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NBSIR 78-1554

NAT'L INST. OF STAND & TECH R.I.C.

AlllOM M3MDD7

An Analysis of the Behavior of

Stair Users

John A. Templer, Gary M. Mullet, John Archea

College of Architecture

Georgia Institute of Technology

and

Stephen T. Margulis

I

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

Washington, D.C. 20234

February 1976

Issued November 1978

Prepared for ©c

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Directorate for Engineering and Science

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NBSIR 78-1554

AN ANALYSIS OF THE BEHAVIOR OF

STAIR USERS

0.

John A. Templer, Gary M. Mullet, John Archea

College of Architecture

Georgia Institute of Technology

and

Stephen T. Margulis

Center for Building Technology

National Engineering Laboratory

National Bureau of Standards

Washington, D.C. 20234

February 1976

Issued November 1 978

Prepared for Directorate for Engineering and Science

Consumer Product Safety Commission

Washington, D.C. 20207

^ uXlaa^

~

I U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary

Dr. Sidney Harman, Under Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technoiogy

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
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Table of Contents

PREFACE vii

1. DESCRIPTION OF THE STUDY 1

1.1 SELECTION OF VIDEOTAPE SEGMENTS 1

1.1.1 Videotape Quality, Camera Angles

and Duration of Recordings 2 1.1.2 Types of Stair Users 2 1.1.3 Stair Types ..... 3

1.1.4 Recording Times 3

1.2 ANALYSIS 3

1.3 MATCHED SAMPLE 3

1.4 REPRESENTATIVE SAMPLE 4

1.5 CODING 4

1.6 OBSERVER TRAINING AND RELIABILITY 5

2. ANALYSIS AND RESULTS 6

2.1 THE RELATIONSHIP BETWEEN STAIR INCIDENTS AND

USER CHARACTERISTICS AND BEHAVIOR 6

2.1.1 Intrastair Behavior and Characteristics 6

2. 1.1.1 Results 6

2.1.2 Interstair Behavior and Characteristics 8

2. 1.2.1 Results 8

2. 1.2. 2 Testing for Independence 9

2. 1.2. 3 Dynamic Effects 10

2.2 AN EXAMINATION OF THE RELATIONSHIP BETWEEN

STAIR INCIDENTS AND ENVIRONMENTAL FACTORS 10

2.2.1 Interstair Patterns of Stair Incidents 11

2.2.2 Interstep Patterns of Stair Incidents 13

2.3 SUMMARY OF FINDINGS 15

3. PERFORMANCE STATEMENTS TO GUIDE ARCHITECTURAL DESIGN THAT

SHOULD REDUCE STAIR ACCIDENTS 16
3.1 ALTERNATIVE VERTICAL COMMUNICATION ROUTES 17

3.1.1 Stair Avoidance 17

3.1.2 Signs 18

3.2 STAIR ENTRY AND EXIT LOCATIONS 18

3.2.1 Traffic Conflicts 18

3.2.2 Orientation Factors 19

3.2.3 Protective Gates 19

3.2.4 Dangerous Locations 20

3.3 STAIR PLAN CONFIGURATION 20

3.3.1 Mass Movement 20

3.3.2 Traffic Conflicts 21

3.3.3 Route Conflicts 21

3.4 VISUAL SURROUNDINGS OF STAIRS 22

3.4.1 Orientation Factors 22

3.5 STAIR LAYOUT HAZARDS 23

3.5.1 Headroom Under Stairs 23

3.6 FLIGHT DIMENSIONS 23

3.6.1 Headroom Clearance 23

3.6.2 Very Short Flights 23

3.6.3 Landing Frequency 24

3.7 FLIGHT WIDTHS 25

3.7.1 Flight Widths For Optimal Flow 25

3.7.2 Flight Widths for Comfortable Movement 26

3.8 VISIBILITY AND ILLUMINATION 26

3.8.1 Glare 26

3.8.2 Transitional Lighting 27

3.8.3 Night Lights 27

3.8.4 Light Switches 38

3.8.5 Levels of Illumination 38

3.8.6 Discrimination of Stair Detail 38

3.8.7 Shadows 29

3.9 RISERS AND TREADS 29

3.9.1 Dimensional Regularity 29

3.9.2 Riser-Tread Dimensional Relationship 30

Iv
3.9.3 Riser Dimensions 30

3.9.4 Tread Minimum Size 31

3.9.5 Nosing Overhang 31

3.9.6 Nosing Outline 32

3.9.7 Nosing Shape 32

3.9.8 Wash 33

3.9.9 Erosion 33

3.9.10 Coverings 33

3.9.11 Surface Texture 34

3.10 HANDRAIL LOCATION 34

3.10.1 Provide a Handrail 34

3.10.2 A Handrail on One Side Only 35

3.10.3 Handrails on Both Sides of the Stair 35

3.10.4 Handrails on Wide Stairs 36

3.10.5 Channeling 37

3.11 HANDRAIL HEIGHTS 37

3.11.1 Handrails for Children 37

3.11.2 Heights for Children and Adults 37

3.12 STAIR HANDRAIL DESIGN 38

3.12.1 Materials 38

3.12.2 Shape 38

3.13 GUARDRAILS 39

3.13.1 Stair Well Protection 39

REFERENCES 40

APPENDIX 1. Layout, Average Dimensions (Inches) and Surface of

the Stair Sample 41

APPENDIX 2. Coding Variables 50

APPENDIX 3. Tabulations of Statistical Material 56
LIST OF TABLES

TABLE 1. Behavioral Changes Made Immediately Preceding

An Incident 11

TABLE 2. Significant Characteristics of High Risk and Low

Risk Stairs 12

TABLE 3, A Comparison of High and Low Risk Stairs:

Environmental Changes 13

TABLE 4, Incidents Versus Changes in Stair Characteristics .... 14

TABLE 5. Incidents and Assistance in Stair Use 56

TABLE 6. Incidents and Reactions to Other Stair Users 57

TABLE 7. Incidents and Type of Handrail Use 58

TABLE 8. Incidents and User Group Ecology 59

TABLE 9. Incidents and Objects Carried; How Carried 60

TABLE 10. Incidents and Gait 61

TABLE 11. Incidents and Speed of Movement 62

TABLE 12. Incidents and Length of Clothing Below the Waist .... 63

TABLE 13. Incidents and Age 64

TABLE 14. Significant Characteristics of High and Low Risk Stairs:

A Comparison 65

vi
PREFACE

The Architectural Research Program of the National Bureau of Standards

(NBS) has been conducting research under an agreement with the Consumer

Product Safety Commission (CPSC). The objective of this work was to

recommend ways to reduce the frequency and severity of the approximately

350,000 stair, ramp and landing accidents that are treated in hospital

emergency rooms each year.

In order to expand our knowledge of stair accidents, several approaches

have been explored by NBS to identify potentially hazardous behavior.

To this end a videotape data bank of some fifty hours of recordings of

people using stairs has been collected. This material has been processed in various ways to provide information on typical human responses

to stairs.

In the report that follows, an analysis of the behavior of users of the

stairs recorded on the videotape segments is described. Fifty-eight

variables were used as measures of the stair user's characteristics,

user behavior and environmental conditions. The relationship between

these variables and the occurrence of incidents and mishaps depicted in

the data has been tested and conclusions drawn. An incident in the

context of the study does not necessarily imply a fall. As can be seen from Appendix 2, Incidents are categorized not only in terms of severity

and outcome, but also by type of precipitating misstep.

The sample of stair users, stair types and environments recorded on the

tapes cannot be considered as representative of the general population

of stairs and stair users. A representative sample would mandate the

selection of a much wider range of stair conditions, and a user population that is less identifiable.

The number of incidents that occurred in the fifty hours of observations

is not insubstantial from the viewpoint of illustrating the hazards.

But for the meaningful analysis the number of incidents and the number

of incidents per flight is small. In fact, on some flights no Incidents

were detected.

The validity of the conclusions that we have recorded from the analysis,

and the recommendations that we have made, are therefore limited by the

restricted nature and size of the sample. Nevertheless, until such a time as a considerably more extensive program can be undertaken, the

results provide useful indications.

Chapter 1 of this report describes the study and the methods that we

used; Chapter 2 sets out the statistical procedures and our findings;

in Chapter 3 we have made use of the conclusions from the videotape

analysis, and previous studies, to discuss the role of architectural

design in stair accidents. We have proposed 44 performance statements

which, if applied to stair design, would, we believe, substantially

vii
reduce the Incidence and severity of stair accidents. These statements

are presented and discussed in Chapter 3,

We would like to acknowledge the assistance we have had from the following people in conducting this study:

Dr. Robert Wehrli and Dr. Edward Arens, at the National

Bureau of Standards, for their administrative support,

and Joan Templer, Michael Jones and Amy Reynolds who were responsible for the coding analysis and who helped with the

production of this report.

viii
1.

DESCRIPTION OF THE STUDY

The purpose of this study is to:

° Identify hazardous and potentially hazardous responses by people

to various types of stair

"Diagnose the probable causes of these responses

"Suggest design guidelines that might contribute to or improve

standards of stair safety.

The method selected for the study has five stages;

1. Selecting a sample of videotape material for processing

2. Developing an observation and coding plan

3. Recording of the appropriate data

4. Analyzing statistically the data

5. Drawing conclusions and making recommendations.

1.1 SELECTION OF VIDEOTAPE SEGMENTS

A videotape data bank generated by NBS consists of about fifty hours of

recordings of people using stairs. These stairs are located in widely

separated parts of the United States, and are used by a variety of people. Both interior and exterior stairs were filmed, and stairs of various layout configurations and surrounding environments.

To reduce the data to a size that could be processed within the con- straints of the study, a selection process was adopted. The selection

process took into account:

" The visual quality of each tape segment

" The camera angles

" The duration and extent of the recordings

" The types of stair users

" The types of stairs and their environs

" The times at which the recordings were made.

1
1,1,1 Videotape Quality, Camera Angles and Duration of Recordings

Some segments of tape were excluded because the visual quality of the scene was inadequate for analysis. These were usually a result of

technical problems with the equipment, or light levels that were too

low for good quality videotaping. Only those videotape segments in

which the whole subject is clearly visible for a period long enough to

permit reliable coding of all applicable variables were selected for the

analysis.

1,1,2 Types of Stair Users

The subject matter of the tapes consists of recordings of:

“ Pre-school children at two day-care centers

* Elderly people at lunch programs at senior citizens centers

and general community centers

® Adolescents and young adults at a university student center

® A largely undifferentiated group of people at two shopping

centers and a memorial library.

From previous studies^ it has been established that children under the

age of four and adolescents have disproportionately high per capita

accident rates on stairs, compared to the rates for other segments of

the population. Subsequent analysis based on the actual frequency of

stair use have shown that persons over the age of 65 also have a disproportionately high accident rate on stairs. In addition to a high

risk of accidents on stairs, the injuries resulting from stair accidents

tend to be more severe among the elderly than among other segments of

the population. For this reason, it was decided to place special

emphasis in the analysis on the responses of preschool, adolescent, and

elderly stair users.

