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ENGIINEERING BRIDGE PART III

 
Fill in the Blanks.

1. TGI in Track Monitoring stands for Track Geometry Index.

2. The nominal size of aggregate that should be used for RCC is 20 mm.

3. The % of reservation applicable in case of promotions for SC employees is 15%.

4. The standard form used for generation of NS Indents for value upto Rs.10,000/- is 1302.

5. Returned Stores Vouchers are prepared in Form No. S.1539 in 6 copies.

6. Items of materials which have not been issued for a period of 24 months are classified as Surplus Stores.

7. Stagnation increments are admissible if an employee has been stagnating at the maximum of pay scale for not less than 2 years.

8. Rate of HRA allowed for A Class City is 15 %.

9. The duration of Paternity leave admissible is 15 days.

10. No. of School Passes for each student should be limited to 6 single journeys.

11. As per the V Pay Commission the maternity leave is increased from 90 days to 135.

12. If an employee is on a leave or sick continuously for more than 30 days, he is not eligible for Transportation Allowance.

13. The limit of commutation of pension has been raised from 33 1/3% to 40% in the V Pay Commission.

14. Two sets of Complimentary Passes are given to the Group-C employees whose total length of service is 25 and above.

15. Settlement Pass can be availed by the Retired Employee before 6 months of retirement.

16. The study leave that can be granted in the entire service to an employee is 24 months, except Group-D.

17. Equipment used for measurement of scour of river bed is Echo Sounder.

18. The edge distance for rivets is 1 d.

19. The maximum clear distance between bridge timbers is 450 mm and the minimum depth of sleeper is 150 mm for BG track.

20. The clearance between guard rail and running rail on bridges is 250 + 50.

21. Air pressure to be applied for cement pressure grouting is 2 to 4 kg / cm2.

22. Structural steel for fabrication of welded girders should conform to IS - 2062 and Grade B

23. A bridge with lineal water way of 300 m is classified as important bridge.

24. In Numerical Rating System, a condition which requires major / special repairs is indicated by the digit 3.

25. The minimum clearance between Rail Level and the bottom of FOB for electrified BG track is 6250.

26. No work shall be done within a distance of 2 m from the live parts of OHE without permit-to-work

27. Oiling & Greasing of bearing plates will be done once in 3 years at girder bridges.

28. On major bridges & long span bridges the trolley refuges are provided each pier.

29. A local weld used to assist assembly is called tag.

30. Rocker & Roller pinion bearings are normally used for Truss bridges.

31. A Jig is usually an appliance which guides Marking, Cutting & Drilling of holes in fabrication.

32. The rivets should not be over burnt as it would result in loss of metal.

33. Placing of new super structure over sub-structure is called regirdering

34. Bridge inspector is to be inspected welded girders once in 3 years.

35. Distressed bridges in Group II category are recommended for speed restriction of 25 to 50 kmph. While using RH girder, speed restriction 20 kmph should be imposed.

36. Category I classification of distressed bridge which requiring rehabilitation to be done immediately, say with in a years time.

37. The direction of flow should be distinctly marked in RAW tablet on an Abutment or pier.

38. Epoxy grouting is the remedial measure for longitudinal crack in the barrel along the inner face of the spandrel wall in arch bridge.

39. Diagonal cracks in arch come under Group I distress category.

40. The bridge inspector shall inspect early steel girder once in 3 months.

41. Shelf life of paint red oxide ready mixed (IS: 123) one year.

42. A 75x7x6mm M.S. square washer is used along with each hook bolt to prevent the nut from cutting into the sleeper.

43. The minimum grade of concrete for PSC girder is M35.

44. For epoxy grouting of bridges Epoxy Resin & Hardener shall be mixed.

45. SEJ is to be installed 30m away from the abutments.

46. The edge distance of a 20mm dia rivet shall not be less than 30mm.

47. If the crack is propagating in a direction perpendicular to stress in member of welded girders, 20 or 22mm dia holes may be drilled at crack ends to arrest propagation.

