M2
8
25.40 510
35M
35.7
1000
Federal, state, and local agencies
9
28.65 645
45M
43.7
1500
are already doing metric road and
10
32.25 819
55M
56.4
2500
bridge design, with some already in
11
35.81 1006
or near construction.
14
43.00 1452
18
57.32 2581
Most states have begun converting
standard drawings and specifications
Welded Wire Fabric WRI is currently
to metric. See M1 for details.
developing a series of hard metric wire
diameters. Many firms make their own
See the Road Design Data section for
dies and can make any size diameter.
more detail.
Some firms, mostly those with newer
Right of Way (R/W) Critical issues
variable step spacing equipment such as
appear to be public response to SI,
EVG, Schlotter, or BSG, are able to
and legal acceptance. Our site
produce metric spacing (ex, 150 x 150),
acquisitions, ie r/w purchases,
but minimum orders are significant,
should use technique 1 below, unless
ranging from about
not possible, then use technique 2:
15 Mg to much higher minimum orders.
Look to WRI for shortly forthcoming
1.Hard Metric Only:
100 m
metrication guidance.
2.Hard Metric / Soft English:
100 m
(328.08')
Civil / Roads
With method 2, when SI is used
Road Design States are roughly divided
exclusively, english can be deleted
on use of km or 100 meter stations.
and numbers will be even metric.
AASHTO recommends km stations.
Projects may use either at this time.
This ofcourse applies only to site
acquisitions of uniform geometry
Use AASHTO Standard R1, equal to ASTM
(ex, long stretchs of 100 m wide
E380, for metric practice.
r/w) For site acquisitions of uneven
geometry, SI and english dimensions
Federal Highway Administration directed
will often involve uneven numbers.
that all construction using federal
We use AASHTO 1993 Guide To Metric
funds after October 1996 must be
Conversion, for geometric design
designed using the metric system.
values, lane and shoulder widths,
curb heights, sight distances,
The state response has been decisive in
curvatures, other material. Phone
many areas, as many states have
Orders: AASHTO (202) 624-5800
established dates earlier than that,
setting dates in 1995, after which
Civil / Sitework
their highway construction will be
metric.
Sitework, such as location and
placement of utility feeds, is among
Many major state and local highway
the easier portions of work to do in
projects starting now or in the near
metric. Surveyors already work in
future are being done in metric.
decimal units, and most field
personnel indicated switching to
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