The fourth category is a largely undifferentiated group consisting of a wide variety of stair users. However, this group may not be representative of the general population of stair users. For example, young middle class white women appear to be over-represented. Nevertheless, this

group is sufficiently diverse so that it can be treated as indicative

of everyday users of stairs.

1 U,S, Consumer Product Safety Commission, NEISS News, January 1974,

2
1.1,3 Stair Types

The videotapes include material on several types of stairs in various

settings as set out in Appendix 1. This enables us to compare responses

to these different stairs, so long as the recorded user groups are comparable

Several of the staircases have "composite" layouts. They are composed

from straight flights coupled to landings in various configurations.

This permits us to treat these sections of stairs as if they are independent flights with different settings. Segments were selected that would

provide us with a sample from each stair type and setting.

1.1.4 Recording Times

The videotape recordings were made at various times of the day, and on various days of the week. It was necessary to consider the possibility

that stair incidents occur more frequently at certain times of the day, or on certain days of the week. Therefore, videotape segments that are

representative of various recording times were selected for analysis.

1.2 ANALYSIS

Two separate analyses of selected videotapes were conducted. The first

compared the personal and behavioral characteristics of people who had

accidents, missteps, or other incidents on stairs with the characteristics of a matched sample of users of the same stair who did not have

an accident or misstep. From this analysis, the relationships between

incident rates and the characteristics of users were established. The

second analysis compared the incident rates for representative samples

of users of each of the stairs for which data had been collected. From

this analysis, the relationships between incident rates and the characteristics of the stairs were established.

1.3 MATCHED SAMPLE

The National Bureau of Standards had already identified from the tapes

most of the stair incidents—where users fell, slipped, tripped or experienced an event that might have resulted in a fall. These incidents

were edited into six half-hour tapes. While some of these incidents did

not meet the selection criteria, those which met the criteria were used

to provide data on inter- and intra-user responses.

The characteristics of the people that were involved in incidents on the

stairs (the incident sample) were compared to the characteristics of a matching group of stair users who did not have incidents (the matched

sample). The matched sample was selected as follows: (1) the original

videotapes from which each incident had been edited were identified, (2)

3
for each incident victim a matching stair user from the same videotape

segment was randomly selected from the group of users who had traveled

in the same direction on the same stair at least one minute before the

victim. Except for the fact that the matching subjects had to satisfy

all criteria for tape quality, no other selection criteria were used.

This procedure ensured that the matched sample duplicated closely the

circumstances of the incident sample in terms of the time of day, the

day of the week, the stairway used, ambient environmental conditions,

and the general presence of other users. It also assured that the

behavior of each incident victim and his or her matching subject would

be sufficiently Independent of each other. The resulting groups represent a plausible basis for establishing valid relationships between

special personal or behavioral characteristics of the users and the

occurrence of stair accidents, missteps, or other incidents.

1.4 REPRESENTATIVE SAMPLE

The relationships between the architectural characteristics of the various stairways and the occurrence of incidents was established through

scrutiny of a representative sample of users on each flight. From the

large quantity of videotape that met all of the initial selection

criteria, a second selection procedure was undertaken to identify

approximately twenty percent of the total sample which would be

representative of the range of conditions under which recordings had

been made. After excluding tapes on which the users were predominantly

young or old, segments of videotape that represented activity at various

times of the day and various days of the week were selected at random.

From this representative sample, the frequency of stair incidents for

each flight was established. These incident rates were treated as the

dependent [or criterion] variables against which the characteristics of

the stairs and other environmental factors were correlated. From these

correlations, the relationships between the characteristics of the different flights and the incident rates were established. A further

analysis of the location at which incidents occurred within each flight

provided a more detailed understanding of the relationships between

stairway design and accidents or missteps.

1.5 CODING

Fifty-eight independent [or predictor] variables (See Appendix 2) were

selected for the analysis, each chosen for their possible influence on stair accidents. Many of these have been shown in previous studies to

correlate significantly with accidents.

4
The variables fall into three categories:

A. Stair user characteristics - such as age, sex, race, body type,

handicaps, clothing, items carried, group ecology, etc.

B. Characteristics of user behavior - including incident behavior,

direction of movement, speed, route taken, attention, handrail

use, traffic density, gait, reaction to others, etc.

C. Environmental conditions - including riser height, tread depth,

nosing, wash, illumination, stair width, handrails, time of

day, day of week, orientation factors, etc.

The user characteristics in categories "A" and "B" served as independent

variables in the comparison of incident and non-incident users in the

analysis of the matched sample. The environmental characteristics identified in category "C" served as independent variables in the comparison

of Incident rates on different flights in the analysis of the representative sample.

1.6 OBSERVER TRAINING AND RELIABILITY

Observer training occupied about seven hours. Much of the training was directed at raising the observer's reliability to an acceptable level.

(The reliability was checked periodically during the data processing

phase). During the period, the observer was familiarized with the:

° Operation of the videotape equipment

° Variables to be identified

° Coding procedures

° Recording procedures

The degree of observer precision decreases as the amount of observer

required judgment increases. Much of the training period concentrated

on improving the precision of recording judgmental factors.

5
2. ANALYSIS AND RESULTS

The analyses of the data are presented in two parts:

(2.1) An examination of the relationships between

Incidents^ and stair user characteristics and

behavior,

(2.2) An examination of the relationships between

Incidents and environmental factors.

2,1

THE RELATIONSHIP BETWEEN STAIR INCIDENTS AND USER

CHARACTERISTICS AND BEHAVIOR

In this first part of the analysis, we focus on the characteristics of

stair users and their behavioral responses to stairs. The hypotheses

to be tested are that some people are more likely to experience Incidents on stairs than others. The tests are directed at trying to

Isolate the reasons. This Includes examining the Influence of stair user characteristics (from the Group A variables In Appendix 2) such as age,

sex, race, body type, and dress. We also scrutinized people's behavior

on stairs. Does speed, direction of travel, carrying objects, being

alone, where the user Is looking, handrail use, or any other of the

Group B factors (In Appendix 2) affect the Incident rate?

These relationships are examined In two ways -- Inter- and Intrastalr

responses.

2.1.1 Intrastalr Behavior and Characteristics

For each stair, we have tabulated and described statistically the characteristics and behaviors of those users Involved In Incidents, By

matching we have virtually eliminated the possible contamination effects

of the environmental characteristics of time of day, traffic density,

ambience differences, etc, , and we are left with users’ characteristics

and behavior only,

2. 1.1.1 Results

One hundred and five Incidents were recorded from the videotape materials, As there were 43 flights, the number of Incidents per flight tended

to be small. In fact on some flights no Incidents occurred. On only

^ Of the 105 Incidents that were studied, 52% Involved a minor gait or postural adjustment, 30% Involved an aborted fall, and 18% Involved

body contact with the floor (a fall).

6
two flights were there sufficient incidents for any sort of intrastair

examination to be meaningful—stairs #1 and #17,

The characteristics of stair users involved versus those not involved in

2 incidents were compared, using contingency table analysis to the characteristics of a matching sample of users not involved in incidents.

The following variables were found to differ at a significance level of

.10 or less:

Stair #1

Variable #13 Length of clothing below the waist: More incidents than expected for those whose clothing is

above knee level.

Variable #15 Type of footwear:

More incidents than expected for those with

shoes that were not of the "regular" variety.

Variable #16 Type of heel:

More incidents than expected for those with a flat sole flat sole with no heels.

Stair #17

Variable #5 Age:

More incidents than expected for those whose

ages did not lie between 15 and 44.

Variable #16 Type of heel:

More incidents

flat sole with

than expected f no heels.

r those with a

Variable #18 Galt:

More incidents than expected for those whose

gait was "slow and deliberate."

Variable #23 User group ecology:

More incidents than expected for those who are

accompanied by one or more companions.

For all contingency tables comparing k independent samples of frequency

data in discrete categories, the test was used. In the case of two

independent samples of two categories each (a 2 X 2 table), the Fisher

Exact Probability Test was used. One or the other of these statistical

procedures was used with all the tables that follow.

7
2.1.2 Interstair Behavior and Characteristics

To extend this analysis so that we can generalize for all the stairs in

the study is not possible—the user populations are so different. However, it is possible to group all those stairs (at the two shopping

centers, the library, and the student center; stairs 1-22 in Appendix 1)

whose users represented a (largely) undifferentiated population into one

pool. So for this examination, all 51 incidents that occurred on these

22 stairs were pooled.

Once again, the characteristics of the users that were involved in incidents were compared with a matching sample of users not involved in incidents. The number of cases, is, of course, much greater this time and

therefore the tests have more power and precision.

2. 1.2.1 Results

The following variables were found to differ at a significance level of

.10 or less:

Variable //5 Age:

More incidents than expected for those whose

ages did not lie between 15 and 44.

Variable //13 Length of clothing below the waist:

More incidents than expected for those whose

clothing is above knee length.

Variable #16 Type of heel:

More incidents than expected for those who have

flat soles with no heels.

Variable #18 Gait:

More incidents than expected for those whose

gait was "slow and deliberate,"

Variable #23 User group ecology:

More incidents than expected for those who are accompanied by one or more companions.

The pooled data are used in this analysis because the users of these

stairs represented a comparatively unbiased and representative sample of

stair users.

For interest and comparison, a further examination was carried out using

a pool of all the incident data from all the stairs including those from

the schools and the facilities for the aged, (See Appendix 3, tables 5 to 14). From this analysis the following variables were found to differ

at a significance level of .10 or less:

8
Variable #5 Age:

More incidents than expected for those whose

age did not lie between 10 to 44 and are not

older than 64.

Variable #13 Length of clothing below waist:

More incidents than expected for those whose

clothing was above knee length.

Variable #17 Speed of movement:

More incidents than expected for those in the

second slowest speed category.

Variable #18 Gait:

More incidents than expected for those whose

gait was "unstable and tottering" and those

whose gait was "slow and deliberate."

Variable #19 Carrying objects, how carried:

More incidents than expected for those carrying objects, regardless of how carried.

Variable #23 User group ecology:

More incidents than expected from those who are accompanied by one or more companions.

Variable #35 Type of handrail use:

More incidents than expected for those whose

use of the handrail for "pulling up" and for

"balance.

Variable #38 Reactions to other stair users:

More incidents than expected for those watching

others or another.

Variable #39 Assistance in stair use:

More incidents than expected from those helped

by one person.

2. 1.2. 2 Testing for independence

Several of the latter group of variables may be correlated. Consequently, we have tested them for independence within both the incident

group and the non-incident group in all possible pairs in order to help

understand the results obtained with these groups. The following pairs

were found to be dependent at a significance level of .10 or less:

9
Incident Group

Age and: Length of clothing below waist, Speed, Gait, Carrying objects. User group ecology. Type of handrail

use. Assistance.

