Transportation Engineering and Planning [3 ed.] 0131973096, 9780131973091

Citation preview

\· .

Transport;ation Engineering and Planning Third Edition

C. S. Papacostas P. D. Prevedouros University of Hawaii at Manoa Honolulu, Hawaii

·PHI Learning .[;lcrfmm08 ~oWJo088 New Delhi-11 0001 . 2009

This Indian Reprint-Rs. 395.00 (Original U.S. Edition-Rs. 3260.00) TRANSPORTATION ENGINEERING AND PLANNING, 3rd ed. by C.S. Papacostas and P.O. Prevedouros Original edition, entitled Transportation Engineering and Planning, 3rd ed. by C.S. Papacostas and P.O. Prevedouros, published by Pearson Education, Inc., publishing as Pearson Prentice HaiL Copyright© 2001 Pearson Education !nc., Upper Saddle River, New Jersey 07458, U.S.A. ISBN-978-81·203-2154-0 All rights reserved. No part of this book may be reproduced- or transmitted in any form or by any

means, electronic or mechanical, including photocopying, recording or by any information stor\)l..

~--

- •'>..

I

.L

Q

Cit,ies:andTnwns

Collectors Locals

I"'

I

LEGEND

o Village . _ _ _ Arterials

I

~

• I

-·0

1'""1' 1'( •;"'!"' ...

.. 'F" 'i"'!'

__L A

,.. I-'-

1..1. ·- ,;.. ..J ..

·-

"' -'Q· LEGEND

Arterial Street Commercial Area Local Street 11111111.1 Collector Street Public Area

Figure 2.4.2

Illustration of funCtionally classified highways. (From A Policy on Geometric Design of.fiighways and Streets, Copyright 1990,.by the American Association of State Highway and Transportation Offlcials, Washington, DC [2.2) (Figs: 1-3 alld 1-4, pp. 7-8.) Copyri'ght · 1990. Used with permission.)

2.4.3 Cross-Secti_on Design Cross-section desigu refers to the profile of the facility that is perpendicular to the centerline and extends to the limits of the right-of-way within which the facility is constructed. Figure 2.4.3 illustrates the cross section of a typical undivided two-lane rural highway with a lane in each direction of travel. Lane separation is designated by longitudinal pa~ement ·

Roadway Design

46·,

Figure 2.4.3

Chap.2

Cross section of a two-lane rural highway. (From A Pulicy on Geometric Desifln 1~[ HiRlnvoys and Streets. Copyright !990, by the American Association of State Highway and Transportati6n Officials., Washington, DC [2.2] (Fig. VH-1, p. 501.) Copyright 1990. Used by penl}ission.}

markings. A normal crown, that is, a mild slope in the pavement on either side of the centerline, is provided to facilitate the removal of water. Depending on drainage requirements, crOwnS in the range of~ to about! in./ft of width are typic~!. Payed or unpaved shoulders are provided at either end of the travel-way pavement for emergency situations. Beybnd the

· shoulders. drainage ditches are provided with cut or filled side slopes at appropriate angles to ensure slope stability. Figure 2AA shows typical types of divided multilane rural highways. The separation of the two directions of .travel may be accomplished by constructing independent roadways and by utilizing raised or depressed inedians. Various types of har6er.v (including guardrails and concrete barriers) may be used along the median and at- the-end or the clear zone beyOnd the shoulders. Depending on their function, urban facilities may also be either undivided or divided. Urban roadways often incorporate draihage ditches or gutters ;1nd raised curbs. Urban arterials can be at ground level (i.e., at grade), elevated, .or depressed: they may also cohtain special bus lanes and rail-transit ways within their rights-of-way.

2.4.4 Horizontal Alignment

'

The horizontal alig,~me_nt of a hi'ghway, railway, or transit gu-ideway represents the projection of the facility on a horizontal plane.Jt generally-consists of straight-line segments (tangents) connected by circular-cu-rves either directly (simple curl'.e.\·) or via intenncdia:te transition curves. Figure 2.4.5 illustra-tes these two_common -geometric arra·ngements. The length of the facility is measured along the horizontal alignment of a control line. such, as the centerline of a highway, and is us-Ually expressed in terms of 100-ft stations from a reference point. Thus a point On the alignment designated as sta. 14 is located at a distance of 14 stations (i,e .• 14 X 100 = 1400 ft)from the reference point. Similarly. a point identified as sta. 14 + 56.70 is located at a·distance'of 1456.70 ft from the ,:cfef' ence point. . ~' . . . . Figu.re 2.4.6 shows the horizontal alignment' the centerline of a simple curve. A simple circular curve connects two tangents, whiCflWfieO. prOjected meet at apoim r~{imi:r­ sectiOft, or PI. Proc.eeding in the direction of increasing station values, point A is designated ·as the point.of curvature (PC). that is, the point wh~re the curve begins. Point B. or the end of. the curve, iS denoted as the point C?f'tein'gency, or PT. At these two poi.nts, of course. the radii ofthe circular curve'are perpendicular to the tangents. The length of the curve AB equals

of

I

1

Design and Operation

Par:t 1 R.O.W.

1

j

R.O.W.

325'- 375' "

r·~50'- 80'

47

150' +

·-milO' 24' . !

24' 10'

50'- 80'

--+--~~-+1___::~-

e:,_..-LLLLl.--i=:=f,-..___

i

(a) Independent roadway

R.O.W

200'- 250'

RO.W

:!:::

40'- 50'

(b) Typical

R.f).W. 150'-175':!:: :.::__::.::._..:=__ _ _ _ _ _ _ _ _ _ _ _ I!

R.O.W

3Q' 40'

1

lQ~

24'

,

lQ' · 3Q'

24'

i

10'

!

30'- 40'

~

~--_:--+]1··- ~---~·f.

(2.4.4)

D

2.4.5 Determination of Design Radius The requirement for lateral banking or superelevating the cross section of curved paths (discussed in Section 2.2.3) imposes a constraint on the minimum radius that the curve may have. Equation 2.2.19 (reproduced as Eq. 2.4.5) expresses the relationship among the superelevation rate e, the design speed v, the coefficient of side frictionfs, and the curve radius R: (2.4.5) An alternative specification of this formula found in U.S. design manuals is the following mixed-unit equation:

.I

I

vz

e+f'=-.' JSR

(2.4.6)

where the design speed has yJJ.its of miles per hour (mi/h) and the radius is specified in feet (ft).

100ft

________ 7 ____ _ 100ft

i

I 1.

\ D

D

(a) Arc definition Figure 2.4.7

(b) Chord definition Degree of curve.

Part 1

I

Design and Operation

The maximum allowable design value fore [2.2] is 0.12 ft/ft and the suggested max-imum-iS set at 0.10, but, special con L · (a)'Crest

---L---~ S: