|Standard Span Configuration of ROBs. RDSO Letter No CBS/DRO Dated 15.04.2010|
|Standard Spans for Composite ROBs. Enclosed with RDSO Letter No CBS/DRO Dated 15.04.2010|
Government of India-Ministry of Railways
Research Designs & Standards Organisation
Manak Nagar, Lucknow- 226011
Telefax : 0522-2450398
Sub: Guide Lines for Configuration of standard arrangement for composite steel girder ROBs
- Railway Board’s letter No.2002/CE-I/BRO/64(Policy) dated 17.7.2009
- Railway Board’s letter No.2002/CE-I/BRO/194(Design) dated 10-11-2009
With a development of road network and increase in traffic both on roads as well as Railways, the requirement of providing ROBs have increased many fold in recent years. It is observed that different Railways are following different configurations for ROBs which require duplication of efforts and the projects are delayed.
A need was being felt for quite some time to standardize the span arrangement and issue standard designs for steel composite girders so that the planning and design efforts by various railways are reduced and work can be done faster. Certain other advantages of steel composite girders are:
i) Fabrication can be done in work shop with good QC.
ii) No temporary staging and continued speed restriction required.
iii) Light weight and therefore easy, fast and safer method of launching.
iv) Very fast construction can be achieved.
v) Easy to dismantle if required and re-use the steel girder. Board (ME) vide ref.(ii) above, decided that RDSO in association with W.Rly should finalise the configuration and standard drawings for composite girders of ROBs. The suggestions were collected from other railways also and standard composite steel girders for various spans have been finalised which will cater most of the situation for planning of ROB. Standard depth and spacing of composite steel girders for various spans are given in table below:
|Span||C/C of bearings||Square Spacing of girders||Total no. of tracks including future tracks||Depth of Steel Girder||Total depth including deck slab|
|18m||2.50 m||3||1.20 m||1.60 m|
|24m||2.50 m||4||1.50 m||1.90 m|
|30m||2.50 m||5||1.90 m||2.30 m|
|36m||2.50 m||6||2.20 m||2.60 m|
These spans are suitable for square spans and can also cater for skew angle crossing up to 20 deg , when above length are taken as skew span. These spans may be suitable for higher skew crossings also with specific consideration in design of deck slab & bracing arrangements. The width of deck slab should be kept as per requirement of the Road width, foot paths, crash barriers, etc.. The number of girders required for can be decided keeping max. center to center distance in square as 2.5 m and maximum overhang of slab as 1.0m. Some salient features are given as under:
i. These girders are welded type.
ii. End diaphragm girders should be provided along the alignment of the bearing so that the entire span at one end can be lifted with help of synchronous jacks for attending bearings etc.. Cross bracing should be provided squire to the girder alignment.
iii. All field joints of cross bracings and end diaphragms are planned with High Strength Friction Grip Bolts.
iv. Stud type/ flexible shear connectors are provided. Rigid shear connectors of structural steel section welded on top flange should not be provided.
v. The in situ concrete slabs of M-35 shall be provided.
vi. The top of pile cap should be planned not above formation level and bottom of pile cap should not be planned below the slope line of 1:1 from the edge of the sleepers.
vii. Provision of Abutment/pier at railway boundary is not mandatory. Standard span should be planned over the railway track. Adjacent spans can also be of required standard span .
viii. GAD for skew crossing may be planned with skew angle in increment of 5 deg.. Normally the skew angle more than 45 degree should be avoided. However any skew angle can be provided with approval of CBE if unavoidable.
ix. The G.A.D should be prepared carefully to fit in above standard span girders. In case of higher skew crossings, next higher standard span can be used. For an example a 24.0 m skew span can be used for crossing three tracks up to 45 deg. skew angle.
x. The pier can be circular or of wall type parallel to the track. At abutment also piers type structure can be provided with wall of Reinforced Earth work in the back. Typical plans and elevation for various span are enclosed for guidance , which have been made to cover most of the cases. Still comment and suggestions for improvement are requested so that same can be incorporated while issuing the drawings. The suggestions if any may be sent positively by 15.05.2010.
Zonal Railways may plan their ROB works as per above guidelines and confirmation of same may be advised to this office as well as EDCE/B&S-II, Railway Board for perusal of Board. These guidelines have been pasted on IRICEN’s website as well as on RDSO website along with all the Annexures. The hard copy will also be sent to all the Zonal Railways.
No 2007/CE I/LX/90
Main policy issues relating to Level Crossings and ROB/RUBs
PROVISION OF NEW LEVEL CROSSING
As per existing policy, provision of level crossing is made in consultation with the State Govt. at the time of laying a new line or within 10 years from the date of its commissioning to traffic. Thereafter any accommodation work such as level crossing can be provided at suitable location on ‘Deposit Terms’ basis, if such a proposal is sponsored by the State Govt./Local Bodies duly agreeing to bear the initial cost of construction of the levelcrossing and one time capitalized cost of recurring maintenance and operational charges. Further, as per current policy of Railways, no new unmanned level crossing is permitted on existing lines.
MANNING OF EXISTING UNMANNED LEVEL CROSSING
As per extant rules, in case an unmanned level crossing provided initially and maintained at the cost of the Railways, needs manning/upgrading/posting of additional gatekeeper due to increase in road traffic only, the cost both initial as well as recurring and maintenance has to be borne by the State Government/Road Authority concerned. However, keeping in view the grave consequences of accidents at unmanned level crossings, Railways have decided in 2003 to man vulnerable level crossings based on the traffic volume and visibility conditions at the unmanned level crossings for which Railways have laid down certain criteria based on traffic volumes and visibility conditions. Manning of such level crossings is being done progressively.