Length of clothing below waist and: Carrying objects.

Speed and: Gait

Galt and: User group ecology. Type of handrail use. User group Ecology and: Reactions to other users. Assistance.

Non- Incident Group

Age and: Length of clothing below the waist, Galt, Carrying

objects. User group ecology. Handrail use. Assistance.

Length of clothing below waist and: Carrying objects

Speed and: Gait, Handrail use. Reactions to other users and: Gait, User group ecology. Handrail use.

Handrail use and: Assistance

2. 1.2. 3 Dynamic effects

Next, for the incident group, we examined dynamic effects—where the

variables are under the user's control. For example, age does not change

during a journey on stairs but the object of the user's attention

may change and is therefore a dynamic effect.

Forty-three of the 105 incidents showed a change in one or more of these

controllable behaviors as the individual went from the last safe step to

the incident step. Table 1 shows this relationship.

It is not possible to generate a similar table for the non-incident group

since we cannot define a non-incident step. We can conclude that almost

half of the incidents showed a change in controllable behavior at the

time of the accident. No causality can be implied, however, because we have no basis for comparison with the non-incident behavior.

2.2 AN EXAMINATION OF THE RELATIONSHIP BETWEEN STAIR

INCIDENTS AND ENVIRONMENTAL FACTORS

In this part of the analysis, we focus on the frequency of stair incidents (as the dependent variable) in relation to the variables that

describe the steps, the stairs and other environmental factors. Again, we examine these relationships in two ways—interstair and interstep.

10
TABLE 1. BEHAVIORAL CHANGES MADE IMMEDIATELY

PRECEDING AN INCIDENT

Variable No, of Changes

Stair channel 7

Attention: Facing 2

Direction 12

Elevation 21

Apparent object of attention 20

Handrail use 9

Type of handrail use 9

Reactions to other stair users 12

2,2.1 Interstair Patterns of Stair Incidents

Using all the videotape segments from the representative sample, we com- pared the frequency of incidents on each of the various stair sections

(excluding those stairs where the uses were predominantly children or elderly people) on the hypothesis that certain stairs are more dangerous

than others.

Fourteen stairs were subjected to this analysis and every individual on each was categorized as an "incident" or as a "non-incident," These

data were subjected to a 2 x 14 contingency table analysis to test the

null hypothesis that incident rates were homogeneous across the stairways sampled.

The null hypothesis could not be rejected. However, putting the incident

data on a per step basis or an exposure risk basis, and using the same type of analysis, it was found that stairs #1, #5, and #20 had more incidents than could be expected by chance alone. Stairs #11, #12, and #22

had fewer.

The characteristics of these high and low risk sets of stairs were then

compared statistically (see Appendix 3, Table 14). The characteristics

were pooled when necessary to get expected values of 2 or 3. On the

basis of these analyses, the differences reported in Table 2 were found

at a significance level of .05 or less.

11
TABLE 2. SIGNIFICANT CHARACTERISTICS OF HIGH RISK AND LOW RISK STAIRS

Variable Partitioning Comment

Number of

steps

2, 3, 9 versus 12,

18, 24

All high risk in former

low risk in latter

Width 49 or 59 in, versus 60,

61 or 66 in.

All low risk in former,

high risk in latter

Riser height Less than 6.25 in.

versus 6.25 in, or greater

High risk stairs had

more in former class

than expected by chance

Tread depth 12 in, or less versus greater than 12 in.

High risk stairs had

more in former class

than expected by chance

Nosing

projection

All high risk stairs

had no projection

Stair surface Polished terrazzo

with insert versus

other

High risk had more in

former class than

expected by chance

Ascent

lateral view

Open one side versus

open one side rich

view versus open two

sides rich view

High risk had more

in middle class than

expected by chance

Descent

lateral view

ditto ditto

Descent

frontal view

Open front versus

closed front

High risk had more in

former class than

expected by chance

Ascent overhead view

Open above rich view

versus closed view

ditto

Descent overhead view

Open above versus closed above

ditto

Descent

orientation

gradient

One or less changes

versus two or more

High risk had more in

latter class than

expected by chance

12 i
In Table 2, the high risk group of stairs in comparison to the low risk

stairs: ,

had fewer steps per flight (fewer than 10) were wider (60 in. or more)

had lower risers (less than 6.25 in.)

had narrower treads (12 in. or less)

had no nosings

were finished in polished terazzo

had a rich view on one side (where a rich view connotes a view

with many people or conditions to attract the stair user's

attention)

had a higher magnitude orientation gradient (a larger number of

changes in orientation factors such as illumination and lateral, overhead and frontal view)^.

The high risk of incidents on stairs with few steps is further borne out

when all the incidents are considered relative to step number. Fully

one-third of stair incidents occurred on either the first or last step; an additional 25 percent occurred on the second or the next to last

step; and another 12 percent on the third or the third from the last

step.

2.2.2 Interstep Patterns of Stair Incidents

We then examined the three high risk stairs and the three low risk stairs

on a step-by-step basis. We analyzed the number of environmental changes

that occurred between successive steps (changes in width, wash, handrail

extent, riser height and other environmental conditions). The results

are summarized in Table 3.

TABLE 3. A COMPARISON OF HIGH AND LOW RISK STAIRS:

ENVIRONMENTAL CHANGES

No. of Environmental

Changes

High Risk

Cumulative %

Low Risk

Cumulative %

0 0 7.8

1 9.1 17.6

2 27.3 41.2

3 81.8 60.8

4 90.9 84.3

5 90.9 88.2

6 90.9 98.0

7 100.0 98.0

3 See Variable 57, Appendix 2, for additional information about the

orientation gradient.

13
In Table 3, the first row suggests that for the high risk group of

stairs, no two adjoining steps are environmentally identical. However

7.8 percent of adjoining steps in the low risk group are environmentally

identical. The second row of Table 3 finds 9,1 percent of adjoining

steps in the high risk group have one environmental change, but 17.6

percent of adjoining steps in the low risk group have one or no environmental changes. In all, the high risk group of stairs has more environmental changes present for the user who passes from step to step

than the low risk group of stairs.

We next looked at all of the 105 incidents, irrespective of the stair

on which they occurred. We focused on the number of changes in stair

characteristics (riser height, tread depth, etc.) that occurred between

the last safe step and the step on which the incident happened. Table 4

takes into account the direction of travel and ignores incidents on the

first or last step that would force a comparison with a landing.

Clearly, from Tables 3 and 4 we can conclude that uniformity in stair

characteristics from step to step is desirable.

TABLE 4. INCIDENTS VERSUS CHANGES IN STAIR CHARACTERISTICS

Number of Changes Number of Incidents

0 0

1 7

2 15

3 29

4 7

5 4

6 6

7 6

8 0

9 0

10 1

Finally, it was found that the high risk group of stairs differed significantly (P < .10) from the low risk stairs in the magnitude of the orientation gradient (specifically. Variable 58 in Appendix 2), The high risk

14
group had very few steps on which only one orientation factor (illumination, views) changed, and many steps where a large number of orientation

factor changes occurred.

2.3 SUMMARY OF FINDINGS

1. There are several variables that differentiate the incident group

from the non-incident group of stair users. The most important of

these appear to be:

° Age

° Length of clothing below the waist

° Type of heel

° Gait

° User group ecology

2. There is an association between the stair user's behavioral changes

that occurred just before the incident and the number of incidents.

In other words, many of the people in the incident group exhibited

one or more changes of behavior just prior to the incident. They

changed from one channel to another; they changed their attention or the object of their attention; they changed their type of handrail

use, etc.

3. It was possible to partition the stairs into high risk, low risk and

average, on the basis of their environmental characteristics. The

high risk stairs tend to have:

° Fewer steps

° Wider flights

° Lower risers

° Treads that are less than 12 in.

° No nosing projections

° A polished terrazzo finish with inserts

° Lateral views that are rich on one side

° An open front view

° An overhead view that is rich

° A high descent orientation gradient

4. All of the findings point to the need for homogeneity of design of

the stair environment from step to step. Not only should each step

match its neighbors in terms of dimensions, shape, etc., but the

surrounding environment that can be perceived from each step should

also match its neighbors.

Safety is also related to unchanging behavior as the users walk from

step to step on a stair, but obviously it is not possible to mandate

safe responses to the environment.

15
3. PERFORMANCE STATEMENTS TO GUIDE ARCHITECTURAL DESIGN THAT

SHOULD REDUCE STAIR ACCIDENTS

The Inherent instability of walking makes us prone to pedestrian accidents. Few days go past when we don't put a foot wrong, literally. We

slip a little on a slick surface, trip on a cracked sidewalk and recover,

or are thrown temporarily off balance pulling open a heavy door. Few of

these events are memorable because they are so frequent and so minor,

without serious consequence.

A misstep on a stair is obviously potentially much more serious than a similar error on the level floor. It is not surprising that stairs are

the loci for so many severely damaging accidents. A stair forces the

pedestrian to traverse a rhythmic or arrhythmic sequence of barriers,

to which, judging from the evidence of physiological metabolic studies,^

we are ill suited. We are well suited to walking great distances on

the level or over gently undulating ground. But stairs demand from us an unusual gait, coupled with (or producing) a very high rate of energy

expenditure.

Stairs are particularly bad places to have accidents. Falls in descent

are the cause of most serious stair accidents. To fall down stairs is

not only to fall over a cliff, but to fall onto the rocks below, for

the nosings of the steps often present a succession of sharp edges.

Any time that we fall as pedestrians, it is because of some physiological, perceptual or behavioral failures (unless the environment has

simply collapsed from under us). Some groups of people are more prone

to these failures than others. The videotape analysis confirmed other

accident studies that the young are more likely to fall. The elderly

may not fall more frequently than others, but when they fall, the

consequences are far more serious. The question that we must consider

here is the relationship between our failures and the environment. There

are few failures for which the pedestrian's environment is completely

blameless. We may stumble over our own feet, or a game leg may give

away, but usually the environment has failed us or at least we have

failed to respond to an environmental failure.

Hazardous environments are inevitable and pandemic, and we are reasonably well equipped to cope. Part of our equipment is natural caution.

We approach a precipice with circumspection, and we descend broken ground

with constant vigilance. This is not the case on stairs—familiarity

lulls us into a false sense of security.

Environmental hazards are acceptable where they are natural and predictable. We would not expect a mountain trail to be flat, level, protected.

1 Fitch, J. M., Templer, J. A., and Corcoran, P., "The Dimension of

Stairs," Scientific American, Vol. 231, No. 4, October 1974, pp. 82-90
without incident. However, we expect walkways, indoors at least, to be

hazard-free.

On stairs, then, as with walking on extended level surfaces, if there are hidden environmental traps, our lack of prudence or skill or perception will eventually be tested. In the sections that follow, we direc*" our attention to the major environmental traps of stairs and how people

respond to them. We offer a number of performance statements which are

intended to expose and finesse these usually subtle defects.