48. Elcometer is used for check the Dry Film Thickness of paint.

49. Sand blasting removes rust, millscale, old paint and creates a base for good adhesion.

50. Rivet Testing Hammer is used for testing loose rivets in field.

51. Rivet testing hammer weight shall be 110gms.

52. Steel triangulated girders are provided with camber to compensate for deflection under load.

53. Dye penetration test is to detect cracks during inspection of welded girders.

54. Tell-tales shall be fixed when cracks are detected in bridge to verify further propagation.

55. Site welding can be done for connections having low stress, secondary members and bracing of girders.

56. Bridge Inspector shall carry out the initial inspection of welded girders in detail within one year after installation.

57. CRN 2 is allotted at the time of inspection of a bridge for a condition which requires rebuilding / rehabilitation on a programmed basis.

58. Calender Hamilton spans are temporary girders and generally used during breaches.

59. For epoxy grouting of bridges epoxy resin and hardener shall be mixed.

60. Speed Restriction of 15 KMPH is suggested for distressed bridges on Group I.

61. Periodicity of inspection by BRI concerned for Category I distressed bridge is 1 month and for category II is 3 months.

62. Safety refuges: Max. distance apart of refuges in tunnels 100m

63. Min. height above rail level for a distance of 1600mm on either side of center of track where 25KV Ac traction in use light overhead structure such as FOB shall be 6250mm

64. Depth of bridge sleepers should not be less than 150mm and spacing shall not exceed 450mm+width of sleeper.

65. Height gauges to be erected at entry of Road Under Bridge.

66. Each dip lorry set can carry material of weight upto 15000Kgs.

67. Phospher Bronze bearing is corrosion resistant, having smooth surface and hence greasing not required.

68. Floor system of through type Girder Bridge consists of cross girders, stringers.

69. Min. length of steel channel sleepers on girder bridges is out side to out side of flange +305mm not less than 2440mm.

70. Asst. Bridge Engineer is required to make 10 % test check of the bridges inspected by Bridge Inspector every year.

71. Bridge Inspector will be responsible for painting, Riveting and other repairs to steel work of all girder bridge irrespective of span.

72. Bridge Inspector shall refer any work likely to affect track or moving dimensions to the ABE/ADEN for instructions.

73. The HFL line should be painted distinctly in a 25mm broad white line along with the year of its occurrence in figures 100mm deep.

74. A bridge foundation having less than 2m depth below bed level in case of arch bridges, 1.2m below bed level for others is termed as shallow foundation.

75. A foundation, which is deep enough, having required grip length below max. Scour level is termed as deep foundation.

76. Boundary pillar on each bank of a river or important waterway shall be erected so as to prevent and control encroachment.

77. Steel triangulated girders are provided with camber to compensate deflection under load.

78. In case of cracks in arch bridges, pressure grouting with cement mortar at a pressure 2 to 4 kg/sqcm.is generally quite effective.

79. The danger level shall be fixed at each bridge by the DEN/Sr.DEN with great caution and due regard to the site condition.

80. On selected bridges where high winds are experienced and there is a danger of vehicle capsizing, Anemometer should be installed at one of the railway station close to the bridge.

81. A spur is a structure constructed transverse to the river flow and is projected from the bank into the river.

82. Each vulnerable cutting should be inspected before onset of rains as in the case of bridges and tunnels by the AEN concerned.

83. To prevent erosion, stone pitching may be provided on the approach banks, marginal bunds, and at closure bunds.

84. Weathering damage will be indicated by layers of material spalling off.

85. To avoid build up of hydrostatic pressure Weep holes should be provided at 1m intervals in both horizontal and vertical directions.

86. Vertical cracks in the substructure may occur due to differential settlement of the foundation.

87. Transverse cracks in arch barrel (intrados) are serious in nature and indicate presence of tensile stresses at the intrados.

88. Coarse aggregate used in shotcrete should conform to IS: 383, with a maximum nominal size of 10 to 12.5 mm.

89. The grease gun syringe should be washed with acetone immediately after epoxy grouting.

90. Loss of camber can be mainly attributed to overstressing of members beyond the elastic limit.

91. The length of the rivet shank may be worked out by the formula L = G + 1.5D + 1mm for every 4mm of grip or part there of for snap head rivet.

