1.PRESENTED BYJayvant choudhary M.Tech (Ist sem) Transportation engineering

2. Railway crossing however adequately designed are accident prone ,but they are adopted at the places where it is not possible from engineering and economic consideration to provide road over/under bridge.Should be located away from railway station and marshalling yards. if unavoidable then should be located beyond shunting limits. 3. Special A class B class C class D classCLASS INH SHFor Vehicular trafficFor cattle crossing and footpathsCLASS IICLASS IIICLASS IVODR,MDR Un imp road within townsImp roads within townsRoads within non municipal townsRoads in and around town where traffic is heavyOther surfaced roadsEarth roadsCart tracksCattle crossing and footpaths 4. BETWEEN GATES: CLASS ICLASS IICLASS IIICLASS IV9 m or equal to width of carriageway immediately outside gate plus 2.5 m 7.5 m or equal to width of carriageway immediately outside gate plus 2 m 5 m or equal to width of carriageway immediately outside gate plus 1.25 m Minimum of 2mWhichever is more 5. OUTSIDE GATES CLASS ICLASS IICLASS IIICLASS IV7 m or equal to width of existing carriageway5.5 m or equal to width of existing carriageway 3.75 m or equal to width of existing carriagewayWhichever is moreMinimum of 2mNote : the width immediate carriageway tapers down to existing carriageway within distance of 30 m from gate 6. Between gates : surface shall not be of lower standard than surface outside the railway boundary. in case of cement concrete surface black topped surface may be provided Outside gates: surface shall not be of lower specification than that of existing road however in case of class I and class II roads black topped surface should be provided for distance of at least 30 m from gatesGates employed are: 1)Swing gates 2) Lifting gates 3)Movables barriers of approved designs Gates should be at right angle to centre line of road 7. Minimum distance of gates from centre line of nearest railway track should be 3 m on BG lines and 2.5 m on MG & NG lines.Angle of crossing between centre line of railway track and road- it should not be less than 45 degrees in case of Class I,II,III roads(lower than 45 degrees can also be provided only after special permission by railway board). for class IV roads angle of crossing should be 90 degrees 8. It depends upon the design speed, coefficient of friction between tyres and road surface and max allowable value of superelevation.As per IRC:39-1986 following values should be adopted 9. BETWEEN GATES :-level for all classes OUTSIDE GATES:A) Class I roads-same level as between the gates upto 15 m beyond And not steeper than 1 in 40 beyond B)Class II roads:-same level as gate upto 8 m beyond gates and not steeper than 1 in 30 beyond C)Class III roads-same level as between the gates upto 8 m beyond gates and not steeper than 1 in 20 beyond D)Class IV roads:-not steeper than 1 in 15 10. CLASS I CLASS IICLASS III CLASS IVShall be provided for pedestrian except where there are foot over bridgesWicket gates should be such manner so that cattle can not easily and readily pass Need not to through them be providedWicket gate 11. UNGUARDED CROSSING The distance of second sign from crossingAn advance warning sign located at 200m 50-100 30from crossing m for 60m plain for hilly and terrain rolling terrainGUARDED CROSSING The distance of second sign from crossingAn advance warning sign located at 200m 50-100 30from crossing m for 60m plain for hilly and terrain rolling terrain 12. Gates should be painted white,with a red disc not less than 60 cm in diameter in centre.the gate posts also be painted white 13. LIGHT AS OBSERVED BY ROAD USERS CLASS I & II roads Red when either gate is closed to road White when gates are openedCLASS III roads Same as that of class I and II roads but reflector may used as alternate of lampsLIGHTS AS OBSERVED BY DRIVERS OF APPROACHING TRAINS Class I roads Red when get closed across railway trackOther casesnil 14. 1. Latest IRC road sign indicating whether the railway crossing is manned or unmanned shall be installed on either end at prescribed distance as per IRC:67-1977 2. Speed limit road signs should be installed on either of gates 3. Speed breakers shall not be permitted4. Flashing signals shall be installed on both sides of crossing after assessing their requirementsFlashing signals 15. A kilometer stone is one of a series of numbered markers placed along a road or boundary at intervals of one km or occasionally, parts of a km. They are typically located at the side of the road or in a median Kilometer stones are constructed to provide reference points along the road. This can be used to reassure travellers that the proper path is being followed, and to indicate either distance travelled or the remaining distance to a destination 16. FOR NH,SH,& MDR:- The stones are of two sizes 1. Ordinary kilometer stone(small size) 2. Fifth kilometer stone(bigger size)ORDINARY KILOMETER STONESSIDE ELEVATIONFRONT ELEVATIONEXAMPLE 17. FIFTH KILOMETER STONEFRONT ELEVATIONSIDE ELEVATIONEXAMPLE 18. FOR O.D.R &V.R:-Plate 3 In I ILOCALLY AVAILABLE MATERIAL SUCH AS HARD STONE , CEMENT CONCRETE ETC 19. Ordinary km stone shall be inscribed in hindi or in local language & indicate name & distance to the next imp town or terminal station Fifth km stone can be inscribed only in roman and show the distance of terminal as well as