The performance statements in this chapter are verifiable from at least

one of three general sources, designated G (General Source), T (Templer),

V (Videotape), respectively:

G, The stair accident articles by Gowings (1960), Miller and Esmay

(1958), and Velz and Hemphill (1953) listed in the references,

T. Studies described by Templer in his forthcoming book, listed

in the references,

V. The videotape analyses described earlier.

3.1 ALTERNATIVE VERTICAL COMMUNICATION ROUTES

3.1.1 Stair Avoidance

Performance Statement (G)

Do not include stairs in designs unless they are strictly necessary.

Plan to keep staircase use to a minimum.

Discussion

Careful design and maintenance can make stairs safer, but the inherent

hazards cannot be wholly removed. One way to reduce accidents is to

reduce stair usage. One way to reduce usage in new designs is to

avoid staircases unless they are strictly necessary. Frequently a step

or a flight of steps can be omitted from the design after alternate

solutions have been explored.

If a staircase is unavoidable in design for a new building, then the

plan should aim to keep staircase use to a minimum. People should not

be required, for example, to use stairs to reach frequently used facilities such as toilets.

17
3.1.2 Signs

Performance Statement (G)

In public places, alternatives to stairs should be available (elevators,

ramps, etc). Information to this effect should be provided at the stair.

Discussion

If the elderly and the handicapped, for example, are unaware that alternative ways to ascend are available, they may try to use stairs. This

may be hazardous for them.

To reduce stair usage, all people should be encouraged to use safe alternatives wherever possible.

3.2 STAIR ENTRY AND EXIT LOCATIONS

3.2.1 Traffic Conflicts

Performance Statement (V)

Avoid a layout that will produce conflicting patterns of pedestrian movement in the vicinity of the top and bottom of the stairs.

Discussion

Stairs that are poorly located may bring into conflict pedestrian traffic

entering or leaving a stair and traffic passing the stair. Taking the

appropriate avoiding action on or in the vicinity of the stair in

response to a traffic conflict is to run the risk of a fall on the stair.

Videotape Examples

® A short flight of stairs leads to a landing from which one stair continues down in the same direction as the short flight,

and another continues down from the landing at right angles to

the other two. A woman at the bottom of the short flight and

intending to proceed straight nearly fell when another woman suddenly turned in front of her in order to take the other

flight.

“ A man intending to descend a stair has to make way for a group

ascending. He trips on the stair edging at the top of the stair.

%

18
3.2.2 Orientation Factors

Performance Statement (V)

Avoid changes of direction, changes of view and large changes in illumination level in the immediate vicinity of the top and bottom of the

stair.

Discussion

In the videotape analysis, it was noted that the incidence of accidents

on the top three and bottom three steps of the flight is very high.

On these high risk steps, a large number of orientation factor changes

occur—route direction changes, changes in view, and very large changes

in illumination.

It follows therefore, that stairs should be located such that orientation factor changes are minimized at the top and bottom.

Videotape Examples

° A man looking around at a visually rich environment catches his

heel on the first step of a short flight in descent.

° A boy looking down at a flight of stairs that starts at right

angles to the landing he is approaching misses the last step.

° A little girl descending is looking back up at the surroundings

and anticipates an extra step onto the landing at the bottom

of the flight.

° A little girl starts to climb a stair leading into a school. She

is looking up into the doorway and her foot slips off the step.

3.2.3 Protective Gates

Performance Statement (G)

If a stair is located where very young children play, the stair should

be provided with gates or some protective barrier at the top and bottom.

Discussion

The accident rate for young children on stairs is high. Some falls occur because the child crawls on the top landing and then falls down

the stairs.

19
3.2.4 Dangerous Locations

Performance Statement (G)

Avoid a layout where someone entering or exiting from a stair may be

subjected to an immediate and unexpected hazard.

Discussion

From the accident literature we learn of doors that open directly onto

a flight of stairs, and stairs that terminate at a street where oncoming

traffic is screened from view. In the former case, victims fall down

the stairs; in the latter case, victims were struck by other pedestrians

or even vehicles.

These are extreme cases perhaps, but it is quite common to find stairs

that terminate at a corridor or a walkway. The hazards may be less severe in these circumstances, but the dangers are avoidable by improving

the layout.

3.3 STAIR PLAN CONFIGURATION

3.3.1 Mass Movements

Performance Statement (T)

Stairs that may have to carry large numbers of people in the event of

an emergency should be designed to facilitate flow and to avoid configurations where people become trapped and crushed at a corner or on a landing.

Discussion

During peak movement periods, a dogleg stair (see stair No. 23 in Appendix 1 for an example of this type of stair) may perform inefficiently

but adequately. The flow of the stream of pedestrians will be particularly confused and uncomfortable at the landings. In the event of

panic, all flow may cease as the traffic becomes jammed at the landings.

The results then may be as catastrophic as in the Iroquois Theater Fire.

Five hundred people died within eight minutes, most of them crushed to

death on the landings of the staircase leading from the balcony^.

2 Schultz, D. P., Panic Behavior: Discussion and Readings , Random House,

N.Y., 1964, p. 9.

20
3.3,2 Traffic Conflicts

Performance Statement (V)

Avoid stair plan configurations that tend to encourage users to violate

the "keep right" rule and to use routes that will bring those descending

into conflict with those ascending.

Discussion

It has been demonstrated that with certain stair layouts, pedestrians

are more likely to select routes that may bring them into conflict with

others. A dogleg stair with the flights winding up to the left is an

example. The inside and shortest route, by custom, is for those descending and keeping to their right. As ascent requires much more effort,

stair users have been observed to move over to their left as they

approach the landing in order to take a shortcut. This brings them into

conflict with those descending. With the dogleg winding up to the right, on the other hand, the shortest route is given to those ascending.

There is no evidence that conflicting paths do or do not induce accidents, It is not unusual for pedestrians to come face-to-face, and to

take appropriate avoiding action. Stairs are potentially hazardous

places to walk and appropriate actions are circumscribed. There are few

choices available and the terrain is not level. Therefore, stair layouts

should not encourage pedestrian route conflicts.

Videotape Example

° A little girl ascending on the left of a dogleg stair collides

with a boy rapidly descending and keeping to his right.

3.3.3 Route Conflicts

Performance Statement (T)

Avoid paths to different areas of the building that cross on a stair.

Discussion

This is a special case of traffic conflicts discussed in 3.3.2. This

time it is not the configuraton of the stair that produces the flow

conflict, but the location of the stair within the environment. Two

streams of traffic may be entering a single flight of stairs in a transportation terminal, for Instance, and departing in different directions.

3 Templer, J., Stairs and Ramps , Dowden, Hutchinson and Ross, Stroudsburg,

PA., forthcoming.

21
It has been demonstrated that the "keep right" custom on stairs will be

violated routinely if there is a shortcut advantage to doing so,^

3.4 VISUAL SURROUNDINGS OF STAIRS

3.4.1 Orientation Factors

Performance Statement (V)

At no point on a stair should the user have to experience simultaneously

several orientation factor changes—changes in illumination, view, route

directions, and floor surface or level.

Discussion

From the videotape analysis, it was concluded that the high risk groups

of stairs had few steps on which only one orientation factor change

occurred, and many steps where a large number of orientation factor

changes occurred. People were suddenly exposed to a different and rich

visual environment, to sudden changes in levels of illumination, and

to alternative routes that were offered at the top or bottom of the

stair. Commonly these orientation factor changes occurred close to the

top or bottom of a stair where the user must exercise caution while

converting to a complete change of gait.

It cannot be concluded that the distracting nature of the surroundings

will induce incidents. However, de-emphasizing the surrounding views,

or masking manifestly interesting or changing views, will simultaneously

reduce the orientation factor changes. At those places where a number

of factor changes are inevitable, such as at landings, this strategy

should reduce the accident rate.

Videotape Examples

® A girl descending a stair and simultaneously drinking from a cup

and looking around at the surroundings catches the back of her

heel on the step.

° A woman descending turns around to look at some historic murals

and loses her balance.

® A middle-aged woman ascending is looking at murals and loses

her balance and nearly falls.

4 Templer, ibid
3.5 STAIR LAYOUT HAZARDS

3.5.1

Headroom Under Stairs

Performance Statement (G)

Where a stair rises over a walkway or a useable space, ensure that there

is adequate headroom beneath.

Discussion

If there is sufficient headroom under a flight of stairs, most people may

be able to avoid bumping their heads by ducking down or moving to a less

constrained route. However, those that have severe visual impairments

may not be able to detect the hazard. For all people there is the

possibility that an accident may occur because their attention is

distracted from the danger.

3.6 FLIGHT DIMENSIONS

3.6.1

Headroom Clearance (G)

Performance Statement

Ensure that the ceiling and light fixtures and other fittings cannot be

bumped by stair users.

Discussion

The ceiling may provide an adequate headroom, but lights and ornamental

fittings, etc., that are added often project too low. The hazard is not

only the risk of bumping into the object, but also the dangers of a fall

caused by a misstep in trying to avoid knocking against the object.

Headroom clearance should permit a substantial percentage of the population to pass without contact.

3.6.2

Very Short Flights

Performance Statement (V)

Special care must be taken in the design of flights of five risers or fewer to draw attention to the steps and to avoid distracting views from

the steps.

23
Discussion

From the videotape analysis, it was clearly apparent that most of the

incidents occurred on the first three or last three steps of the

flights. This offers a probable explanation for the high accident

rate on flights with few steps.

Obviously, there has to be some additional explanation, and it appears

that orientation factors play an important role. From the videotape

analysis, it seems that where a large number of orientation factor

changes occur, the number of accidents increases.

By definition, the transition from stairs to landings is an orientation

factor. Other orientation factors are route direction changes, changes

in views and very large changes in illumination level. All of these

events are more likely to take place close to landings. This suggests

that it is necessary to reduce the orientation factor changes on short

flights to a minimum, and to focus attention on the stairs.

Videotape Example

® A man ascends a flight towards a landing. From the landing a short flight rises to the right and another to the left. The

view of the surroundings is full of interest. The man, looking

at the environment, anticipates (wrongly) an extra step at the

bottom of the short flight,

3,6,3 Landing Frequency

Performance Statement (T)

Provide landings at intervals such that the distance that an accident

victim may fall is minimized.

Discussion

Landings serve at least two functions: (1) they reduce the potential

vertical distance that a victim of a stair accident might fall, and

(2) they provide a place for the stair user to stop and rest from the

effort of ascending stairs.

Stair use (in ascent) demands a high rate of energy expenditure for the

stair user regardless of the length of the flight. For the elderly and

for those with ill health, these demands are particularly taxing. However, all of these people can slow their rates of energy expenditure

by stopping on the stair, or climbing very slowly.^ Stopping on the

5 Templer, ibid
stair rather than on a landing may tend to be inconvenient to other

stair users, but then the same may be the case for the user who stops at

a landing and there is no place to rest away from the stream of traffic.

