Spotting
 Timeline
 Travel Tip
 Trip
 Race
 Social
 Greeting
 Poll
 Img
 PNR
 Pic
 Blog
 News
 Conf TL
 RF Club
 Convention
 Monitor
 Topic
 #
 Rating
 Correct
 Wrong
 Stamp
 PNR Ref
 PNR Req
 Blank PNRs
 HJ
 Vote
 Pred
 @
 FM Alert
 FM Approval
 Pvt
Forum Super Search
 ↓ 
×
HashTag:
Freq Contact:
Member:
Posting Date From:
Posting Date To:
Blog Category:
Train Type:
Train:
Station:
Pic/Vid:   FmT Pic:   FmT Video:
Sort by: Date:     Word Count:     Popularity:     
Public:    Pvt: Monitor:    Topics:    

Search
  Go  
dark mode
 
Thu Mar 28 23:44:08 IST
Home
Trains
ΣChains
Atlas
PNR
Forum
Quiz
Topics
Gallery
News
FAQ
Trips
Login
Post PNRPost BlogAdvanced Search

Blog Entry# 520890
Posted: Sep 06 2012 (11:19)

No Responses Yet
General Travel
3890 views
0

Sep 06 2012 (11:19)  
 
G_I_P_R^~
G_I_P_R^~   7211 blog posts
Entry# 520890              
interesting info from wikipedia.............
DIGITAL AXLE COUNTER
An axle counter is a device on a railway that detects the passing of a train in lieu of the more common track circuit. A counting head (or 'detection point') is installed at each end of the section, and as each axle passes the head at the start of the section, a counter increments. A detection point comprises two independent sensors, therefore the device can detect the direction of a train by the order in which the sensors are passed. As the train passes a similar
...
more...
counting head at the end of the section, the counter decrements. If the net count is evaluated as zero, the section is presumed to be clear for a second train.
This is carried out by safety critical computers called 'evaluators' which are centrally located, with the detection points located at the required sites in the field. The detection points are either connected to the evaluator via dedicated copper cable or via a telecommunications transmission system. This allows the detection points to be located significant distances from the evaluator. This is useful when using centralised interlocking equipment but less so when signalling equipment is distributed at the lineside in equipment cabinets.
Advantages
Unlike track circuits, axle counters do not require insulated rail joints to be installed. This avoids breaking the continuity of long welded rails for insulated joints to be inserted.
Axle counters are particularly useful on electrified railways as they eliminate traction bonding and impedance bonds. Axle counters require no bonding and less cabling in comparison to track circuits, and are therefore generally less expensive to install and maintain.
Axle counters do not suffer problems with railhead contamination, e.g. due to rust or compacted leaf residue, that can affect the correct operation of track circuits.
Axle counters are used in places such as wet tunnels (such as the Severn Tunnel), where ordinary track circuits are unreliable. Axle counters are also useful on steel structures (such as the Forth Bridge), which prevent the normal operation of track circuits. Axle counters are also useful on long sections where several intermediate track circuits may be saved. A Frauscher axle counter sensor, for example, can be 8,500m from the evaluation unit, while the latest ALTPRO axle counter sensor model ZK24 can even go up to 49 km from the unit
Disadvantages
Axle counters may 'forget' how many axles are in a section for various reasons such as a power failure. A manual override is therefore necessary to reset the system. This manual override introduces the human element which may be unreliable. An accident occurred in the Severn Tunnel and is thought to be due to improper restoration of an axle counter. This, however, was not proven during the subsequent inquiry.
Turnouts
Where there are interlocked turnouts, an axle counter unit needs to be provided for each leg of that turnout. On lines with non-interlocked/hand operated switches, detection of the switch points would have to be monitored by a separate system. On track circuited lines misaligned points will automatically break the circuit path.
Fail safety
Axle counters only provide intermittent positive indication of a rail vehicle as it passes a fixed location. If the counter unit fails or becomes disconnected, a train will pass undetected into a block that would otherwise be regarded as unoccupied. Track circuits provide continuous real time detection over a track segment and any loss of power or disconnected wire results in a safe signal indication to the train. Track circuits also allow for the use of clips that instantly shunt the circuit and mark the track as occupied. These can be used by crews or maintenance personnel to quickly report an unsafe condition or mark a section of track out of service. Modern axle counter equipment transmits data from the trackside apparatus to the indoor equipment via telegrams, across an ISDN line. This results in the section of line being monitored showing occupied in the event of persisting technical fault or loss of telegrams. The section then requires a reset command and further interaction to restore to service.
Broken rails
The track circuit provides additional functionality of detecting many, however not all, kinds of broken rails, though only to a limited extent in AC traction areas and not in the common rail in DC traction areas. Axle counters offer no such facility. Ordinary track circuits have a blind spot of about a metre in length from the wiring connections to the insulated joint.
Siding and shunting movements
Axles counters have problems maintaining correct counts when train wheels stop directly on the counter mechanism; this is known as 'wheel rock'. This can prove problematic at stations or other areas where cars are shunted, joined and divided. Also, where main lines have switches to siding, spur or loop tracks extra counters will need to be deployed to detect trains entering or exiting the line, where with track circuits such infrastructure needs no special attention.