intermediate station The place name shall be inscribed in different script in following sequence 20. On each kilometer stone its number shall be inscribed on side of stone facing the carriage way.This numbering is meant for maintenance staff and will start with zero at starting stationLetters and numerals shall be of following size 21. Chart provided in IRC:8-1980 give dimensions of the letters and numerals 22. Spacing between the standard letters or numerals are also provided in IRC:8-1980 as follows 23. Edge clearance should be given asBackground colour should be white with black letter and numerals Semicircular portion should be painted canary yellow (I.S.Shade 309) on NH,brilliant green on SH and white on MDR Route numbers written should be of black colour on canary yellow and white on green background 24. Normally kilometer stone are placed on left hand side of road On divided roads having central median they should be provided on both sides of road Kilometer stone shall be fixed at right angle to centre line of carriageway On embankment they shall be located on edge of roadway beyond shoulder 25. MATERIAL-locally available materials such as hard stone ,well dressed or of reinforced cement concrete LOCATION & SPACING- they should be fixed on either side of road land opposite every 200 meter stone. In addition they shall be fixed at angular points of boundary & also in places where land is likely to be encroached upon INSCRIPTION:- The letters R,B indicating road boundary should be inscribed in each stone & below it name of authority in which road land vests i.e P.W.D,D.B etc 26. Cross section details of boundary stones as per IRC:25-1967 27. MATERIAL-locally available materials such as hard stone ,well dressed or of reinforced cement concrete LOCATION & FIXING:- They are to be located on the same side of road as one having kilometre stone .they may be fixed in position with rammed spails in mooram,lime surkhi concrete of lean cement concrete all around.they should be placed at edge of formation with their side bearing the inscription facing and parallel to centre line of road INSCRIPTION:-the inscription carried by the stones shall be the numerals 2,4,6 and 8 marked in an ascending order in direction of increasing kilometerage away from starting station.the numerals shall be 80 mm high. They should be properly painted or preferably engraved COLOUR:- the colour of shall be black on white background 28. SHAPES OF LETTERS/NUMERALS-All charecters having an arc at top or bottom are specified as per IRC:301968SPACING BETWEEN ADJACENT LETTERS/NUMERALS:The space between any combination of letters/numerals may be obtained by the two step process describe in footnote of table. this space is distance measured horizontally between extreme right edge of preceding letter and extreme left edge of following letter. no part of any letter/numeral may extend into this space. 29. The mountainous and steep terrains are collectively known as hilly terrainsTERRAINCROSS SLOPE`MOUNTAINOUS25%-60%STEEP>60%Hill roads are classified in five catagories.HILL ROADSNH SH MDR ODR VR 30. First step for alignment determination is fixation of obligatory points and control points which are determine by following factorsAdministrative needs Development needs Strategic needs To determine a few alternative alignment the investigation should start from obligatory summit points and proceed downwards Optimum alignment is the one which yeilds least overall transportation cost taking into account cost of construction and maintenance cost of road and have least adverse affect over environment Route should avoid introduction of hair-pin bends as far as possible 31. If provision of such bends are unavoidable then number of hair pin bends should kept at absolute minimum and inevitability of each bend should be recorded in reconnaissance report the bends should be located on flat and stable hill slopes and they should be avoided in valleys Series of hair pin bends on same face of hill should be avoided HAIR-PIN BENDS 32. 1)Reconnaissance 2)Preliminary survey 3)Determination of final centre line 4)Final location survey1)RECONNAISSANCE It is primary step of fixing the alignment, during this a general route for alignment is selected. A trace is cut thereafter corresponding to this an access is provided to subsequent surveys It can be conducted in following steps STUDY OF SURVEY SHEETS & MAPS:-in India topographical sheets are available to the scale of 1:50000,after study of the maps,a number of alignments feasible in a general way are selected.Topographical sheet 33. AERIAL RECONNAISANCE:- it provide a bird eye view and help to identify the factors which call for rejection or modification of any of alignment. GROUND RECONNAISANCE:- It consist of the general examination ground by walking or riding along the probable routes. it will be advantageous to start reconnaissance from highest obligatory point. FINAL RECONNAISANCE OF INACCISABLE AND DIFICULT STRETCHES:Above stretches may disclose certain stretches which call for detail examination. A trace cut is specially made in such section for inspection, it is also desirable to have one last round of aerial reconnaissance to resolve remaining doubts 34. 