We assume that a fall from a greater height is likely to be more damaging than a fall from a lesser height. Furthermore, a fall on a stair

is not like a fall on an even surface like a ramp: the stair victim

is likely to strike a series of tread nosing edges. Therefore, flight

lengths should be kept short in order to reduce the potential vertical

distance that a victim might fall. However, as discussed earlier, very

short flights also should be avoided since these are associated with

increased risk of incidents.

3,7 FLIGHT WIDTHS

3,7,1 Flight Widths for Optimal Flow

Performance Statement (T)

Congestion on stairs is potentially hazardous. Stairs to carry heavy

traffic should be wide enough for the traffic to move at a comfortable

speed.

Discussion

If a stair is too narrow for the peak pedestrian traffic flow, a point

of congestion will occur when the speed of movement will slow greatly

or even stop sporadically.

As with walking on the level, a very slow forward speed makes balancing

much more difficult, and this is exacerbated on stairs when the body

is being raised or lowered past a step. At the same time, the stair users will have to gather much of their perceptual information about

the stair’s prevailing conditions through vicarious rather than direct

viewing.

While there is no evidence that these conditions cause accidents, the

potential for a mishap is clearly present.

In the event of an emergency, which requires the space to be rapidly

evacuated, the capacity of the stair may be of critical importance.

25
3.7,2 Flight Widths for Comfortable Movement

Performance Statement (T)

If passing movements or side-by-side travel on the stair are anticipated, the stair should be wide enough to permit individuals to proceed

without assuming an awkward gait.

Discussion

There is no evidence to show that there is a relationship between accidents and taking evasive action to avoid others on stairs. On the other

hand, there is evidence that any action that engenders an awkward gait

on stairs is likely to cause missteps.^

For two-way stair traffic, a minimum width of 56 in. between walls ana

69 in. for comfort have been recommended. We have made this recommendation, even though wide stairs are associated with increased risk of

incidents (see Table 2), because we do not believe that width itself is

a cause of stair incidents.

3.8 VISIBILITY AND ILLUMINATION

3.8.1 Glare

Performance Statement (V)

Avoid sources of glare in the field of view when traversing stairs.

Discussion

High lighting contrasts in the field of view may be caused by illchosen artificial or natural lighting design. The fault may lie in the

presence of a window on a landing at the bottom of an enclosed stair, or the presence of a light fitting hanging from the ceiling halfway

down the stair. In both cases, the glare reduces the ability of the

stair user to see the stairs.

Videotape Example

° A woman descends a stair slowly and with care, holding onto the

handrail, and looking down the stair. There is glare from a bright

patch of sunlight from a window in front of her. She misjudges,

catches her heel on the stair and loses her balance.

^ Fitch, et al, , "Dimensions of Stairs,

^ Fitch, et al. , ibid.

26
3.8.2 Transitional Lighting

Performance Statement (V)

If a threshold, step or stair is located where there is a great difference in light levels, then special care must be taken to reduce lighting

contrasts

Discussion

Thresholds and steps are often located at the entrance to a building

where there is a large difference in the light levels between the inside

and the outside. The eye accommodates for low light levels much more slowly than for high levels, so entering is often more difficult. If

the sudden lighting change occurs on or close to a step, this creates

an additional orientation factor. The videotape analysis has shown that

there is a correlation between orientation factor changes and the incidence of mishaps.

To avoid this type of hazard, it is necessary to provide natural or artificial lighting in such a way that the abruptness of the lighting

level change can be softened.

Videotape Example

° A girl leaving a student center through a darkened lobby does

not notice a step's edge because of glare and because bright

sunlight has cast a shadow parallel to the step's edge.

3.8.3 Night Lights

Performance Statement (G)

If a stairway is located adjoining or within a pedestrian movement route

that may be used at night, and there is the possibility that people may

unintentionally enter into or fall down the stairway, then a night light

or some other protective or warning device should be provided.

Discussion

Accident studies provide many examples of people falling down stairs

that they did not expect to be there.® The presence of a stair on or close to a path or corridor that people use must be made obvious.

After dark, a permanent night light may be required.

8 Miller, J. A., and Esmay, M. L., "Stairway Falls," Home Safety Reviews,

Winter 1958, pp. 23-25.

27
3.8.4

Light Switches

Performance Statement (G)

Two-way switches controlling artificial illumination for stairs should

be located at the top and bottom of stairs.

Discussion

Accident studies have indicated that the use of stairs in the dark is

hazardous. If the light switch is at the top or the bottom only, then

3.8.5 stair use in the dark may be inevitable. This should be avoided.

Levels of Illumination

Performance Statement (G)

The level of illumination on stairs must be sufficient for the user to

be able to see without difficulty.

Discussion

Poor lighting conditions were indicated in one accident survey as con- tributing to accidents. However, few of the victims listed poor

illumination as a primary or secondary factor. Nevertheless, it is

self-evident that adequate illumination should always be present for

traversing such a potentially hazardous series of obstacles.

3.8.6

Discrimination of Stair Detail

Performance Statement (G)

Ensure that there is a clear visual distinction between the planes

representing the treads when viewed from above.

Discussion

It is self-evident that a stair should be clearly seen as a stair and

not mistaken for a ramp. Each step should be perceptible.

To achieve this, the eye must be able to discriminate between each individual step and its background. This discrimination will not be achievable if light levels are too low or if the ability to discriminate is

reduced by glare, or if the materials of the tread surfaces tend to

distract the eye.

Q Miller and Esmay, ibid.

28
There are many ways of emphasizing the discrete nature of each step

through the use of illumination and color.

3,8.7 Shadows

Performance Statement (V)

Prevent shadows from being cast on steps.

Discussion

From the videotape analysis, there are strong indications that more

incidents can be expected on steps that are partially in shadow from

artificial light sources.

There were too few steps shown on the videotapes with shadows from sun- light for reliable analysis, but there is no reason to suppose that the

results would be any different.

Videotape Example

° A little boy about to enter a building trips over the first step

leading up to it. The step is partially in shadow from bright

sunlight.

3.9 RISERS AND TREADS

3.9.1 Dimensional Regularity

Performance Statement (G)

Care must be taken to avoid the construction of stairs with risers and

treads that vary substantially in dimension from step to step.

Discussion

Tread depth and riser height dimensional irregularity was found in

several accident studies correlate highly with the incidence of

mishaps. The videotape analysis confirms these findings.

^ Miller and Esmay, ibid.

Velz , D. J., and Hemphill, F. M. , Investigation and Application of

Home Injury Survey Data in Development of Preventive Procedure , University of Michigan, School of Public Health, Ann Arbor, 1953.

29
3.9.2 Riser-Tread Dimensional Relationship

Peformance Statement (T)

Use a riser-tread dimensional relationship for human gait that is safe

and comfortable.

Discussion

Risers and treads, singly or in consort, on which it is difficult to

walk will engender missteps. For comfort and safety, certain combinations of riser and tread dimensions have been recommended.^^

7 in. risers with 11 in. treads

6 1/2 in. tt 11, 11 1/2, 12, or 12 1/2 in. treads

6 in. *• 11, 11 1/2, 12, 12 1/2, 13, 13 1/2, or 14 in.

treads

5 1/2 in. •• 11, 11 1/2, 12, 12 1/2, or 13 in. treads

5 in. II 11, 11 1/2, or 12 in. treads

4 1/2 in. " 11 in. treads

4 in. II " 11 in. treads

There is no experimental evidence for recommendations using treads larger

than 14 in. (which may be appropriate for external stairs). However,

to avoid unusual gait responses that are potentially hazardous, certain

precautions are necessary. Large treads that force the user into taking

unusually large or small irregular paces on the level should be avoided.

Treads that force the user to adopt a gait with one leg exclusively used

for making the vertical movement up the risers are uncomfortable and

probably more hazardous.

3.9.3 Riser Dimensions

Performance Statement (T)

For comfort and safety, risers should not be too large nor too small for

human gait.

Discussion

Studies of human gait on stairs have shown that risers that are smaller

than about 6.3 in. tend to engender more missteps in ascent. The

videotape studies offer some indicative confirmation of this. The high

risk group of stairs was found to have risers less than 6.25 in. while

the low risk group had risers greater than 6.25 in.

11 Templer

,

Stairs and Ramps.

30
In ascent, every riser is an obstacle so this suggests that the fewer

the risers, the fewer obstacles there are. Expressed differently, the

higher the risers, the safer the stair is. However, a point is reached

when the risers are so large that it becomes difficult to use them in

descent. The studies showed that this point is reached when the riser

is about 7.2 in. Risers larger than this were found to produce more missteps

3.9.4 Tread Minimum Size

Performance Statement (T)

Treads should never be so small that they force the stair user to twist

the shod foot laterally.

Discussion

If the treads of a stair are smaller than the shod feet of the users,

13 this elicits an awkward gait and a higher number of missteps. A small

tread cannot accommodate the whole foot. In ascent, this is of little

consequence because often only the front of the foot is set down on tread. In descent, however, the metatarsal heads of the foot must be

set down within the tread in order to maintain balance. If the tread

is less than about 11 in., then the action can only be achieved by assuming a crabwise gait.

The videotape analysis offers some indicative confirmation of this. It was found that the low risk group of stairs had treads wider than 12 in.

and the high risk stairs had treads narrower than 12 in.

3.9.5 Nosing Overhang

Performance Statement (G)

Where nosings are to be used, care should be taken to ensure that the

overhang is the same on each step of the flight.

Discussion

Accident studies^^ have shown that nosing overhang irregularities correlate significantly with the incidence of mishaps.

Templet, ibid.

Templet, ibid.

Gowings , D. D., "Accident Injuries Due to Falls," National Safety

Council Transactions, Vol. 6, 1960, pp. 59-62.

31
3.9.6 Nosing Outline

Performance Statement (G)

Avoid the use of nosing overhangs on which those with artificial limbs can catch the toes of their shoes in ascent.

Discussion

For many people with artificial legs, nosing projections are insurmountable in ascent, or very hazardous. The same problem is present with

certain types of open risers. "The American National Standard for Making Buildings Accessible to the Handicapped" specifically prohibits the use of these nosing overhangs.

3.9.7 Nosing Shape

Performance Statement (G)

The edge of the tread at the nosing should not terminate with a sharp

edge, nor should the nosing end with a large radius curve.

Discussion

Most stair accidents occur during descent. Generally, in descent the

first contact that the foot makes with the step is at the nosing. This

does not provide a large area of contact to prevent loss of friction if

the nosing has a sharp edge. Furthermore, the sharp edge is likely to

be eroded through use fairly quickly.

In ascent, a not uncommon accident is a trip which results in the shin

striking the nosing. With a sharp nosing this can be a more serious

mishap than with a rounded nosing. On the other hand, if the nosing is

constructed with a large radius curve, it reduces the size of the tread

and may make for an awkward gait as the foot tries to clear the nosing

in descent.

