-vision
pedestrians may include
a. stop lines set back from cross walks
b. providing two wheelchair ramps per corner
c. defining sidewalk edges
d. uniform placement of pedestrian push buttons
e. reducing corner radii
f. extending medians into crosswalks
g. eliminating merge lanes and left turn lanes as far as possible
Roundabouts may be unsuitable where there are large numbers of pedestrians.
The major design recommendations derived from the studies are:
 Ensure motorists recognize the approach to the roundabout.
 Avoid entries and exits with two or more lanes except for capacity requirements.
 Separate the exit and entry by a splitter (ghost) island.
 Avoid perpendicular entries or very large radii.
 Avoid very tight exit radii.
 Avoid oval-shaped roundabouts.
Technologies
"Wayfinding" refers to the techniques used by people who are blind or visually
impaired as they move from place to place independently. The techniques are
commonly divided into skills concerning orientation and mobility. Technologies
designed to assist the visually impaired persons in orientation enhance the ability to
monitor one’s position in relationship to the environment. These technologies help
the visually impaired in identifying the directionality and distance of objects. The
mobility aids are designed to help find and pursue a safe path through the
environment. These technologies improve the ability to travel safely by detecting and
avoiding obstacles and other potential hazards. Long canes and guide dogs are
commonly used by people who are totally blind, and optical systems are generally
used by people with low vision.
Technologies
Mobility - aids designed to
help find and pursue a safe
path through the environment
Ultrasonic devices:
SonicGuide
Sonic Pathfinder
Mowat sensor
Nurion Polaron
Laser Cane
Orientation and navigation –
aids designed to identify
directionality and distance of
objects
Infrared technologies:
Talking signs
electronic and talking compasses
improved tactile maps
virtual reality maps
GPS
remote sighted guide concept
smart vision
Mobility Aids

The SonicGuide consists of a wide bandwidth FM sonar transmitter and two
receiver transducers mounted on eyeglasses. Audio feedback provided range
information coded as pitch and direction coded as an interaural amplitude difference.
The timbre of the signal indicated the texture or characteristics of the object being
detected. A refinement of this approach is the Kaspa system.
 The Sonic Pathfinder is a head-mounted, pulse-echo sonar system controlled by a
microcomputer that utilizes a musical scale tone progression as the user approaches an
object. The microcomputer supplies intelligence which presents only the most
important/closest target to the user at one time.
 The Mowat sensor is a hand-held ultrasonic obstacle detector that gives vibratory
codes according to range.
 The Nurion Polaron is another hand-held ultrasonic device based on the Polaroid
camera rangefinder sensor, and can be hand-carried or worn around the neck.
 The Laser Cane, with laser sensors built into the cane and auditory and vibratory
feedback, is also designed to indicate approaching obstacles. This device can also
detect dropoffs.
Orientation Aids
Talking Signs, developed at Smith-Kettlewell Eye Research Institute, are permanently
installed infrared transmitters communicating human voice messages to a hand-held
receiver carried by the user. The directionality of infrared beams helps the user locate
the source of the message from a distance. 1,000 Talking Signs have been installed in
San Francisco, including in a three-level transit station, bus stops, buses, public
buildings, private businesses, and traffic intersections. Other remote signage systems
have been proposed and developed using infrared or other technologies.
Some emerging orientation innovations include: electronic and talking compasses,
improved methods of producing tactile maps, development of virtual reality maps
allowing the capability to pan and zoom and overcoming some of the limitations of
tactile materials, and use of the Global Positioning System (GPS)
Future technological development may lead to the "remote sighted guide concept"
whereby a user could transmit a picture of the scene to a sighted person for
interpretation. Computer vision or "smart vision" techniques also hold out the
prospect of sophisticated software allowing analysis of pictures taken by a camera in
order to find the object or information the user is looking for.
Some organisations dealing with problems related to visually impaired
National Eye Institute of the National Institutes of Health
National Institute on Disability and Rehabilitation Research
NCHRP
ADA
The Access Board
American Council of the Blind
Interagency Committee on Disability Research (ICDR)
Accessible Design for the Blind, Inc
The Association for Education and Rehabilitation of the Blind and Visually
Impaired (AER)
The seeing Eye
References
(1) E.J. Myers. Press release on Lisbon, Md., roundabout; Hurst-Rosche Engineers,
Cockeysville, Md., April 13, 1995.
(2) P. Wessel. Information transmittal from Santa Barbara Public Works Department
to Peter I. Doctors, March 16, 1995.
(3) J. Goodway. Report by the Las Vegas Public Works Department, May 4, 1995.
(4) L. Ourston. "Nonconforming Traffic Circle Becomes Modern Roundabout,"
Unpublished report to Caltrans, October 1994.