2)PRELIMINARY SURVEY:PEGGING AND TRACE CUT:- The line and grade of selected alternative is pegged and the trace is cut along the pegged route The gradient to be followed at this stage should be easier than those proposed to be achieved for the road by the margin of 10 to 20% The indication about the grade should be provided at conspicuous locations so that they can be easily visible from distanceTrace cut consist of 1.0 to 1.2 m wide track constructed along the selected alignment to facilitate access to the area for inspection and survey It is desirable that a senior engineer should walk over the trace cut before further survey work is undertaken to derive benefit from its experience for selection of best possible route 35. SURVEY PROCEDURE The survey should cover a strip width of 30m in straight/slightly curved and 60 m at sharp curve and hair pin bends Traverse along the trace should be run with a theodolite and all angles measured by double reversible method, distance should be measure with metallic tape and chain The transit station should be marked by means of stakes and numbered in sequence Leveling work include taking ground along the trace cut at intervals of 10 m and at abrupt changes in slope and also establishing bench marks at intervals of 250 m At sharp curves and difficult location detailed leveling may be done for plotting of contours. Interval of contours may be taken 2m though this could be varied as per site conditions 36. MAP PREPARATION:Plan should be prepared to determine final centre line of road . at critical section plan should show contour at interval of 1-3 m. scale of may be adopted as horizontal scale of 1:1000 and vertical scale of 1:100.scale can be increased at difficult location such as hair pin bendsDETERMINATION OF FINAL CENTRE LINE:Best alignment should be selected and study of horizontal alignment in conjunction with profile is carried out and proper adjustments should be made Horizontal curve including spiral transition should be designed and final central line should be marked over the mapVertical curve should be designed and profile shown in longitudinal section 37. 3)FINAL LOCATION SURVEY:TRANSIT SURVEY:i.All angles should be measured with a transit, reference marks should be fixed for this purposeii. These marks should be placed at 20 m at straight reaches and 10 m at curves iii. Reference pillars/Burjis should fixed on ground and should not be disturbed during construction . the maximum spacing between them should not be greater than 100m iv. Distance should be measured with help of theodolitev. Final centre line should be properly staked ,stakes being fixed at 20 m interval 38. BENCHMARKS:T o establish firm vertical control for location, design and construction benchmarks established during preliminary survey should be re checked and where likely to be disturbed during construction reestablished at interval of 250 m and or near all drainage crossing 39. The design speed of various categories of hill road are:-Normally ruling design speed should be the guiding criterion for correlating various geometric features. Minimum design speed may however be adopted in sections where site conditions including cost do not permit that 40. A hairpin turn (also hairpin bend, hairpin corner, etc.), named for its resemblance to a hairpin/bobby pin, is a bend in a road with a very acute inner angle, making it necessary for an oncoming vehicle to turn almost 180 to continue on the road. Hairpin turns are often built when a route climbs up or down a steep slope, so that it can travel mostly across the slope with only moderate steepness, and are often arrayed in a zigzag pattern. Highways with repeating hairpin turns allow easier, safer ascents and descents of mountainous terrain than a direct, steep climb and descent, at the price of greater distances of travel and usually lower speed limits, due to the sharpness of the turn. Highways of this style are also generally less costly to build and maintain than highways with tunnels. 41. Inner and outer edges of roadway should be concentric with respect to centre line of pavement Where hair pin bends have to be introduced a minimum intervening length of 60 m should be provided between successive bends to enable driver to negotiate the alignment smoothly At hair pin bends preferably the full roadway width should be surfaced 42. Passing places or lay-byes are require to cater following requirements 1)To facilitates crossing of vehicles from the opposite direction 2)To tow aside a disabled vehicle so that it does not obstruct traffic TYPE OF ROAD NH,SH having roadway width as per IRC:52-1981PROVISIONS FOR LAY-BYES NO NEEDSingle lane sections of NH/SH having narrow roadway widthMay be provided with respect to actual needsOther roadsProvided at rate of 2-3per kilometerLay-byes should be 3.75m wide,30m long on inner edge(towards the carriageway)and 20 m long on the farther side 43. Minimum lateral clearance(distance between the extreme edge of carriageway and the face of nearest support whether a solid abutment, pier or column) should equal to normal shoulder width. On lower category roads in hill areas having comparative narrow shoulders, it will desirable to increase width at underpass to a certain extent keeping in mind the principles of IRC:54-1974 44. Minimum vertical clearance of 5m should be ensured over the full width of the roadway at all underpasses and similarly at overhanging cliffs and any semi-tunnel sections etc The vertical clearance should be measured with regard to