92. While riveting a loose joint, not more than 10 % rivets should be cut at a time.

93. At locations where replacing rivets is difficult, turned bolts of appropriate diameter and length may be used.

94. Metallising - a form of protection by spraying a metal either zinc or Aluminium.

95. Flame cleaning should not be done on plates with thickness 10mm or less.

96. The shelf life of paint aluminium used in the Railways when paste and oil are not mixed is1year.

97. The shelf life of Oil linseed boiled is 2 years.

98. The shelf life of Red lead dry pigment is No time limit.

99. The maximum time lag between surface preparation and the application of primer coat - 24 hours.

100. The maximum time lag between application of primer coat and the 1st finishing coat 7 days.

101. The maximum time lag between 1st finishing coat and the 2nd finishing coat - 7 days.

102. In metallising the minimum thickness of metal coating applied shall be 115 microns and average thickness 150 microns.

103. After the metallising the first coat shall be wash primer to SSPCPT - 3 53T or Etch primer to IS : 5666.

104. If bed block is shaken it should be inspected under traffic for visible movements.

105. For stone masonry, the proportion of cement mortar used should be minimum 1: 4.

106. When mass cement concrete is used the mix shall be minimum M.20.

107. Masonry piers are provided with a better varying from 1 in 24 to 1 in 12.

108. In order to reduce impact effect and to obtain improved running, properly designed approach slabs may be provided on both the approaches of non-ballasted deck bridges having spans of 12.2 m or more.

109.Length of the approach slab shall be minimum 4 m.

110. The boulder filling should not be less than 600 mm thickness behind the abutment and wing walls.

111.For concrete richer than M-20 proportioning shall be done by weigh batching only.

112. All works in PSC shall be done with weigh batching only.

113. Portland pozzolana cement shall not be used for PSC and RCC works.

114. Where a skew crossing is unavoidable in construction of a bridge it is advisable to restrict the skew to 30.

115. The river should be surveyed for a distance of 8 kms. upstream and 2 kms. downstream of the location of the bridge and measured at right angles to the center line of the Railway.

116. The average slope of the river bed is to be determined from a point about 2 kms. upstream of the Railway crossing to a point 2 kms. downstream of the same.

117. For estimation of design discharge for waterway, the probable recurrence intervals of computed flood is 50 years.

118. The minimum vertical clearance for bridges excluding arch bridges, syphons, pipe culverts and box culverts from the water level of design discharge 301 to 3000 cumecs including afflux, shall be 1500mm.

119. The minimum vertical clearance for bridges excluding arch bridges, syphons, pipe culverts and box culverts from the water level of design discharge above 3000 cumecs including afflux, shall be 1800mm.

120. In the case of arch bridges, minimum vertical clearance measured to the crown of the arch span less than 4m shall be Rise or 1200 mm. whichever is more.

121. In the case of arch bridges, minimum vertical clearance measured to the crown of the arch span 4m to 7m shall be 2/3 Rise or 1500 mm. whichever is more.

122. In the case of arch bridges, minimum vertical clearance measured to the crown of the arch span 7.1m to 20m shall be 2/3 Rise or 1800 mm. whichever is more.

123. In the case of arch bridges, minimum vertical clearance measured to the crown of the arch span above 20m shall be 2/3 Rise.

124. The free board from the water level of the design discharge to the formation level of the Rly embankment or the top of guide bund including afflux shall not be less than 1m.

125. Where adoption of the prescribed values for Free board would result in heavy expenditure; it may be relaxed as 600mm for discharge less than 3 Cumecs.

126. Where adoption of the prescribed values for Free board would result in heavy expenditure; it may be relaxed as 750mm for discharge 3 to 30Cumecs.

127. Open foundation is suitable for bridges where rock or firm subsoil is available at shallow depth.

128. Pile foundation can be quiet economical, particularly where the foundations have to be built very deep.

129. Well foundation is most suited for riverbeds subjected to heavy scour.

130. In rocky soil, the foundation will be adequate if it is properly keyed into the rock for a minimum of 0.3 metre in case of hard rock and 1.5 metres in case of soft rock.