WIDENING OF LEVEL CROSSINGS
The width of the level crossings depend on the type and width of the road on which it is located. Such level crossings are widened as and when the width of the road is increased by the State Govt./National Highway Authority of India
CONSTRUCTION OF ROAD OVER/UNDER BRIDGES
A. Cost Sharing
Road Over/Under Bridges works are undertaken by Railways in lieu of existing level crossings on cost sharing basis if the traffic density at the level crossing is one lakh or more TVUs (TVU- a unit obtained by multiplying the number of trains to the number of road vehicles passing over the level crossing in 24 hours) otherwise on ‘Deposit Terms’ basis. Proposals are sponsored by State Govt. concerned duly fulfilling certain pre requisites required under extant rules. State Government/Road Authorities sponsor the proposal by completing pre-requisite formalities like:
i) undertaking for closing of the Level Crossings,
ii) provision of funds in the State’s Budget and
iii) Advance action for land acquisition etc.
Cost of Land is borne by State Government. State Government/Road Authorities may also raise their share cost through collection of toll, commercial exploitation of space under Road Over Bridges out side the railway boundary, etc.
CLOSURE OF LEVEL CROSSING IN LIEU OF WHICH ROAD OVER/UNDER BRIDGE HAS BEEN CONSTRUCTED.
As per standard condition of agreements entered into with the State Govts. prior to sanction of work for replacement of an existing level crossing with Road Over/Under Bridges, the State Govts. are liable to give an undertaking that the level crossing in lieu of which the Road Over/Under Bridge is being sanctioned on cost sharing basis, will be closed on commissioning of the Road Over/Under Bridge. Therefore, on commissioning of the Road Over/Under Bridge to traffic, the level crossing in lieu of which it is constructed on cost sharing basis is closed.
Construction of ROB/RUBs in lieu of existing level crossings which have traffic density of less than 1 lakh TVUs is considered on ‘Deposit’ Terms, proposal for which is sponsored by concerned State Govt. duly agreeing to bear the entire cost of construction and recurring maintenance charges thereof. Similarly ROBs at new places where no level crossing exists’ are also provided on ‘Deposit’ Terms.
Construction of ROB/RUBs on BOT(Built, Operate & Transfer) Scheme can be done in agreement by State Govt. by allowing private parties to construct ROB/RUBs and recover their capital in resurrect by charging fee from users of ROB/RUBs. This was agreed to in Nov’94 in terms of National Highway Act 956 section VII & IX as amendment vide Ordinance promulgated by President of India on 23 rd Oct 1992.
ROB related issues
i) Railways share 50% cost of the total work for a two lane Road Over Bridge i.e. 7.5 meter wide carriage way with 2 footpath of 1.5 meter width on either side. However, if Railway desires to have extra length of the bridge to accommodate future tracks, the cost of the extra length is to be borne by the Railways, in addition to their share. In case State Govt./authorities desire extended length of approaches, the cost shall be borne by them.
ii) For National Highways, the Road width shall be 9.5 meters with two raised kerbs of 0.75 meter, or 7.8 meter with two foot paths 1.5 m each on either side or crash barriers as per stipulations and requirements of Ministry of Road Transport and Highways (MRTH). The Railway will bear the entire cost of bridge proper across tracks and cost of approaches will be borne by MOSRTH/National Highway wing of State Govt. irrespective of land boundaries.
iii) A policy was issued in 1991 as per which now Railways also share 50% cost of the RUB/sub-way for light vehicles if provided in addition to the cost of Road Over Bridge. This has been done to enable State Governments to close the Level Crossings without any problems.
RECENT INITIATIVES REGARDING CONSTRUCTION OF ROAD OVER/UNDER BRIDGES ON COST SHARING BASIS:
Recently, following initiatives have been taken by the Ministry of Railways to encourage construction of Road Over/Under Bridges in lieu of busy level crossings.
i) Sharing of cost for four lane ROBs/RUBs
• Since Jan 2003, Rly. shares 50% cost of 4 lane ROB/RUB provided minimum TVU of the level crossing is 3 lakhs comprising not less than 6000 road vehicle units.
• And, Road Authority agree for the four laning of the approach portion also.
ii) Sharing cost of widening of two lane existing Road Over/Under Bridges
• Since Jan 2003, Rly shares 50% cost of widening of existing two lane ROBs/RUBs to four lane Road Over/Under Bridges also, provided, that the TVU level is not less than 5 lakh comprising not less than 10,000 road vehicle units.
• In addition, an incremental increase of two lakh TVUs comprising 4000 road vehicle units must have taken place since the construction of the two lane Road Over Bridge.
iii) Sharing of cost of Road Over Bridge where State Govt. can raise their share through commercial means.
• Since May 2002, Railways share 50% cost of the ROB where State Govt. may raises its 50% share through commercial means like collection of toll or commercial utilization of space under the ROB outside the Railway land.
iv) Standardization of width of ROB/RUB as per latest MRTH norms
• Since Sept. 2002, Railways agreed to share as per the latest norms of MRTH for National Highways ROB width as 9.5 m with two raised curbs of 0.75 m or 7.8m with two foot path each on either side or crash barriers. Sanctioned ROB/RUBs Works on Cost Sharing Basis