(5) P. DeAragao. "Circles and Roundabouts: An Historic Review," Actes du
Seminaire "Giratoires 92," Nantes, France, Oct. 14-16, 1992. Research conducted by
the Institute of Transportation and Planning, Swiss Federal Institute of Technology,
Lausanne, Switzerland.
(6) P.H. Bovy. "Spectacular Growth of Roundabouts in Switzerland: From 19 to 720
Roundabouts in 15 Years," Actes du Seminaire "Giratoires 92," Nantes, France, Oct.
14-16, 1992. Research conducted by the Institute of Transportation and Planning,
Swiss Federal Institute of Technology, Lausanne, Switzerland.
(7) A. Dagersten. "Roundabouts in Switzerland and Sweden, Thesis 72," Department
of Traffic Planning and Engineering, Institute of Technology, University of Lund,
Lausanne, Switzerland, 1992.
(8) T. Giaever. "Application, Design, and Safety of Roundabouts in Norway," Actes
du Seminaire "Giratoires 92," Nantes, France, Oct. 14-16, 1992. Research conducted
by the Foundation for Scientific and Industrial Research at the Norwegian Institute of
Technology.
(9) F. Nunes da Silva. "The New Roundabouts in Portugal," Actes du Seminaires
"Giratoires 92," Nantes, France, Oct. 14-16, 1992. Research conducted by the
Graduate Technical Institute, Lisbon, Portugal.
(10) C. Shoon and J. Van Minnen. "The Safety of Roundabouts in the Netherlands,"
Traffic Engineering and Control, March 1994, pp. 142-148.
(11) Lauer. Center for Urban Transportation Studies, France.
(12) T. Brenac. "Roundabouts in France: Development, Level of Safety," Actes du
Seminaire "Giratoires 92," Nantes, France, Oct. 14-16, 1992. Research conducted at
the National Institute of Research on Transportation and Safety, Provence, France.
(13) W. Brilon and B. Stuwe. "Roundabouts in Germany: Recent Results Regarding
Capacity and Safety," Actes du Seminaire "Giratoires 92," Nantes, France, Oct. 1416, 1992.
(14) G. Maycock and R.D. Hall. Accidents at 4-Arm Roundabouts , Transport and
Road Research Laboratory, United Kingdom, 1984.
(15) P. DeAragao. "Mini-Roundabouts in Switzerland," Actes du Seminaire
"Giratoires 92," Nantes, France, Oct. 14-16, 1992. Research conducted at the Institute
of Transportation and Planning, Swiss Federal Institute of Technology, Lausanne,
Switzerland.
(16) B. Guichet. "Mini-Roundabouts in France," Actes du Seminaire "Giratoires 92,"
Nantes, France, Oct. 14-16, 1992. Research conducted by the Center for Technical
Studies of the Western Facilities, Nantes, France.
(17) R.E. Layfield and G. Maycock. "Pedal-Cyclists at Roundabouts," Traffic
Engineering and Control, June 1986, pp. 343-349.
(18) B. Guichet. "Classification of Accidents on Urban Roundabouts," Actes du
Seminaire "Giratoires 92," Nantes, France, Oct. 14-16, 1992. Research conducted by
the Center for Technical Studies of the Western Facilities, Nantes, France.
(19) J. Menard. "Lighting of Roundabouts," Actes du Seminaire "Giratoires 92,"
Nantes, France, Oct. 14-16, 1992. Research conducted by the Center for Technical
Studies of Facilities, Normandie, France
(20) http://www.access-board.gov/news/roundabouts-bulletin.htm
(21) Jacquemart, G., “Modern Roundabout Practice in the United States” Transportation
Research Board, Washington DC 1998; NCHRP Synthesis of Highway Practice No. 264
(22) Robinson, Bruce W.; Rodegerdts, Lee; Scarborough, Wade; Kittelson, Wayne;
Troutbeck, Rod; Brilon, Werner; Bondzio, Lothar; Courage, Ken; Kyte, Michael;
Mason, John; Flannery, Aimee; Myers, Edward; Bunker, Jonathan; Jacquemart,
Georges “Roundabouts: An Informational Guide” Turner-Fairbank Highway
Research Center, McLean VA 2000, FHWA-RD-00-067
(23) Bared, J.G.; Prosser, W.; Esse, C.T., “State-of-the-Art Design of Roundabouts”
Transportation Research Record, No. 1579, 1997, pp. 1-10
(24) Interagency Committee on Disability Research (ICDR), Interagency
Subcommitee on Technology, Wayfinding Technology Workshop, September 28,
1999, National Science Foundation Board Room, Arlington, Virginia
(25) http://www.apbp.org/rid2001.pdf