131. When excavations have to be deep or when the side slopes are not stable, shoring may be provided from top, using timber planks etc.

132. Where excavation is required to be done under flowing or standing water, coffer dams of steel sheet pile, RCC or timber may be constructed.

133. Friction piles are used in soils not subjected to scour.

134. Bearing piles transfer the load primarily by bearing resistance developed at the pile tip or base, generally used in hard stratum.

135. Large diameter bored piles of more than one metre diameter are normally used for Railway bridge construction.

136. The length of driven piles normally does not exceed 25 to 30 m depending on the capacity of the driving equipment.

137. Where piles derive their capacity mainly from end bearing, the minimum spacing cases shall be 2.5 times the diameter of the pile shaft.

138. Where piles derive their bearing capacity mainly from friction, the spacing shall not be less than 3 times the diameter of the pile shaft.

139. Normally centre to centre spacing should not be more than 4 d, where d is the diameter of pile shaft.

140. Distressed bridge Category-I requires rehabilitation to be done immediately, say within a years time.

141. Distressed bridges Category-I requires rehabilitation to be done on a programmed basis

142. For distressed bridges on Group I suggested speed restrictions is 15 kmph

143. For distressed bridges on Group II suggested speed restrictions is 25to50 kmph.

144. Distressed bridge having sign of Settlement of foundations comes under Group 1.

145. Distressed bridge having sign of Progressive loss in camber comes under Group 1.

146. Distressed bridge having sign of Transverse cracks in arches comes under Group 1.

147. Distressed bridge having sign of Shaken/ displaced/ cracked bed blocks comes under Group 1

148. Distressed bridge having sign of Cracks/ heavy corrosion in load bearing members of steel girders comes under Group 1.

149. Distressed bridge having sign of Bulging or separation of spandrel from arch barrel of foundations comes under Group II

150. Distressed bridge having sign of Cracks in return walls/ wing walls of

foundations comes under Group II.

151. Inspection of distressed bridges category I shall be carried out by inspector

concerned once in a month.

152. Inspection of distressed bridges category II shall be carried out by inspector

concerned once in 3 months.

153. Inspection of distressed bridges category I shall be carried out by ADEN/ABE once in 2 months.

154. Inspection of distressed bridges category II shall be carried out by ADEN/ABE once in 6 months

155. Inspection of distressed bridges category I shall be carried out by DEN/Sr.DEN once in 3 months

156. Inspection of distressed bridges category II shall be carried out by DEN/Sr.DEN once in a year.

157. When the headroom is restricted for making bored piles, well foundations can be constructed.

158. Whenever settlement is noticed in piers and abutments the rail level should be maintained by making up with packing plates or steel stools.

159. For strengthening substructure jacketing with cement concrete is to be done with minimum thickness of 150 mm.

160. In jacketing the dowels may be of 20 mm diameter deformed rods provided in a staggered manner at 450 mm centres in both horizontal and vertical direction.

161.Holes for dowels should be drilled and not made by pavement breakers.

162.Individual bed blocks, which are cracked, can be replaced with through RCC bed blocks.

163. In general the length of plate girder is restricted to about 12m so as to facilitate transport in single lengths..
164.Bridge Inspector will be responsible for painting, riveting, welding and their repairs to the steel work of all girder bridges including clear span less than 12.2m.

165. All welded, RCC, PSC and composite girders and their bearing within one year of installation.

166. ADEN shall inspect every tunnel in the sub division once a year before monsoon.

167. The Bridge Inspector shall refer any work likely to affect track or moving dimensions to the ABE and ADEN for instructions.

168. The Permanent Way Inspector shall be responsible for the posting of bridge watchman, wherever necessary and ensure their effective functioning.

169. Elastomeric bearings are made of natural or synthetic rubber of shore hardness f approximately 50 to 70.
170. The roller and rockers are scraped, polished with zero grade sand paper and greased with grease graphite.

171. The HFL line should be painted distinctly by a 25mm broad white line along with the year of its occurrence, in figures 100mm deep.

172. HFL line should be painted on the downstream side.

173. Name boards at important bridges should be fixed at either approach at a distance of about 15 metres from the abutment.