Translate to English
Translate to Hindi
Show AI Response

Travel SAFE

1. RailFanning does NOT MEAN dangerous pics/videos.
2. Doorplating pics/youtube videos are strictly FORBIDDEN in IRI.
3. Take plenty of food pics and other safe pics.
4. Write human interest narratives to make the pics interesting.
5. Enjoy blogging and travelling SAFELY.

REMEMBER: YOUR LIFE is the most precious thing, NOT RailFanning.

Rail News

New Trains

Site Announcements

  • Entry# 5648027
    Mar 01 2023 (12:44AM)


    In response to past confusions with Train/Station updates and resulting fights and controversies, the following clear and objective guidelines are being issued, with no room for any arguments or debates about validity. Also, included, some other changes with respect to Ratings. 1. All Red Ratings will require further explanation. Red Ratings won't...
  • Entry# 5388512
    Jun 24 2022 (08:45AM)


    As announced previously, there are a few changes coming to IRI user accounts, based on past practices. 1. As before, you will be able to quickly DELETE your IRI User account at ANY time. However, the menu option for this was hidden in the profile page, and could not easily be located....
  • Entry# 5148000
    Nov 29 2021 (06:40AM)


    A new feature will be released soon, whereby you can follow blogs tagged with specific Trains & Stations. If you have already posted blogs tagged with some Train/Station, then you will be set to automatically follow that Train/Station. Thereafter, any future news/blogs tagged with those Trains/Stations will be marked to your...
  • Entry# 5093784
    Oct 13 2021 (07:04AM)


    These days, every other day, we are getting requests from members to allow email login to their FB-based IRI account. 10 years ago, we had given the option for users to login through FaceBook - in retrospect, this was a mistake. These days, apparently, users are quitting FaceBook in droves because...
  • Entry# 4906979
    Mar 14 2021 (01:12AM)


    Followup to: Fmt Changes The new version of FmT 2.0 will soon be here - in about 2 weeks. As detailed in the previous announcement, many of the old FmT features like Train TT, Speedometer, Geo Location, etc. will be REMOVED. It will be a bare-bones simple app, focused on trip blogging. It...
  • Entry# 4898771
    Mar 06 2021 (10:33PM)


    There are some changes coming to FMT. Many of the features of FMT, like station arrival, TT, speed, geo, passing times, station time, etc. are ALREADY available in OTHER railway apps. So all of these features will be REMOVED. We'll have ONLY BLOGGING - quick upload of pics/videos/audio, etc. You may attach...
Scroll to Top
Scroll to Bottom
Go to Mobile site
Important Note: This website NEVER solicits for Money or Donations. Please beware of anyone requesting/demanding money on behalf of IRI. Thanks.
Disclaimer: This website has NO affiliation with the Government-run site of Indian Railways. This site does NOT claim 100% accuracy of fast-changing Rail Information. YOU are responsible for independently confirming the validity of information through other sources.
India Rail Info Privacy Policy