"American National Standard: Specifications for Making Buildings and

Facilities Accessible to, and Usable by. The Physically Handicapped,"

American National Standards Institute, Inc., New York, October 1961.

Gowings, "Accident Injuries."

17 Templer, Ramps and Stairs
3.9.8

Wash

Performance Statement (T)

To avoid water (and ice) forming puddles on treads and landings, they

should be given a very slight fall or "wash" toward the nosing.

Discussion

Liquid on the tread surface will reduce the coefficient of friction

between shoe and surface to a level that may be hazardous. To avoid

rain forming puddles on outdoor steps, some wash is essential. Wash may

only be necesary for indoor stairs that will be cleaned periodically

with water.

The wash should be very small and imperceptible and certainly not sufficient to significantly increase the risk of slipping on the tread.

3.9.9

Erosion

Performance Statement (G)

Avoid use of materials that will erode quickly as a result of heavy use.

Discussion

Uneven surfaces and irregular surface erosion has been found to be the

cause of some accidents.^® Wear is inevitable. If the traffic is so heavy that rapid erosion is unavoidable, then those portions of the

tread that sustain most of the damage should be designed such that they can be replaced easily when necessary.

3.9.10

Coverings

Performance Statement (G)

If the stair is to be fitted with a surface covering such as a carpet,

special care must be taken to ensure that the material is securely fixed

and will not stretch or bulge through use.

Discussion

Accident studies have shown that poorly fitted carpets can be blamed for some stair accidents. In some cases the poor fit was caused by bad

18 Gowings

,

"Accident Injuries.

19 Velz and Hemphill, "Home Injury Survey Survey Data.

33
installation, and in other cases by poor materials that have not retained

their shape.

3.9.11 Surface Texture

Performance Statement (G)

The surface of treads should be smooth, even and adequately abrasive to

provide a non-slip surface.

Discussion

20 Slips on stairs were found by observers to account for more than twice

as many falls as any other cause.

Slips in descent tend to be more severe than in ascent. In descent the

critical area is at the nosing, the place at which first contact is made

while the foot still has forward motion. If the tread is slick at this

point, then a slip is likely.

3.10 HANDRAIL LOCATION

3.10.1 Provide a Handrail

Performance Statement (G)

Provide a continuous handrail for the full length of every stair.

Discussion

2

The accident literature shows that serious accidents often occur where

(or because) there is no handrail available. For descent particularly,

because most accidents occur during descent, it is necessary for the

rail to be continuous to match the patterns of handrail use.

For the elderly and those with balance problems, or those with deliberate or handicapped gaits, the rail must be continuous and must extend

sufficiently to enable the first and last steps to be negotiated.

Miller and Esmay, "Stairway Falls.

Miller and Esmay, ibid.

34
I

videotape Example

A very old, blind woman with a walking stick is descending

some steps. She feels for a handrail. There is none within

reach. She loses her balance, but manages to recover.

3.10.2 A Handrail On One Side Only

Performance Statement (G)

On narrow stairs where a single rail is provided, a rail on the right

side for descent is preferable.

Discussion

From the accident literature we know that most serious accidents occur

22 in descent. We also know tht people tend to walk to the right of the

stair and therefore use the right handrail during descent. It follows

that this location is likely to be the most beneficial if only a single

rail is to be provided.

Videotape Example

° A young girl with an artificial leg has to use the only handrail

which is to her left.

° A boy descends on the right side of a stair. His foot slips off

the edge of the tread, but he is holding the rail and this prevents a more serious fall.

3.10.3 Handrails on Both Sides of the Stair

Performance Statement (G)

It is preferable to provide handrails on both sides of a flight of

stairs. This is particularly necessary for the elderly and the young.

Discussion

If no handrail is within reach, then from the accident literature*^ we know that the likelihood of a serious accident increases. A handrail

22

23

24

Gowlngs, "Accident Injuries."

Templer, Stairs and Ramps .

Miller and Esmay, "Stairway Falls."

35
on only one side of the stair may not be within reach. Furthermore,

not all people have equal strength or use from both hands and arms;

they may be restricted as to which rail they can use.

25 People tend to keep to the right on stairs , so for a handrail to be

conveniently at hand, for those in ascent and descent, a rail on both

sides is necessary.

For the young who have a disproportionately high accident rate, and for

the elderly who have the most serious accidents, it is particularly

necessary to ensure that handrails are available on both sides.

Videotape Example

° An old man descending a stair and keeping to his right is forced

to move aside for another old man ascending. There is only one rail and the man ascending is using it.

3.10.4 Handrails on Wide Stairs

Performance Statement (G)

If a stairway is sufficiently wide for two or more to walk abreast, then

handrails on both sides should be supplied.

Discussion

If the stairway is wide enough for two streams of traffic, then omitting

the rail on the one side would jeopardize a person in that stream in

the event of a misstep. It is clear from the accident literature that

the absence of a handrail within reach is linked to the incidence of

accidents severe enough to require hospitalization.

Videotape Example

° A girl descending on the left of a wide stair catches her foot

on the tread and reaches for the handrail. There is none on the

left side of the stair. She recovers her balance by leaning on

the wall.

25 Templer, Stairs and Ramps .

Miller and Esmay, "Stairway Falls.

36
3.10,5 Channeling

Performance Statement (T)

If the stair in a public place is to be divided into channels, then each

channel should be provided with handrails on both sides.

Discussion

The channeling of pedestrians on stairs can be an effective way of con- trolling flow in heavily used public areas. However, at peak periods

when congestion is present, the forward speed of traffic, even is it is

channelized, is greatly reduced. For many people, handrails are required

during ascent and descent to counteract the inherent instability of their

slow motion.

3.11 HANDRAIL HEIGHTS

3.11.1 Handrails for Children

Performance Statement (T)

For preschool age children, handrails should be lower than for the

general population.

Discussion

Very young children use a deliberate gait on stairs, first because their

walking skills are not fully developed, and second because for them the

risers are very high. So this group will tend to crawl up the stairs

and back down, or to hold the rail or someone's hand.

From the videotape analysis, and from the accident literature, we know

that the very young are more likely to have accidents than the rest

of the population; and we know that accidents are more likely to occur

(or are more serious) where there is no handrail. To provide for the

special needs of young children, it is desirable to locate handrails at

a height that is convenient for them.

3.11.2 Heights for Children and Adults

Performance Statement (T)

Handrails for adults and handrails for children should be installed at

a height that will be comfortably at hand during stair use.

37
Discussion

It Is self-evident that If handrail heights fall outside of a certain

range they will be Ineffective for guidance and support.

A handrail should be within reach. A handrail that Is low enough for

preschool children will be much too low for most adults, and a rail

that Is high enough to be comfortable for most adults may be useless

for young children. There Is no single height that Is convenient for

adults and young children.

There Is some consensus, not based on studies, that for adults the top of

the rail should be set 30 to 34 In. vertically above the nosing; and for

young children a second rail that Is 24 In. high should be provided.

3.12 STAIR HANDRAIL DESIGN

3.12.1 Materials

Performance Statement (T)

Handrails should be constructed of materials that are smooth. In places

that are not protected from the weather, the handrail should be a poor

conductor of heat.

Discussion

Handrails that are too hot or cold for haptic comfort and rails that

feel abrasive are likely to discourage use. This would be hazardous

for those with gait or balance limitation, and the very young and the

very elderly.

3.12.2 Shape

Performance Statement (T)

Handrails should be designed so that they can be grasped firmly with a comfortable grip, and so that the hand can be slid along the rail without encountering obstructions.

Discussion

In ascent, handrails are used with a series of grasping motions as some- thing to pull on. In descent the hand usually slides down the rail,

remaining In contact with It. In ascent and descent the rail Is used

as something to hold onto, lean on to, and to maintain balance with.

These actions can be carried out safely If the profile of the rail

38
comfortably matches the hands grip, and if the hand is not forced by

supports or other obstructions to loosen its hold on the rail.

Videotape Example

® The videotape segments provide confirmation of the way handrails

are used, both routinely and for emergencies.

3.13 GUARDRAILS

3.13.1 Stair Well Protection

Performance Statement (G)

To prevent people from falling off stairs or into stair wells, protection

must be provided.

Discussion

The accident literature is replete with examples of people falling into

unprotected stair wells, or falling off the sides of stairs, or even falling through balustrading that is spaced too widely. Other accidents

occur when the protective guardrail breaks under the load of the impact

of someone falling against it.

These accidents are preventable if adequate precautions are taken and

there are many appropriate countermeasures.

39
REFERENCES

1. "American National Standard: Specifications for Making Buildings

and Facilities Accessible to, and Usable by, the Physically Handicapped," American National Standards Institute, Inc., New York,

October 1961.

2. Fitch, J. M., Templer, J. A., and Corcoran, P. , "The Dimensions of

Stairs," Scientific American , Vol. 231, No. 4, October 1974,

pp. 82-90.

3. Gowings, D. D., "Accidental Injuries Due to Falls," National Safety

Council Transaction , Vol. 6, 1960, pp. 59-62.

4. Miller, J. A., and Esmay, M. L., "Stairway Falls," Home Safety .

5. Schultz, D. P. , Panic Behavior; Discussions and Readings , New York

Random House, 1964.

6. Templer, J. A., Stairs and Ramps , Stroudsburg, PA.; Dowden,

Hutchinson & Ross, Stroudsburg, forthcoming.

7. U.S. Consumer Product Safety Commission, NEISS News , January 1974.

8. Velz, C. J., and Hemphill, F. M. , Investigation and Application of

Home Injury Survey Data in Development of Preventive Procedures . University of Michigan, School of Public Health, Ann Arbor, 1953.
APPENDIX 1 LAYOUT, AVERAGE DIMENSIONS (INCHES) AND SURFACE OF THE

STAIR SAMPLE*

NO, PLAN RISER TREAD WIDTH SURFACE

11 60 Terrazzo

4

11 60 Terrazzo

TTn

k

3 6 11 59 Terrazzo

>

* THE INDEX TO APPENDIX 1 IS ON PAGE 49.