174. Whenever heavy scour is noticed on the downstream of the drop walls, scour
hole should be filled with boulders or wire crate.

175. For masonry abutments, a front batter of 1 in 16 to 1 in 10 is used.

176. Whenever MG bridges are rebuilt the substructure and superstructure shall be built to BG standards.

177. Black cotton soil should in no case be used for filling purpose.

178. Whenever a crack is detected in the steel work, as a first remedial step, a small hole of 7mm diameter should be drilled at the extremities of the crack to prevent its further propagation.

179. The cracked member in steel work may be strengthened by cover plate adequately riveted.

180. In riveting process adequate air pressure of 5.6 to 7 kg/cm2 should be ensured for opening of the tools.

181. While painting with red oxide paint, a little quantity of lamp black shall be added to the paint while doing the first coat to distinguish it from the second coat.

182.While painting with aluminium paint, a little quantity of blue paint shall be added to the paint while doing the first coat to distinguish it from the second coat.

183. Girders, which are overstressed and kept under observation, should be inspected at least once in a year by Bridge Inspector.

184. All early steel girders should be inspected once in 3 months by Bridge Inspector.

185. The steel work and bearings of all girder bridges including those less than 12.2m span and Road Over / Under Bridges once in five years by Bridge Inspector.

186. While jacketing, dowels should be taken down to a depth of not less than 200mm inside the masonry/concrete.

187. The spacing of dowel rods should not be more than 450mm horizontally and vertically.

188. Jacketing below bed level should be done under speed restrictions 15 km/h to 30 km/h depending on the extent of exposure, type of soil etc.

189. Oil bath bearings are generally provided for new girders of spans above 76.2m where it is difficult to lift the girders for periodic greasing.

190. In the case of roller bearings with oil bath, replenishing the oil should be done annually.

191. Wherever oil bath bearings are provided, inspection of the bearings should be carried out at least once in 5 years.

192. Lubricating the mating surface by silicon grease reduces the coefficient of friction for PTFE bearings.

193. The well steining should be built up in stages initially 1.20 to 1.50 metres at a time.

194. Sinking of steining should not be done within 48 hours of casting.

195. The danger level is that level which when reached, safety of the bridge is likely to be adversely affected.

196. Danger level can be marked for box culvert at the bottom of slab.

197. Danger level can be marked for pipe culvert at the top of inside of pipe.

198. The danger level should be marked on the bridge on up stream side..

199. The danger level should be marked with a bright red band 5 cm wide centrally over a white band 10 cm wide for a length of 60 cms.

200. Soundings at bridges can be taken when flood is at or about the danger level with echo sounder.

201. Afflux gauges should be fixed at a distance of about 30 metre upstream and downstream of the bridge opening.

202. When there is very heavy rainfall, hourly readings should be taken to assess the intensity of rainfall.

203. Where high winds are experienced and there is a danger of vehicle capsizing, anemometers should be installed at one of the railway station close to the bridge.

204.On bridge locations the dangerous wind velocity specified by the Chief Engineer is 65 Kmph.

205. Amount of rainfall to be considered as dangerous is 5 cm and above in 24 hours.

206. Guide bunds are meant to confine and guide the river flow through the structure without causing damage to it and its approaches.

207. A spur is a structure constructed transverse to the river flow and is projected form the bank into the river.

208. The Permanent way Inspector shall inspect every tunnel on his section once a year during the prescribed month after the monsoon season.

209. The Assistant Engineer shall inspect every tunnel on the sub division once a year before the monsoon during the prescribed months.

210. Each vulnerable cutting should be inspected before the onset of rains by the AEN.

211. Stationary watchmen should be posted round the clock at nominated vulnerable cuttings during the monsoon period.

212. Sufficient sheets may be allotted for each bridge so that at least ten years records can be contained in one register.

213. If in any bridge, one or more components do not exist, the CRN for such components shall be shown as 6.

214. In URN 4th digit denotes condition of training and protective works of a bridge.

215. In URN 8th digit denotes condition of track structure of a bridge.

216. In URN 2nd digit denotes condition of foundations and flooring of a bridge.

217. In URN 6th digit denotes condition of bearings and expansion arrangements of a bridge.

218. In URN 7th digit denotes condition of superstructure of a bridge.

219. In URN 5th digit denotes condition of bed blocks of a bridge.

220. n URN 3rd digit denotes condition of substructure of a bridge.

