The easiest way to
measure the
ramp slope is by using a digital
level. Make sure the level is
calibrated properly and test the
slope at at least three places, near
the bottom, the middle and near
the top. Use the steepest slope
as the actual measurement since
the slope of the ramp can vary
along its length.
Use a smart level at 3 different locations
along the ramp to ensure consistency
and accuracy. Make sure the level is
calibrated properly before measuring.
Take three readings at each point and
average the results since readings can
differ slightly.
Use a laser sighting tube. The rise will
be the difference between dimensions A
and B.
Take site measurements. The rise will
be dimensions B plus A. It is often
possible to use joints and elements in
adjacent construction, like mortar joints
in a brick wall or the top of a foundation
as a datam to which measurements at
top and bottom can both be taken as in
the example above.
Design for construction
variation
Since ramp slope is difficult to
control in construction, especially
with concrete, designers should
specify slopes lower than 1:12 to
insure that construction variances
will not result in a non-complying
ramp.
Figure 1
Is the ramp slope 1:12 or less?
When a ramp has multiple segments, the steepest slope of all
segments is the governing slope or the ramp. There is a case where the ramp slope may
exceed this requirement. In existing buildings, where there is not enough space to add a
ramp with a slope of 1:12, slopes of from 1:10 - 1:12 are allowed for rises of up to 6 in.
and slopes of from 1:8- 1:10 are allowed for a rise of up to 3 in. In a ramp with
multiple slopes, a short steep run at the bottom of the ramp that meets theses criteria
can be used to gain some extra space. Handrails would not be needed on that segment.
Is the rise 30 inches or less for each run?
(see Figure 1)
Unlike slope, this rule applies to each segment (run) of the ramp.
A ramp can rise more than 30 in. overall as long as each segment does not exceed this
limit. It is also possible to have a segment that has a 40 ft. horizontal projection as
long as it doesn't exceed 30 in. of rise. In other words, there can be 40 feet between
landings if the slope of the ramp is 1:16 or less.
Section 4.8.6
Figure 2
Is the cross slope of the ramp surface no greater than 1:50?
The cross slope of a ramp or walking surface is important
because an excessive slope can make using a wheelchair or crutches difficult. There is a
tendency for wheelchairs to roll toward the lowest point thus making it necessary to
overcompensate on a incline that has a significant cross slope.
Section 4.8.6; 4.5
Example of slippery and
dangerous ramp surfaces
A typical pressure treated lumber
surface after just a few years' exposure
to sun, rain and foot traffic.
A simple non-slip surface is
broom finished concrete brushed
perpendicular to the direction of
incline.
Figure 3
Is the ramp surface non-slip?
Gratings along route of travel
Gratings
can catch the wheels of wheelchairs and the tips of
crutches. Long dimension of grating perpendicular
to route of travel.
Close up section through grating.
Figure 4
Is the smaller dimension of grating openings no more than 1/2 inch, and are long
dimensions of rectangular gaps placed perpendicular to the usual direction of travel?
Section 4.8.3
In measuring the width of a ramp with curbs, the
narrowest dimension, either between curbs or railings is the one that governs.
Various ramp configurations
Straight run ramp
Ramp with a level in the middle
Left or right turn ramp
U-Turn ramp
Figure 5
Is the clear width of the ramp 36 inches or more?
Section 4.8.4
Figure 6
Is there a level landing at the top and bottom of each run?
Curved ramps
The landing in this example would not
be within compliance because there is
not a 60" x 60" area where the ramp
changes direction. Note also that the handrail extensions should not protrude into the
60" x 60" area.
The landing in this example is within compliance because it
provides a full 60"
x 60" space.
Is each landing at least as wide as the ramp
and 60 inches long? (see Figure 6)
Figure 7
Where the ramp changes direction, is the landing at least 60 by 60 inches?
Section 4.8.5
A warped surface makes the wheelchair
roll towards the inside. Moreover, one
wheel of a wheelchair will not be providing enough traction to move it forward properly.
It is impossible to make a curved ramp
that does not have this problem although
it may not be apparent or present difficulty
if the ramp slope is shallow (shallower
than 1:12).
Figure 8
If the ramp rises more than 6 inches or is longer than 72 inches, does it have a handrail
on each side?
Handrails are required on all ramps except those that are very
short (less than 6 inch rise or 72 inch length). Such ramps are used as curb ramps and may
also be used in other places to overcome slight changes in level.
Examples from NYCHA buildings
Ramp with handrail on both sides and a continuous gripping
surface.
Figure 9
On dogleg or switchback ramps, is the inside handrail continuous?
A continuous railing at a landing is one that connects to the
railing for the next ramp section without interruption.
Ramp with a 2 inch curb and ballusters
spaced closely together to provide
protection from falling off. The width of this ramp should be measured at the curb
or
the hand rail, whichever is narrower.
Figure 10
Is the gripping surface continuous?
A continuous gripping surface is one that is not interrupted by
the bracket, a post or other object.
Figure 11
Are handrails fixed so that they do not rotate within their fittings?
Figure 12
Is the top of the handrail between 30 and 34 inches above the ramp surface?
There is not a 12" extension because
the 12" should be parallel with the
ground surface or ramp and not include
the curved return. Note that the dimension above is the actual field dimension, not the
correct design which is shown at the right.
There is a discrepancy in UFAS about how a handrail like the one above is to be
measured. In the UFAS illustration, the condition above is shown. However, the text
indicates that the 12 in. must be level. Usually, the last interpretation is used because
it is the intent of the text.
Figure 13
At ends of handrails, is there at least 12 inches of level handrail beyond the top and
bottom of the ramp segment?
Are the ends of handrails rounded or returned
smoothly to the floor, wall, or post? (see Figure 13)
Different examples of gripping
surfaces for handrails
Section 4.8.5; 4.26
Figure 14
Is the diameter of the handrail between 1-1/4 inches and 1-1/2 inches?
Does the shape provide an equivalent gripping
surface?(see Figure 14)
At wall mounted handrails, is there exactly
1-1/2 inches between the handrail and the wall?(see Figure 14)
Section 4.8.7
Design strategies for edge protection
Edge protection is needed so that
wheelchairs and crutches will not fall
off the ramp surface if a person
loses control.
Provide a 2 inch curb and handrail on
one side and a wall on the other.
Extend the width of the ramp surface
beyond the handrail.
A ramp with a 2 inch minimum
curb.
A ramp with walls on either side. The
clearance between the handrails must
be at least 36" wide.
Figure 15
If a ramp or landing has a drop off, does it have a 2 inch curb, a wall, railings or
projecting surfaces which prevent people from falling off?
Note: Although UFAS requries only a 2 in.
high curb, other accessibility standards require at least 4 in. It is good practice to use
a 4-6 in. curb because 2 in. is below the height of some wheelchair footrests. It is
better for the footrest to stop the chair than the small front wheel. The curb does not
have to continue under the handrail extension since the ramp ends before the extension
begins.
Section 4.8.8
Figure 16
Are ramps designed so that water will not accumulate on walking surfaces?
Drains should not be placed on ramps or landings. They can be
located away from the bottom landing and the landing can be sloped slightly toward the
drain to make sure that water drains off and does not puddle.
