正确《交通工程专业英语翻译》

2021年1月21日发(作者：粗人)

Design of the Alignment
线形设计


The
alignment
of
a
highway
is
composed
of
vertical
and
horizontal
elements.
The
vertical
alignment includes straight (tangent) highway grades and the parabolic curves that connect these
grades. The horizontal alignment includes the straight (tangent) sections of the roadway and the
circular curves that connect their change in direction.



公路线形包括平曲线和竖曲线元素。
竖曲线包括直坡线
（切线）
和连接这些直坡线的抛物线。
平曲线包括公路的直线部分（ 切线）和连接两直线并转向的圆曲线。



The design of the alignment depends primarily on the design speed selected for the highway. The
least
costly
alignment
is
one
that
generally
takes
the
form
of
the
natural
topography.
It
is
not
always
possible
to
select
the
lowest
cost
alternative
because
the
designer
has
to
adhere
to
certain standards that may not exist on the natural topography.



线形的设计取决于公路的设计速度。
最经济的线形是沿着自然地形展线。
现 实中设计师
往往不能选择造价最低的方案，
因为他们必须遵循特定的技术标准，
而这些 标准在自然地形
中也许难以达到。



It
is
important
that
the
alignment
of
a
given
section
has
consistent
standards
to
avoid
sudden changes in the vertical and horizontal layout of the highway. It is also important that both
horizontal and vertical alignments be designed to complement each other, since this will result in
a safer and more attractive highway.



重要的是给定部分的线形必须符合规范来避免公路在水平和竖直布局上 产生突变。
同样重要
的是设计的平曲线和竖曲线要相互协调，因为这样才能设计出安全并更有吸 引力的公路。



One
factor
that
should
be
considered
to
achieve
compatibility
is
the
proper
balancing
of
the
grades of tangents with curvatures of horizontal curves and the location of horizontal and vertical
curves
with
respect
to
each
other.
For
example,
a
design
that
achieves
horizontal
curves
with
large radii at the expense of steep or long grades is a poor design. Similarly, if sharp horizontal
curves are placed at or near the top of pronounced crest vertical curves or at or near the bottom
of a pronounced sag vertical curve, a hazardous condition will be created at these sections of the
highway.
Thus,
it
is
important
that
coordination
of
the
vertical
and
horizontal
alignments
be
considered at the early stages of preliminary design.


为提高协调性应考虑的因素之一是保持直线坡度和曲线曲率均衡 ，
处理好平曲线和竖曲
线之间的相互位置。
例如，大半径平曲线搭配长陡纵坡是一种较 差的设计。
同样，
如果在凸
形竖曲线的顶部及附近或在凹形竖曲线底部及附近设置小半 径平曲线，
那该路段就会变得很
危险。因此，在初步设计阶段综合考虑平纵曲线很重要。


The
vertical
alignment
of
a
highway
consists
of
straight
sections
known
as
grades,
or
tangents,
connected
by
vertical
curves.
The
design
of
the
vertical
alignment
therefore
involves
the selection of suitable grades for the tangent sections and the appropriate length of the vertical
curves. The topography of the area through which the road traverses has a significant impact on
the design of the vertical alignment.


公路竖曲线由纵坡线或称切线以及连 接他们的竖曲线组成。
因而，
竖曲线的设计包括直
线合适坡度的选择和竖曲线合适长度 的设计。
路线所穿越地区的地形对竖曲线的设计有十分
重要的影响。



The effect of grade on the performance of heavy vehicles must be considered. The speed of
a
heavy
vehicle
can
be
significantly
reduced
if
the
grade
is
steep
and/or
long. Note
that
steep
grades not only affect the performance of heavy vehicles but also the performance of passenger
cars.
In
order
to
limit
the
effect
of
grades
on vehicular
operation,
the
maximum
grade
on
any
highway should be selected judiciously.


必须考虑到纵坡对重载交通的影响。如果纵坡很陡且
/
或很长，重交通车辆 的车速将极大地
降低。
注意到坡度不仅影响重车的性能同时也影响轿车的性能。
为限制 纵坡对车辆运行的影
响，任何公路都应恰当的选择最大坡度。



The
selection
of
maximum grades
for
a
highway
depends
on
the
design
speed
and
the
design
vehicle. It is generally accepted that grades of 4 to 5 percent have little or no effect on passenger
cars, except for those with high weight/horsepower ratios, such as those found in compact and
subcompact
cars.
As
the
grade
increases
above
5
percent,
however,
speeds
of
passenger
cars
decrease on upgradesand increase on downgrades.