41
NO, PLAN RISER TREAD WIDTH SURFACE

> Ns

5.9 10.9 58 Terrazzo

5.9 n 60 Terrazzo

11 60 Terrazzo

>

/

5.9 11 59 Terrazzo

10 5.9 11 60 Terrazzo

42
NO. PLAN RISER TREAD WIDTH SURFACE

11 5.9 10.9 60 Terrazzo

12 5.9 11 60 Terrazzo

13 5.9 11 59 Terrazzo

14 5.9 11 59 Terrazzo

15 11 59 Terrazzo

>

43
NO.

17

PLAN RISER

6.5

TREAD

14.2

WIDTH

173

SURFACE

Travertine

18

20

21

22

6.5 14.2 89 Travertine

5.2 12 66 Granite

12 357 Granite

6.9 12.5 49 Concrete

44
NO. PLAN RISER TREAD WIDTH SURFACE

23 7.5 11.3 46 Steel

24 7.5 11.2 44 Steel

-r

25 8.2 13 43 Steel

if

26 7.6 13 44 Steel

<

J

27 11.8 81 Concrete

45
NO. PLAN RISER TREAD WIDTH SURFACE

28 5.5 12 90 Concrete

29 7.3 10.6 47 Concrete

'V30 10.6 43 Concrete

31 7.2 10.5 46 Concrete

/I i

32 7.2 10.5 46 Concrete

4

1

\

46
NO.

33

34

35

36

37

PLAN RISER

6.7

7.2

6.8

6.0

6.8

TREAD

9.7

10.9

12

14

12

WIDTH

83

88

71

55

55

SURFACE

Concrete

Terrazzo

Stone

Concrete

Steel

47
NO, PLAN RISER TREAD WIDTH SURFACE

39 5.3 36 168 Concrete

40 7.1 14 100 Grani te

41 5.6 12 59 Concrete

42 7 11 55 Terrazzo

43 6.9 10.9 55 Terrazzo

48
INDEX TO APPENDIX 1

Stair

Nijmber Stair Location Building '

1-15 Shopping Center A

16 **Excluded from analysis**

17-18 Presidential Memorial Library

19 **Excluded from analysis**

21-22 University Student Center

22 Shopping Center B

23-26 Pre-School/Day Care Center A School

27-32 Pre-School/Day Care Center B School

33-34 Senior Citizens Center A Community

Center

35-36 Senior Citizens Center B House

37 Senior Citizens Center C Church

38 **Excluded from analysis**

39-41 General Community Center A^

42-43 General Community Center B^

^ Stair use by elderly observed,

NOTE. The symbol > in the stair diagrams indicates the "up" direction.

49
APPENDIX 2

CODE VARIABLES

1. Stair Number 9. Vision

2. Time of Day 1. Not wearing glasses

2. Wearing glasses (including

3. Day of Week sun glasses)

3. Unclear

0. Unknown

1. Sunday 10. Use of Walking Aids

2. Monday

3. Tuesday 1. No special aids used

A. Wednesday 2. Cane(s) or walking stick(s

5. Thursday 3. Crutch(es)

6. Friday A. Artificial leg(s)

7. Saturday 5. Wheelchair

6. Walks with a limp

A. Subject ID Number 7. Other

GROUP A - STAIR USER 11. Upper Extermity Impairment

CHARACTERISTICS

1. No visible impairment

5. Age 2. Left arm impaired or

ml ssing

1. Less than 5 years 3. Right arm impaired or

2. 5 to 9 years old mi ssing

3. 10 to lA years old A. Both arms Impaired or

A. 15 to AA years old missing

5. A5 to 6A years old 5. Other Impairment

6. 65 years and over

6. Sex 12. Type of Clothing Below Waist

1. Male 1. Pants, long or short

2. Female 2. Skirt or dress

3. Doubtful, unclear 3. Other

7. Race 13. Length of Clothing Below Waist

1. White 1. Above knee

2. Bla ck 2. Below knee

3. All others 3. Floor length

8. Body Type lA. Fit of Clothing Below Waist

1. Very underweight 1. Close-fitting, tight

2. Average weight 2. Average

3. Very overweight 3. Very loose, voluminous

50
15, Type of Footwear

1. No shoes

2. Lace-up

3. Lace-up, untied

4. Strap or buckled

5. Slip-on

6. Other or unclear

7. Boots

16, Type of Heel

1, Flat sole, no heel

2, Regular heel

3, High heel

4, Platform shoes

5, Other, or unclear

6, No shoes

GROUP B - USER BEHAVIOR

CHARACTERISTICS

17, Speed of Movement

(Time taken to traverse 3 steps)

1, More than 4 seconds

2, 3 to 3,9 seconds

3, 2 to 2,9 seconds

4, 1,5 to 1,9 seconds

5, Less than 1,5 seconds

6, No observation possible

18, Gait

1, Unstable or tottering

2, Slow and deliberate

3, Unconcerned, normal

4, Jaunty, playful

5, Acrobatic, athletic

19, Carrying Objects - How Carried

1, Not carrying anything

2, Carried in hand

3, Carried on arms

4, Carried on shoulder

5, Other

20, Carrying Object - Side Carried

1, Not applicable

2, Carried on left side

3, Carried on right side

21, Carrying Object - Type of

Object

1, Not applicable

2, Human animate (child)

3, Non-human animate (pet)

4, Inanimate

22, Carrying Object - Size of

Object

1, Not applicable

2, Largest dimension smaller

than 12 in,

3, Largest dimension smaller

than 24 in,

4, Largest dimension greater

than 24 in,

23, User Group Ecology

1, Alone

2, Accompanied by one other

3, Accompanied by two or more

4, Other

24, Direction of Movement

1, Up

2 , Down

25, Incident Outcome

1, Non-incident

2, Sat down

3, Fell forward

4, Lost balance but did not

fall

5, Other

51
26 . Severity of Incident

1 . Non-incident

2. Minor gait or postural

ad justment

3. Aborted fall

4. Body/floor contact

27 „ Step Number

(The step on which an incident

occurred - or no Incident)

28. Incident

1. No incident

2. Foot slipped off edge of

tread (in ascent or descent)

3. Tripped over riser

4. Foot too far forward on tread

5. Caught heel on edge of

tread

29. Stair Channel

1. Left third of stair

2. Center third of stair

3. Right third of stair

(always in the direction

of travel)

30. User's Attention: Facing:

1 . Forward

2. Backward

31. User's Attention: Direction:

1. Left (in direction of

travel)

2. Center

3. Right (in direction of

travel)

32. User's Attention: Elevation

1. Up

2. Level

3. Down

33. Apparent Object of Attention

1. Steps

2. Other people on stair

3. Other people not on stair

4. Environment

5. Other, or unclear

6. Something carried

34. Handrail Use

1 . None

2. Left hand on left rail

3. Right hand on right rail

4. Both hands on left rail

5. Both hands on right rail

6. Left arm against left rail

7. Right arm against right

rail

8. Emergency reaction to

incident

35. Type of Handrail Use

1 . None

2. Physical support

3. Pulling up

4. Balance

5. Guidance

36. Density of Traffic Ahead —

Within six feet there are:

1. No people ahead of the

s ub je ct

2. 1 or 2 people ahead of

subject

3. 3 or 4 people ahead of

subject

4. 5 or 6 people ahead of

subject

5. More than 6 people ahead

subject

6. Unclear

52
37,

Density of Traffic Behind —

Within six feet there are:

Al. Illumination on Step

1 . No people behind the

subject

2. 1 or 2 people behind

subject

3. 3 or 4 people behind

subject

4. 5 or 6 people behind

subject

5. More than 6 people behind

subject

6. Unclear

38. Reactions to Other Stair Users

1. No apparent reaction

2. Watching another or others

3. Progress impeded by

another

4. Changing direction to

avoid others

5. Other

39. Assistance in Stair Use

1. Not helped

2. Physically helped by one person

3. Physically helped by more than one person

4. Not helped but holding

hands

GROUP C - ENVIRONMENTAL

CONDITIONS

40. Lighting Contrast

1. Step has no shadows on

it

2. Step in part shadow

from artificial light

3. Step in part shadow

from sunlight

4. Step in full shadow

5. Step in full light

1. Very high level of illumi

nation

2. Average level of lllumina

tion

3. Very low level of illumination

42. Obstruction on Stair

1, No obstruction

2, Litter on stair

3, Other (inaminate objects)

43, Steps in Flight

44, Stair Width

45. Riser Height

46. Tread Depth

47, Nosing Projection

48. Wash

(forward Inclination of a tread)

49, Handrail Extent

1. Handrail on user's left

only

2. Handrail on user's right

only

3. Handrail on both sides

4. No handrail present

(Always in ascent)

53
50. Stair Surface

1. Brushed concrete

2. Brushed concrete with

insert

3. Brushed concrete with

metal edging

4. Steel soil checker plate

5. Granite - rough f indish

6. Unpolished terazzo

7. Stone - rough finish

8. Polished terrazzo with

metal edge

9. Exposed aggregate

10. Travertine polished

11. Polished terrazzo with

insert

12. Vinyl asbestos

51. Ascent Lateral View

1. Open one side

2. Open one side with rich

view

3. Open both sides

4. Open both sides with

rich view

5. Closed both sides

Note: A rich view connotes

a view with many people or conditions to attract one's

attention.

52. Descent Lateral View

1. Open one side

2. One one side with rich

view

3. Open both sides

4. Open both sides with rich

view

5. Closed both sides

53. Ascent Frontal View

1. Open front

2. Open front plus rich view

3. Closed front

54. Descent Frontal View

1. Open front

2. Open front plus rich view

3. Closed front

55. Ascent Overhead View

1. Open above

2. Open above with rich view

3. Closed overhead

56. Descent Overhead View

1. Open above

2. Open above and rich view

3. Closed overhead

54
57, Ascent Orientation Gradient*

1. Constant, no change

2. Change of 1 factor

3. Change of 2 factors

4. Change of 3 factor

5. Change of 4 more factors

58. Descent Orientation gradient*

1. Constant, no change

2. Change of 1 factor

3. Change of 2 factors

4. Change of 3 factors

5. Change of 4 or more factors

* Note: Orientation gradient is

a measure of the cumulative

effect of the orientation

factors that are presented to

stair users as they pass from

step to step. The following

factors, in the form of a checklist, were used to code

variables 57 and 58: changes

in lateral, frontal or overhead

views; changes in illumination

on the step; changes in ambient

conditions; changes that will

induce a gait alteration such

as will occur at a landing;

and changes of direction of

pedestrian movement at the top or bottom of a flight.

55
APPENDIX 3

TABULATIONS OF STATISTICAL MATERIAL

TABLE 5 INCIDENTS AND ASSISTANCE IN STAIR USE

COUNT

ROW PCT

COL PCT

TOT PCT

NONINCIDENT

0

INCIDENT

1

ROW

TOTAL

LIGHT 1 NO SHADOWS ON ST 84 89 173

48.6 51.4 85.6

86.6 84.8

41.6 44.1

2

PART SHADOW - 1 8 9

ARTIFICIAL 11.1 88.9 4.5

1.0 7.6

.5 4.0

3

PART SHADOW - 8 3 11

SUNLIGHT 72.7 27.3 5.4

8.2 2.9

4.0 1.5

4

STEP IN FULL 4 5 9

SHADOW 44.4 55.6 4.5

4.1 4.8

2.0 2.5

COLUMN 97 105 202

TOTAL 48.0 52.0 100.0

RAW CHI SQUARE = 5.46952 WITH 2 DEGREES OF FREEDOM.

