PUP Civil Engineering Department Highway and Railroad Engineering PDF

PUP Civil Engineering Department #WeLearnAsOne The construction of a new railway line is a capital-intensive project and each kilometer of a new railway line costs depending upon the topography of the...

PUP Civil Engineering Department #WeLearnAsOne The construction of a new railway line is a capital-intensive project and each kilometer of a new railway line costs depending upon the topography of the area, the standard of construction, and such other features. It is, therefore, natural that a lot of thought be given when making a final decision as to whether a new railway line is at all necessary or not. ▪ Strategic Reasons ▪ Political Reason ▪ Development of Backward areas ▪ To connect new Trade Center ▪ To Shorten the existing rail Tack Preliminary Investigations for a New Railway Line The railway administration determines how the proposed line will fit in with the general scheme of future railway development. The preliminary investigations are normally based on a careful study of the following: Existing topo sheets and other maps of the area Published figures of trade and population of the area to be served Statistical data of existing railway lines in similar terrain in other areas Module 3 | Pavement Learning Objectives Upon successful completion of this course, the student should be able to: Understand the two major types of pavement present in the Philippines; Understand the different concrete and asphalt pavement activities; Learn basic understanding of the required design data, design criteria and standards, and design procedures of Portland Cement Concrete Pavement (PCCP), Asphalt Concrete Pavement (ACP), and AC overlay over PCCP. Course Material 4. PAVEMENT 4.1. Types of Pavement - Road pavement is of two major types - rigid pavement (PCCP) and flexible pavement (ACP). Load Distribution for Rigid and Flexible Pavement 46  PUP Civil Engineering Department #WeLearnAsOne 4.1.2. Rigid Pavement - A rigid pavement generally consists of three layers: the concrete slab, subbase and subgrade as described below: Slab - The slab is made of reinforced or plain concrete which also includes load transfer devices and joint sealing materials. The concrete slab acts like a bridge girder over the subgrade. Subbase - The slab is made of reinforced or plain concrete which also includes load transfer devices and joint sealing materials. The concrete slab acts like a bridge girder over the subgrade. Subgrade - It is the bottom portion of the pavement structure which consists of suitable embankment materials or existing road bed. 4.1.3. Flexible Pavement - A flexible pavement generally consists of four layers: surface course, base course, subbase and subgrade (which is the prepared roadbed) as described below: Surface Course - It consists of a mixture of mineral aggregates and bituminous materials constructed on a prepared base course. Base Course - It is the portion of a pavement structure immediately beneath the surface course. It consists of aggregates such as crushed stone, crushed slug, crushed or uncrushed gravel and sand or a combination of these materials placed and compacted on a prepared subbase. Subbase It is the portion of the pavement structure between the subgrade and the base course. It consists of a compacted layer of granular materials placed on a prepared subgrade. Subgrade - It is the bottom portion of the pavement structure which consists of suitable embankment materials or existing road bed. 4.2. Quality Control for PCCP - The Contractor shall perform all sampling, testing and inspection necessary to assure quality control of the component materials of the concrete. The Contractor shall be responsible for determining the gradation of fine and coarse aggregates and for testing the concrete mixture for slump, air content and temperature. He shall conduct his operations so as to produce a mix conforming to the approved mix design. 4.3. Design Mix and Trial Paving - The Contractor is obliged to formulate the design mix, conduct trial mix and trial paving for approval of the Project Engineer before commencement of pavement construction as illustrated in figure below. Flow Chart of Preparatory Work for Conceptual Paving 4.4. Admixtures or Additives - Admixture/additive shall be added only to the concrete mix to produce some desired modifications to the properties of concrete whenever necessary, but not as partial replacement of cement. The admixtures shall conform to the requirements as tabulated below: 47  PUP Civil Engineering Department #WeLearnAsOne Requirements for Admixtures 4.5. Concrete Paving for Activities - The following photos show concrete pouring activities: 4.6. Types of Form Works - There are two types of formworks for concrete paving - fixed-form and slip form. The use of slipform paver is required in DPWH road projects as per D.O. 219 Series of 2000. 4.7. Weakened Plane Joint All joints shall be protected from the intrusion of injurious foreign material until sealed. All joints shall be cut within 4 to 24 hours after pouring and thereafter sealed with asphalt sealant. The depth of the weakened plane joint shall not be less than 50 mm while the width not more than 6 mm. Only concrete saw is permitted in the cutting of weakened plane joints. According to international practice, dowel bars are required in all contraction joints (at 4.5m) as load transfer 48  PUP Civil Engineering Department #WeLearnAsOne device for PCCP with thickness of more than 200 mm. The PCCP slabs without dowel bars at weakened joint will cause various defects in the medium to long term, especially for the road route on which heavy trucks are dominant. The types and functions of PCCP joints are summarized below: 4.8. Rigid Pavement (PCCP) Rigid Pavements generally consists of prepared roadbed underlying a layer of subbase and pavement slab. AASHTO formula used in the analysis of Rigid Pavement: 𝑙𝑜𝑔 [ ∆𝑃𝑆𝐼 ] 10 4.5 − 1.5 𝑙𝑜𝑔 𝑊 = 𝑍 × 𝑆 + 7.35 × 𝑙𝑜𝑔 (𝐷 + 1) − 0.06 + 10 18 𝑅 𝑂 10 1.624 × 107 1+ (𝐷 + 1)8.46 ‫ﻟ‬ 1 I I 𝑆′ × 𝐶 [𝐷0.75 − 1.132] + (4.22 − 0.32𝑝 ) × 𝑙𝑜𝑔 𝑐 𝑑 (𝑒𝑞𝑢𝑎𝑡𝑖𝑜𝑛 1 − 1) 𝑡 10 ❪ 18.42 ❵ 215.63 × 𝐽 [𝐷0.75 − ] I 𝐸𝐶 0.25 I 𝗅 (𝑘) 𝖩 Where: 𝑊18 = predicted number of 18-kips equivalent single axle load (ESAL) application 𝑍𝑅 = Standard normal deviate 𝑆𝑂 = Combined standard error of the traffic prediction and performance prediction 𝐷 = Thickness (inches) of pavement slab ∆𝑃𝑆𝐼 = Difference between the initial serviceability index (Po) and the design terminal service ability (Pt) 49  PUP Civil Engineering Department #WeLearnAsOne 𝑆𝑐′ = Modulus of rupture (psi) for Portland Cement Concrete Sc + Z(Sds) 𝐽 = Load transfer coefficient used to adjust for load transfer characteristics of a specific design 𝐶𝑑 = Drainage coefficient 𝐸𝐶 = Elastic Modulus of PCC 𝑘 = Composite Modulus of subgrade reaction Step 1: Cumulative Equivalent Single Axle load (CESAL), W18 (refer to DO 22 series of 2011) Design Traffic Design Traffic for each vehicle type can be solved using the formula below: (1 + 𝑔)𝑛 − 1 𝐷𝑒𝑠𝑖𝑔𝑛 𝑇𝑟𝑎𝑓𝑓𝑖𝑐𝑖 = 𝑃𝑖 [ ] × 365 𝑔 Where:𝑃𝑖=Annual Average Daily Traffic 𝑔= Traffic Growth Rate 𝑛= Design Perio Equivalence Factor, EF Equivalence Factor (EF) for each vehicle type can be solved using the formula below: 𝑎𝑥𝑙𝑒 𝑙𝑜𝑎𝑑 (𝑡𝑜𝑛𝑠) 4 𝐸𝐹𝑖 = ∑ [ ] 8.2 Distribution Factors a. Directional distribution Factor – Generally 50% for two (2) way roads b. Lane distribution Factor – Please Refer to Table 1 for the range of value based on the number of lanes per direction. Compute the Cumulative Equivalent Single Axle Load (CESAL) for each vehicle type. 