Forums Search/Statistics.
Track Forum07/02 19:09
Brainstorming for 2nd Phase Track Modernisation06/02 13:27
Rly Bridge Forum08/02 09:05
General Forum08/02 09:16
Works Forum05/02 18:18
Track Machine Forum06/02 13:37
ROB/RUB/LXING Forum01/02 22:48
Track Procurement Forum04/02 06:51
 How to use RSS
Warning: Cannot modify header information - headers already sent by (output started at /var/www/html/IRICEN1/themes/fisubsilversh/theme.php:138) in /var/www/html/IRICEN1/includes/sessions.php on line 249 Warning: Cannot modify header information - headers already sent by (output started at /var/www/html/IRICEN1/themes/fisubsilversh/theme.php:138) in /var/www/html/IRICEN1/includes/sessions.php on line 250
Indian Railways Institute of Civil Engineering: Forums

Warning: Cannot modify header information - headers already sent by (output started at /var/www/html/IRICEN1/themes/fisubsilversh/theme.php:138) in /var/www/html/IRICEN1/includes/page_header.php on line 477 Warning: Cannot modify header information - headers already sent by (output started at /var/www/html/IRICEN1/themes/fisubsilversh/theme.php:138) in /var/www/html/IRICEN1/includes/page_header.php on line 479 Warning: Cannot modify header information - headers already sent by (output started at /var/www/html/IRICEN1/themes/fisubsilversh/theme.php:138) in /var/www/html/IRICEN1/includes/page_header.php on line 480
 
Post new topicReply to topic
View previous topic View next topic
Author Message

Shivyogi Hiremath
Assistant Manager

View user's profile
Shared Documents

Joined: Aug 27, 2012
No. of
Replies: 9

PostPosted: Tue Aug 11, 2015 12:19 pm Back to top

Sir, why is degree of curve is defined by using "30.5m"[/b] chord length, which comes out be D=1750/R. Please explain.
Also please tell me if radius is changing in tarnsition portion, why do we calculate speed taken a single value of radius.
            
            
            
- Shivyogi Hiremath Graduate Engineer Trainee ... 11-08-15

MOHAMMAD BAKHSH
Rtd. Dy Chief Engineer

View user's profile
Shared Documents

Joined:
No. of
Replies: 1144

PostPosted: Tue Aug 11, 2015 1:26 pm Back to top

A circular curve is specified by its radius or degree. A small circle is easily laid out by using the radius. In a mathematical sense, the curvature is the reciprocal of the radius, so that a smaller curvature implies a large radius. A curve of large radius, as for a railway, cannot be laid out by using the radius directly.
As for speed the introduction of the circular curve at the PC takes place at a point but drivers and vehicles do not make directional changes instantaneously.
A solution is to introduce both the curvature and super elevation at a gradual rate using an easement curve or transition curve that gradually changes in radius from infinity to some finite value where the associated circular curve begins. In short,a transition curve is required.
The speed is therefore defined relating to Degree of curve or radius.
            
            
            
- MOHAMMAD BAKHSH  Rtd. Dy Chief Engineer ... 11-08-15

Shivyogi Hiremath
Assistant Manager

View user's profile
Shared Documents

Joined: Aug 27, 2012
No. of
Replies: 9

PostPosted: Tue Aug 11, 2015 4:28 pm Back to top

Sir , thank you for the infomartion. I understand that sir, but sir why 30.5m is choosen, why not 100m chord, or 50m chord for defining degree of curve
            
            
            
- Shivyogi Hiremath Assistant Manager ... 11-08-15

Abu Hasan
SSE/TM/NFR

View user's profile
Shared Documents

Joined: Feb 09, 2008
No. of
Replies: 46

PostPosted: Tue Aug 11, 2015 4:46 pm Back to top

Respected Sir,
It is exactly in the same way you are thinking. British used it as 100 feet i. e. 30.5m.
            
            
            
- Abu Hasan SSE/TM/NFR ... 11-08-15

Ramamurthy C
Railway Track Design Engineer

View user's profile
Shared Documents

Joined: May 31, 2006
No. of
Replies: 145

PostPosted: Tue Aug 11, 2015 7:16 pm Back to top

As Mr Hasan has mentioned, the value comes from FPS units. Degree of curve is defined in FPS units as the angle subtended at the centre of a curve by an arc of 100 feet. 100 feet is nearly equal to 30.5 m.
            
            
            
- Ramamurthy C Railway Track Design Engineer ... 11-08-15

MOHAMMAD BAKHSH
Rtd. Dy Chief Engineer

View user's profile
Shared Documents

Joined:
No. of
Replies: 1144

PostPosted: Wed Aug 12, 2015 12:15 pm Back to top

The degree of curvature is customarily defined as the central angle subtended by a chord of 100 feet or,30.50M. It is easy to stretch one tap length of 100 feet or 30.5M.The MKS or CGS was adopted very late in India.The easiness of handling one tap length paved the way for using one tap length which is 30.5 M.
            
            
            
- MOHAMMAD BAKHSH  Rtd. Dy Chief Engineer ... 12-08-15

Shivyogi Hiremath
Assistant Manager

View user's profile
Shared Documents

Joined: Aug 27, 2012
No. of
Replies: 9

PostPosted: Wed Aug 12, 2015 1:05 pm Back to top

Thank you all
            
            
            
- Shivyogi Hiremath Assistant Manager ... 12-08-15
Display posts from previous:      
Post new topicReply to topic
View previous topic View next topic
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum