Given Data Initial Road Design: • Design speed: 85 km/h • • Radius of both circular arcs: R = 845 m = 0.44 m/s³ = 250 m • Rate of gain of radial acceleration on all transitions: q Length of straight section between the curves: Lstr Redesigned Road: New design speed: 120 km/h • New radius: R' = 2500 m 3 Horizontal Alignment An existing road with a design speed of 85 km/h passes from one tangent through a right hand circular arc onto a second tangent, and then through a left hand circular arc onto a third tangent which is parallel to the first. The circular arcs are joined to the straights by clothoid transition curves. Radius of both circular arcs Rate of gain of radial acceleration on all transitions Length of straight between the two curves Length of both circular arcs R q Lstr 250 m a) What is the perpendicular distance between the parallel straight sections? b) Using the same tangents and Intersection Points, the arc radii are increased to 2500m and the transition curves upgraded to a design speed of 120 km/h. How long is the straight section between the two curves after this redesign?
Given Data Initial Road Design: • Design speed: 85 km/h • • Radius of both circular arcs: R = 845 m = 0.44 m/s³ = 250 m • Rate of gain of radial acceleration on all transitions: q Length of straight section between the curves: Lstr Redesigned Road: New design speed: 120 km/h • New radius: R' = 2500 m 3 Horizontal Alignment An existing road with a design speed of 85 km/h passes from one tangent through a right hand circular arc onto a second tangent, and then through a left hand circular arc onto a third tangent which is parallel to the first. The circular arcs are joined to the straights by clothoid transition curves. Radius of both circular arcs Rate of gain of radial acceleration on all transitions Length of straight between the two curves Length of both circular arcs R q Lstr 250 m a) What is the perpendicular distance between the parallel straight sections? b) Using the same tangents and Intersection Points, the arc radii are increased to 2500m and the transition curves upgraded to a design speed of 120 km/h. How long is the straight section between the two curves after this redesign?
Traffic and Highway Engineering
5th Edition
ISBN:9781305156241
Author:Garber, Nicholas J.
Publisher:Garber, Nicholas J.
Chapter15: Geometric Design Of Highway Facilities
Section: Chapter Questions
Problem 21P
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Question
Transcribed Image Text:Given Data
Initial Road Design:
• Design speed: 85 km/h
•
•
Radius of both circular arcs: R
= 845 m
=
0.44 m/s³
= 250 m
•
Rate of gain of radial acceleration on all transitions: q
Length of straight section between the curves: Lstr
Redesigned Road:
New design speed: 120 km/h
• New radius: R'
= 2500 m
Transcribed Image Text:3
Horizontal Alignment
An existing road with a design speed of 85 km/h passes from one tangent through a right hand circular arc
onto a second tangent, and then through a left hand circular arc onto a third tangent which is parallel to
the first. The circular arcs are joined to the straights by clothoid transition curves.
Radius of both circular arcs
Rate of gain of radial acceleration on all transitions
Length of straight between the two curves
Length of both circular arcs
R
q
Lstr
250 m
a) What is the perpendicular distance between the parallel straight sections?
b) Using the same tangents and Intersection Points, the arc radii are increased to 2500m and the
transition curves upgraded to a design speed of 120 km/h. How long is the straight section
between the two curves after this redesign?
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