𝐶𝐸𝑆𝐴𝐿𝑖 = 𝐷𝑒𝑠𝑖𝑔𝑛 𝑇𝑟𝑎𝑓𝑓𝑖𝑐𝑖 × 𝐸𝐹𝑖 Add the CESAL for all vehicle types multiplied by the distribution factors. 𝐶𝐸𝑆𝐴𝐿 = ∑ 𝐶𝐸𝑆𝐴𝐿𝑖 × 𝐷𝐷 × 𝐷𝐿 Step 2: Level of Reliability, R Standard Normal Deviate (ZR) A variable in the AASHTO Formula that is dependent on the Reliability Factor (R). The normally used reliability factor for national roads in the Philippines is 85%. Suggested Levels of Reliability for Various Function Classification Functional Classification Recommended Level of Reliability Urban Rural Interstate & other freeway 85-99.9 80-99.9 Principal Arterial 80-99 75-95 Collectors 80-95 75-95 50  PUP Civil Engineering Department #WeLearnAsOne Based on Reliability Reliability R Standard Normal Deviate ZR 50 0 60 -0.253 70 -0.524 75 -0.674 80 -0.841 85 -1.037 90 -1.282 91 -1.340 92 -1.405 93 -1.476 94 -1.555 95 -1.645 96 -1.751 97 -1.881 98 -2.054 99 -2.327 99.9 -3.090 99.9 -3.750 Step 3: Combined Standard Error of the Traffic Prediction and Performance Prediction (So) The Overall Standard Deviation (SO) is one of the criteria required for the consideration of reliability. Although it is possible to estimate this parameter through analysis of variance of all design factors, an approximate value must be considered. Values of between 0.30 - 0.40 have been used for SO for rigid and values of between 0.40 - 0.50 for flexible pavement as mentioned in the AASHTO Guide.. Step 4: Design Serviceability Loss, ∆𝑷𝑺𝑰 Initial Serviceability Index, Pi Pi is equal 4.5 for Rigid Pavement Terminal Serviceability Index, Pt Pt is equal to 2.5 or higher for major highways and 2.0 for lesser traffic volumes Use the equation below to solve for Design Serviceability Loss, ∆𝑷𝑺𝑰 ∆ 𝑃𝑆𝐼 = 𝑃1 − 𝑃2 Where: P1 : PSI immediately after overlay P2 : PSI at time of next rehabilitation Step 5: Modulus of Rupture (S’c) As per DPWH specification S’c= 550 psi for 14 days. As per AASHTO 1993, if construction specification will be used, then necessary adjustments should follow using the formula below: 𝑆′(𝑚𝑒𝑎𝑛) = 𝑆 + 𝑧(𝑆𝐷 ) 𝑐 𝑐 𝑠 51  PUP Civil Engineering Department #WeLearnAsOne Where: 𝑆𝑐′ = estimated mean value for PCC modulus of rupture 𝑆𝑐 = construction specification on concrete modulus of rupture (psi) 𝑆𝐷𝑠 = estimated standard deviation of concrete modulus of rupture (psi) 𝑆𝐷𝑠 = 𝑃𝑆(𝑆𝑐), PS value refer to Table 5 𝑧 = standard normal deviate Usual value used for design: 𝑆𝑐 = 550 psi for 14 days 𝑆𝐷𝑠 = 𝑃𝑆(𝑆𝑐) = 0.15 × 550 𝑧 = 1.037 𝑆𝑐(𝑚𝑒𝑎𝑛) = 550 + 1.037(0.15 × 550) ′ 𝑆𝑐′(𝑚𝑒𝑎𝑛) = 635.55 𝑝𝑠𝑖 Step 6: Load Transfer Coefficient, J Measure joint load transfer in the outer wheel path at a representative transverse joints. Do not measure load transfer when the ambient temperature is greater than 80°F. Place the load plate on one side of the joint with the edge of the plate touching the joint. Measure the deflection at the center of the load plate and at 12 inches from the center. Compute the deflection load transfer from the following equation. Load Transfer Co-efficient Percent Load Transfer “J” >70 Load 3.2 50- 70 Transfer 3.5