SIGNIFICANCE = .0649

56
TABLE 6 INCIDENTS AND REACTIONS TO OTHER STAIR USERS

COUNT

ROW PCT

COL PCT

TOT PCT

NONINCIDENT

0

INCIDENT

1

ROW

TOTAL

REACTIONS

1 NO APPARENT 91 88 179

REACTION 50.8 49.2 88.6

93.8 83.8

45.0 43.6

2

WATCHING OTHERS 6 13 19

31.6 68.4 9.4

6.2 12.4

3.0 6.4

3

PROGRESS IMPEDED 0 3 3

BY OTHERS 0 100.0 1.5

0 2.9

0 1.5

5

CHANGING DIREC- 0 1 1 TIONS TO AVOID 0 100.0 .5

OTHERS 0 1.0

0 .5

Column 97 105 202

TOTAL 48.8 52.0 100.0

RAW CHI SQUARE = 6.32231 WITH 3 DEGREES OF FREEDOM.

SIGNIFICANCE = .0969

57
TABLE 7 INCIDENTS AND TYPE OF HANDRAIL USE

COUNT

ROW PCT

COL PCT . TOT PCT

NONINCIDENT

0

INCIDENT

1

ROW

TOTAL

lANDRAIL USE

1 NONE 64 63 127

50.4 49.6 62.9

66.0 60.0

31.7 31.2

2

PHYSICAL 0 2 2

SUPPORT 0 100.0 1.0

0 1.9

0 1.0

3

PULLING UP 0 7 7 0 100.0 3.5

0 6.7

0 3.5

4

BALANCE 3 16 19

15.8 84.2 9.4

3.1 15.2

1.5 7.9

5

GUIDANCE 30 17 47

63.8 36.2 23.3

30.9 16.2

14.9 8.4

COLUMN 97 105 202

TOTAL 48.0 52.0 100.0

RAW CHI SQUARE = 21.21480 WITH 4 DEGREES OF FREEDOM.

SIGNIFICANCE = .0003

58
TABLE 8 INCIDENTS AND USER GROUP ECOLOGY

COUNT

ROW PCT

COL PCT

TOT PCT

NONINCIDENT

0

INCIDENT

1

ROW

TOTAL

ECOLOGY 1

ALONE 56 41 97

57.7 42.3 48.0

57.7 39.0

27.7 20.3

2

ONE COMPANION 18 24 42

42.9 57.1 20.8

18.6 22.9

8.9 11.9

3

2 OR MORE 22 40 62

COMPANIONS 35.5 64.5 30.7

22.7 38.1

10.9 19.8

4

OTHER 1 0 1 100.0 0 .5

1.0 0

.5 0

COLUMN 97 105 202

TOTAL 48.0 52.0 100.0

RAW CHI SQUARE = 9.09998 WITH 3 DEGREES OF FREEDOM.

SIGNIFICANCE = .0280

59
TABLE 9 INCIDENTS AND OBJECTS CARRIED; HOW CARRIED

COUNT

ROW PCT

COL PCT

TOT PCT

NONINCIDENT INCIDENTROW

TOTAL

OBJECTS CARRIED

1 NOTHING CARRIED 58 54 112

51.8 48.2 55.4

59.8 51.4

28.7 26.7

2

CARRIED IN HAND 30 39 69

43.5 56.5 34.2

30.9 37.1

14.9 19.3

3

CARRIED ON ARMS 2 9 11 18.2 81 .8 5.4

2.1 8.6

1.0 4.5

4

CARRIED ON SHOULDER1 7 3 10

70.0 30.0 5.0

7.2 2.9

3.5 1.5

COLUMN 97 105 202

TOTAL 48.0 52.0 100.0

RAW CHI SQUARE = 7.06557 WITH 3 DEGREES OF FREEDOM.

SIGNIFICANCE = .0698

60
TABLE 10 INCIDENTS AND GAIT

COUNT

ROW PCT

COL PCT

TOT PCT

NONINCIDENT

0

INCIDENT

1

ROW

TOTAL

GAIT 1

UNSTABLE 1 9 10

10.0 90.0 5.0

1.0 8.6

.5 4.5

2 SLOW AND 15 29 44

DELIBERATE 34.1 65.9 21.8

15.5 27.6

7.4 14.4

3

UNCONCERNED -NORM 61 39 100

61.0 39.0 49.5

62.9 37.1

30.2 19.3

4

JAUNTY-PLAYFUL 20 26 46

43.5 56.5 22.8

20.6 24.8

9.9 12.9

5

ACROBATIC-ATHLET 0 2 2

0 100.0 1.0

0 1.9

0 1.0

COLUMN 97 105 202

TOTAL 48.0 52.0 100.0

RAW CHI SQUARE = 18.18885 WITH 4 DEGREES OF FREEDOM.

SIGNIFICANCE = .0011

61

/
TABLE 11 INCIDENTS AND SPEED OF MOVEMENT

COUNT

ROW PCT

COL PCT

TOT PCT

NONINCIDENT

0

INCIDENT

1

ROW

TOTAL

SPEED 1

MORE THAN 4 0 3 3

SECONDS 0 100.0 1.5

0 2.9

0 1.5

2

3 TO 3.9 SECONDS 2 6 8

25.0 75.0 4.0

2.1 5.7

1.0 3.0

3

2 TO 2.9 SECONDS 30 16 46

65.2 34.8 22.8

30.9 15.2

14.9 7.9

4

1.5 TO 1.9 SECONDS 14 9 23

60.9 39.1 11.4

14.4 8.6

6.9 4.5

5

LESS THAN 1.5 10 8 18

SECONDS 55.6 44.4 8.9

10.3 7.6

5.0 4.0

6

NO OBSERVATION 41 63 104

POSSIBLE 39.4 60.6 51.5

42.3 60.0

20.3 31.2

COLUMN 97 105 202

TOTAL 48.0 52.0 100.0

RAW CHI SQUARE = 14.93048 WITH 5 DEGREES OF FREEDOM.

SIGNIFICANCE = .0107

62

(
TABLE 12 INCIDENTS AND LENGTH OF CLOTHING BELOW THE WAIST

COUNT

ROW PCT

COL PCT

TOT PCT

NONINCIDENT

0

INCIDENT

1

ROW

TOTAL

CLOTHING

1 ABOVE KNEE 19 38 57

33.3 66.7 28.2

19.6 36.2

9.4 18.8

2 BELOW KNEE 5 4 9

55.6 44.4 4.5

5.2 3.8

2.5 2.0

3

FLOOR LENGTH 73 63 136

53.7 46.3 67.3

75.3 60.0

36.1 31.2

COLUMN 97 105 202

TOTAL 48.0 52.0 100.0

RAW CHI SQUARE = 6.87369 WITH 2 DEGREES OF FREEDOM.

SIGNIFICANCE = .0322

63
TABLE 13 INCIDENTS AND AGE

RAW CHI SQUARE = 17.75401 WITH 5 DEGREES OF FREEDOM.

SIGNIFICANCE = .0033

64
TABLE 14 SIGNIFICANT CHARACTERISTICS OF HIGH AND LOW RISK

STAIRS - A COMPARISON*

TTreir

RISK

LOW

RISK

HIGH

RISK

[liw

RISK

No. of Steps

< 10 14 0 2.88 11.12

> 10 0 54

p<.01

11.12 42.88

Width

< 60 in. 14 0 2.88 11.12

> 60 in. 0 54

p<.01

11.12 42.88

Riser Height

< 6.25 in. 14 30 9.06 34.94

> 6.25 in

0 24

p<.01

4.94 19.06

Tread Depth

< 12 in. 11 24 7.10 32.90

> 12 in. 0 32

.01<p<.05

3.90 18.20

Nosi ng

Projection

0 in. 14 27 8.44 32.56

>0 in. 0 27

p<.01

5.56 21.44

* High risk stairs: 1,5, 20. Low risk stairs: 11, 12, 22.

Values for characteristics of high and low risk stairs in the two

columns at the left of the table are actual or observed values;

those in the two columns at the right are expected values under

the null hypothesis of homogeneity of values. The obtained level

of significance or p-level is in the middle column.

65
TABLE 14- CONTINUED

HIGH

RISK

LOW

RISK

HIGH

RISK

LOW

RISK

Stair Surface

Polished

Terrazzo w/ 12 30 8.65 33.35

Insert

Other 2 24

•01<p<.05

5.35 20.65

Ascent

Lateral View

Open 1 side 0 18 3.27 14.73

Open 1 side

w/rich view 9 21 .01<p<.05 5.45 24.55

Open 2 sides

w/rich view 3 15 3.27 14.73

Descent

Lateral View

Open 1 side 0 18 3.49 14.51

Open 1 side

w/rich view 9 21 .01<p<.05 5.82 24.18

Open 2 sides

w/rich view 4 15 3.69 15.31

Descent

Frontal View

Open Front 14 36 10.29 39.71

Closed

Front 0 18

.01<p<.05

3.71 14.29

All other variables showed no heterogeneity.
NBS-114A (REV. 1 1-77)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBSIR 78-15542. Gov’t Accession

No.

3. Recipient’s Accession No.

4. TITLE AND SUBTITLE

AN ANALYSIS OF THE BEHAVIOR OF STAIR USERS

5. Publication Date November 1978

6. Performing Organization Code

7. AUTHOR(S) John A. Templer, Gary M. Mullet, John Archea, and

Stephen T. Marculis

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No.

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Directorate for Engineering and Science

Consumer Product Safety Commission

Washington, D.C. 20207

13. Type of Report & Period Covered

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of most sigrtificant informatiort. If document includes a significant

bibliography or literature survey, mention it here.)

The National Bureau of Standards has conducted research for the Consumer Product

Safety Commission the objective of which is to recommend ways to reduce the

frequency and severity of stair and landing accidents. One of the several

approaches to identifying stair hazards is to videotape stair use in a variety of

public settings. About 50 hours of videotape of stair use have been collected and

it has been processed in various ways to provide information on typical human

responses to stairs and landings. This report of an analysis of videotape of

stair use focuses on the relationship between the occurrence of incidents,

including falls, and the stair users' characteristics, user behavior, and

environmental conditions. The analysis relies, in part, on a comparison of

matched samples of incident and non-incident user groups. Based on the findings

of the analysis, a literature review, and other research on stair use by the

authors, Ut performance statements are proposed which, if applied to stair

design, should substantially reduce the frequency and severity of stair accidents.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons) Architectural design; design considerations; dimensional

relationships; environmental design; safety; stairs; user needs.

18. AVAILABILITY [x] Unlimited

1 ! For Official Distribution. Do Not Release to NTIS

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

|21. NO. OF PAGES,

74

1 ! Order From Sup. of Doc., U.S. Government Printing Office 20. SECURITY CLA^ ^22. Price Washington. D.C. 20402. SD Stock No. SN00^^003 (THIS PAGET

$5.25 1 1 Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151 UNCLASSIFIED

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