221. In URN 1st digit denotes overall rating number of a bridge condition.

222. Position of arrows on top of the hook bolts should be at right angles to the rails

pointing towards the rail.

223. Rail joints should be avoided within three metres of a bridge abutment.

224. ull sections of ballast should be maintained for at least 50 metres on the approaches.

225. Long unballasted girder bridges located between stations are to be provided with footpaths for the convenience of engineering staff.

226.The flood gauges have to be provided at important bridges for recording flood levels and afflux.

227. The camber of prestressed concrete girder should be checked once a year.

228. The common methods of strengthening of weak girder is replacement of weak rivets by larger diameter rivets.

229. Inspection of bridges on Cast Iron Screw pile foundation and early steel girders should be done by SE/SSE(Br) once in 3 months.

230. Inspection of bridges on Cast Iron Screw pile foundation and early steel girders should be done by ABE) once in 6 months.

231. Inspection of bridges on Cast Iorn Screw pile foundation and early steel girders should be done by DEN/Br once in a year.

232. Dry Film Thickness of paint Red lead IS: 102-1962 is 80 microns.

233. Dry Film Thickness of paint Red oxide IS: 123-1962 is 45 microns.

234. Dry Film Thickness of paint Aluminium IS: 2339-1962 is 35 microns.

235. Painting of steel girder bridge should be avoided during rainy season.

236. Paint should be mixed in small quantities sufficient to be consumed within 1 hour in the case of red lead paint.

237. Paint should be mixed in small quantities sufficient to be consumed within 5 days in the case of red oxide paint.

238. Standard plate girders are provided with no camber, and open web girders of span 30.5m and above are provided with camber. True/False.

239. For spans more than 6.1m, rail joints should preferably be provided at 1/3rd.of  span from either end.

240. The clear distance between bridge timbers at joints should not exceed 200.mm both B.G and M.G.

241. Bridge sleepers are numbered serially on every sleeper span wise. True/False

242. Guard rails should be provided on all girder bridges whether major or minor. True/False.

243. Length of bridge timbers should be distance of outside to outside of girder flanges plus 305 mm but not less than 440 mm for B.G.

244. Maximum centre to centre spacing of steel channel sleepers for B.G. is 680 mm.

245. The Railway affecting tank, which still requires heavy repairs, despite repeated reminders of Railway, should be considered and included in the list of vulnerable locations. TRUE/FALSE

246. Under-water substructure inspection in costal areas should be carried out once in 3 years.

247. Under-water substructure inspection in non-costal areas should be carried out once in 5 years.

248. Under-water substructure inspection of bridges more than 100 years old should be carried out once in 3 years.

249. Paint should be mixed in small quantities sufficient to be consumed within1 hour in the case of red lead paint.

250. Paint should be mixed in small quantities sufficient to be consumed within 5 days in the case of red oxide paint.

251. The drying time shall not be less than 3 days in the case of Red lead paint.

252. Mixing of kerosene oil with paint is strictly prohibited.

253. In shotcreting, Sand when used, should conform to IS : 383 and graded evenly from fine to coarse as per Zone II and III with a nominal max. size of 6mm.

254. In shotcreting, Coarse aggregate, when used, should conform to IS: 383, with a maximum nominal size of 10 to 12.5 mm.

255. Normally the upstream shank of the guide bund is about 1.0 to 1.5. times the length of the bridge

256. The upstream shank of the guide bund is about 1.0 to 1.5. times the length of the bridge.

257. Ordinary Portland cement conforming to IS 269 shall be used for plain,reinforced and prestressed concrete work.

258. Ferrous metal is recommended for duct material.

259. Provision shall be made to cater for an additional prestressing forces of 15% of the design prestressing force, for easy installation of prestressing steel at a later date.

260. The trestles may consist of starred angles forming a square section.

261. Size of c.c crib is 600 x600 x1800mm.