公路最大坡度的选择取决于 设计速度和设计车辆。
普遍认为
4%-5%
的坡度对客车的影响不大
或没有影 响，除非是（质量
/
功率）较高的车，例如那些小型车或微型车。然而，当坡度大
于< br>5%
时，客车上坡速度进一步降低，下坡速度进一步增加。



Grade
has
a
greater
impact
on
trucks
than
passenger
cars.
Extensive
studies
have
been
conducted,
and
results
have
shown
that
truck
speed
may
increase
up
to
5
percent
on
downgraded and decrease by 7 percent on upgrades, depending on the percent and length of the
grade.


坡度对卡车的影响大于客车。进行了广泛研究， 其结果表明卡车下坡时速度增加超过
5%
，
上坡时速度降低超过
7%
，取决于坡度和坡长。



Maximum
grades
have
been
established,
based
cm
the
operating
characteristics
of
the
design
vehicle on the highway. These vary from 5 percent for a design speed of 70mi/h to between 7
and 12 percent for a design speed of 30 mi/h, depending on the type of highway. Note that the
recommended maximum grades should not be used frequently, particularly when grades are long
and the traffic includes a high percentage of trucks. On the other hand, when grade lengths are
less
than
500
ft
and
roads
are
one-way
in
the
downgrade
direction,
maximum
grades
may
be
increased by up to 2 percent, particularly on low-volume rural highways.


最大坡度根据设计时就已确定的公路上汽车操控特点确定。
按公路类型不同，
最大坡度从设
计速度
70
英里
/
小时的
5%
到设 计速度
30
英里
/
小时的
7%-12%
不等。
注意 到推荐最大坡度不
能频繁使用，尤其是纵坡较长而且车辆中卡车百分比较大时。另一方面，当坡长不足< br>500
英尺而且是下坡路段单行道时，最大纵坡可以增加超过
2%
，尤其在交通 量小的乡村公路。



Minimum grades depend on the drainage conditions of the highway. Zero- percent grades may be
used
on
uncurbed
pavements
with
adequate
cross
slopes
to
laterally
drain
the
surface
water.
Whenpavements are curbed, however, a longitudinal grade should be provided to facilitate the
longitudinal flow of the surface water. It is customary to use a minimum of 0. 5 percent in such
cases,
although
this
may
be
reduced
to
0.3
percent
on
high-type
pavement
constructed
on
suitably crowned, firm ground.


最小坡度取决于公路排水条件。
零坡可以用于不受限的有适当路拱横坡来排干路表水的
路面。
然而，
当路面受 限制时，
纵坡应能促进路表水的纵向流动。
这种情况下通常采用
0.5%
的最 小纵坡，而在有合适铺装、周围硬化的高等级路面中可能减至
0.3%
。



Vertical curves are used to provide a gradual change from one tangent grade to another so
that vehicles may run smoothly as they traverse the highway. These curves are usually parabolic
in shape. The expressions developed for minimum lengths of vertical curves are therefore based
on the properties of a parabola. They are classified as crest vertical curves or sag vertical curves.


竖曲线通常 用来使路线从一个坡度到另一个坡度的平缓过渡，
这样在车辆穿越公路的时候可
以平顺地行驶。
这些曲线通常是抛物线形的。
竖曲线最小长度公式取决于抛物线的性质。
竖
曲 线又分为凹形竖曲线和凸形竖曲线。



The main criteria used for designing vertical curves are: (1) provision of minimum stopping sight
distance;(2) adequate drainage; (3) comfortable in operation; (4) pleasant appearance. The first
criterion is the only criterion associated with crest vertical curves, whereas all four criteria are
associated with sag vertical curves.

设计竖曲线的主要标准包括：
（
1
）停车视距的 要求；
（
2
）充分考虑排水要求；
（
3
）行车
舒适 性要求；
（
4
）
路线美观要求。凸形竖曲线只与第一个条件有关，而凹形竖曲 线与四个条
件都有关。



The
horizontal
alignment
consists
of
straight
sections
of
the
road
(known
as
tangents)
connected by horizontal curves. The curves are usually segments of circles, which have radii that
will
provide
for
a
smooth
flow
of
traffic.
The
design
of
the
horizontal
alignment
entails
the
determination
of
the
minimum
radius,
the
determination
of
the
length
of
the
curve,
and
the
computation
of
the
horizontal
offsets
from
the
tangents
to
the
curve
to
facilitate
locating
the
curve in the field. In some cases, to avoid a sudden change from a tangent with infinite radius to
a curve of finite radius, a curve with radii varying from infinite to the radius of the circular curve is
placed between the circular curve and the tangent. Such a curve is known as a spiral or transition
curve. There are four types of horizontal curves: simple, compound, reversed, and spiral.


平面线形由公路的直线部分和连 接它的平曲线组成。
平曲线通常是圆曲线段组成的，
圆曲线