the highest point of carriageway(the crown or the super elevated edge of the carriageway) Allowance for any future raising/strengthening of pavement is also be made) 45. BRIDGE:-It is a structure having total length of above 6m between inner face of dirt wall for carrying traffic or other moving loads over the obstruction such as Channel, roads or railways It is of two types 1)MINOR BRIDGE:-total length up to 60 m 2)MAJOR BRIDGE:-Total length greater than 60 m CULVERT:-It is a cross drainage structure having a total length of 6 m or less HIGH LEVEL BRIDGE:-bridge which carries the roadway above high flood level SUBMERSIBLE BRIDGE /VENTED CAUSEWAY:-bridge designed to be overtopped during floods 46. LINEAR WATERWAY:- it is width of the waterway between the extreme edges of water surface at highest flood level measured at right angle to the abutment faces EFFECTIVE LINEAR WATERWAY:-it is the total width of waterway of the bridge at HFL minus the effective width of obstructions 47. SAFETY KERB:- it is a roadway kerb for occasional use of pedestrian trafficSAFETY KERB WIDTH OF CARRIAGEWAY:- it is minimum clear width measured at right angle to longitudinal centre line of the bridge between inside face of roadway kerbWIDTH OF THE SAFETY KERB:-It is minimum clear width any where within the height of 2.25 metres above the surface of the footway kerb 48. In case of road kerbs section shown below should be adopted. for bridges across deep gorges, major rivers, open sea the design below can be modified suitably They should be so designed that they would be safe for vertical and horizontal loads A safety kerb will have same outline as that of roadway kerb except top width shall not be less than 750mm 49. HIGH LEVEL BRIDGE FOR ROAD TRAFFICWIDTHSINGLE LANE4.25 MTWO LANE7.5 MFor every additional lane 3.5 m width should be increased, bridge should be provided only single lane or multiple of 2 laneIf median is provided than its width shall not be less than 1.2 m Minimum width of footpath should be 1.5 m 50. Apart from these following conditions must be satisfied by 2 lane bridge 51. Super elevation on the deck on horizontal curve should be provided as per relevant IRC standardsDue allowance should be made for the effect of superelevation on the stresses in various members of the bridge If there is a change of gradient on the bridge deck suitable vertical shall be introduced conforming the stipulations in IRC:SP-23 52. The approaches on either side of straight bridge shall have minimum length of 15 m and suitably increased where necessary to provide minimum sight distance If there is a change of gradient, suitable vertical curves shall be introduce as per IRC:23 A single vertical curve shall be provided for bridges having a total length of 30 m Approaches to vented causeway likely to be affected by flood shall be provided with suitable designed safety works 53. Suitably designed crash barriers should be provided as safeguard against errant vehicles They should be of metal or rcc and their design should consider following factors 1)impact of vehicle colliding the vehicle 2)safety of occupants of vehicle colliding the barrier 3)safety of other vehicle near the collision site 4)safety of vehicle and pedestrian underneath the bridge 5)aesthetics and freedom of view of passing vehicles They shall provide smooth and continuous face on traffic sideSuitable reflective devices shall be provided on the traffic face of barrier at intervals to ensure visibility 54. Types of crash barriers are:1)Vehicle crash barriers:-provided for bridges without footpaths 2)Combination railing/vehicle pedestrian crash barrier:-provide for bridges with footpaths3)High containment barriers:-provided mainly on bridges over busy railway lines complex interchanges and other similar high risk location. 55. High level bridges may preferably built in longitudinal gradient with suitably designed cross drains Suitable vertical recess in the piers may be provided to accommodate the drainage pipes rather than providing drip courses underneath deck slab All carriageway and footpath surfaces have anti skid characteristics 56. All multi lane shall be provided with overhead signs and signals as per IRC:67 Non luminous signs shall not be permitted Arrangement of supports for overhead structures are shown as below 57. Minimum horizontal & vertical clearance for single & multiple lane bridges with vehicular traffic are shown in figureUnless otherwise specified bridges shall have all their parts constructed to secure the minimum clearance for traffic given in figure 58. For footways and cycle tracks a minimum vertical clearance of 2.25 m shall be provided For a bridge constructed on a horizontal curve with super elevated road surface, the horizontal clearance shall be increased on side of inner curve by a amount of 5 m multiplied by super elevation 59. Lighting masts may be of the conventional type of suitable heights not less than 5.5mThe lamp may be chosen from the following 1. 2. 3. 4. 5. 6.incandescent lamp Mercury vapour lamp High pressure mercury lamp with clear fluorescent bulbs Tubular fluorescent bulb Sodium vapour lamp Mercury halide lamp The height & spacing should be such that to achieve minimum level of illumination of 30 lux Illumination level for the vehicular and pedestrian subways may be kept same as those on approaches at either end of subways.