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Design of proposed highway
The document outlines the geometric design of a proposed highway project, detailing the evaluation of two alternative routes based on specified criteria such as environmental impact and cost. After analysis, route B was selected for its technical feasibility, while route A was deemed unsuitable due to excessive uphill hauling and other concerns. The report further includes specifications on horizontal and vertical alignments and associated computations necessary for the design process.
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Design of proposed highway
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- 2. TABLE OF CONTENTS LOCATION MAP BACKGROUND AND SPECIFICATIONS ALTERNATIVE ROUTES SCREENING OF ALTERNATIVE ROUTES HORIZONTAL ALIGNMENT HORIZONTAL CURVE COMPUTATIONS PROFILE (VERTICAL ALIGNMENT) VERTICAL CURVE COMPUTATIONS CROSS SECTIONS
- 3. LOCATION MAP The location map indicates the topographic features in the area of the route and selected end points where connections with the existing roads are to be made. Obviously, the route cannot be indicated until the preliminary design has been completed. In addition, it is usually important that the location map be properly identified with regard to state, country, municipal, and other jurisdictional boundaries, (including federal) agencies and other interests. In practice, it would also be usual to relate the proposed highway to the regional highway network.
- 4. 8 1 9 90 0 1000 950 900 850 8 5 2 E A B 1 1 0 1 1 9 4 0 850 E n d p o in t E B E G IN N I N G P O IN T 810 810 B 19 9 5 1 0 0 0 850 840 9 7 0 830 840ABONDONEDROAD 800 800 790 790 780 780 Specified end points of proposed highway Beginning point – B End point ‐ 1 DRAWING NO: Figure Title: LOCATION OF PROPOSED HIGHWAY SCALE (S) : As shown
- 5. BACKGROUND AND SPECIFICATIONS This section provides the basic information which the designer relies upon to select the routes and undertake the design. The information should be clearly stated also because it informs others about the base guidelines and assumptions that have affected the outcome. These guidelines and assumptions may be the subject of future policy changes resulting from the review of the preliminary design but typically do not change during the preliminary design process. In this project the background and specifications are presented in the following pages: Introduction and Background: The preliminary route selection and design of the proposed highway is intended to exist in exploring the cost and land use implications of connecting North road with Southwest Road at points B and 1 respectively, shown on the location map. Tentative analysis of future traffic levels has been made, including consideration of potential use of the state reservation as an environmental research area, with possible public access. Objectives: In accordance with above background, it is required to conduct a preliminary route selection and design for a 2 lane highway in accordance with AASHTO “Rural collector” highway design standards. Two alternative routes initially investigated. However, only one Route is to be selected for the design process, immediately following a brief screening of both routes. Design policy: In addition to Using the AASHTO policy on geometric design for “rural collector” highway as basic design guidelines, several more specific guidelines has been defined within the IDOT and general policy, resulting from examination or the environs of highway and its likely uses. The traffic control devices should be provided in accordance with the latest version of MUTCD and local regulations.
- 6. Design designation: Classification =Rural Collector Design speed =40mph ADT (current year) =0 ADT (future year) =4000 K =10% D =60% T =2% Design Controls: Design speed, V =40mph Super elevation rate, e(max) =6% Minimum Radius for above V and E =485 ft (Also satisfies stopping sight dist. Requirements for horizontal curves) Maximum grade, except at intersections =6% Minimum grade (All locations) =0.5% Maximum Vertical curve K value, drainage criteria =167 Design vehicle =WB‐50 Intersection Geometrics: Horizontal intersection of proposed route with existing highway should be a minimum of 100ft tangent segment as close to 90°as possible to the existing highway, but within the range of 75° to 105°. Maximum grade (+ or ‐) within 100ft of intersection Lane Requirements: Two lanes are minimum number of lanes for an adequate design. Therefore, the highway will comprise 2‐12ft lanes with 8ft shoulders.
- 7. ALTERNATIVE ROUTE From the examination of the contours and terrain, two possible routes, A and B, were defined, as shown in the figure. In the plan view of these routes, the curves have been shown to conform with the minimum required radius. In the profiles shown in figure, both alternatives comply with the required controls, and Route A is approximately 403ft longer than B. (fig) 819 900 1000 950 900 850 852 E A B 1 1011 940 850 End point E B EG IN N IN G PO IN T 810 810 B 1995 1000 850 840 970 830 840ABONDONEDROAD 800 800 790 790 780 780 ROUTE B ROUTEA DRAWING NO: Figure Title: ALTERNATIVE ROUTES A & B SCALE (S) : As shown
- 8. ROUTE‐A Elevations Cummulative Distance 845 0 840 255.73 830 389.33 820 539.11 810 677.67 800 852 790 1104.8 780 1258.79 770 1444.2 780 1545.45 790 1629.51 800 1724.94 810 1900.14 820 2048.71 830 2116.51 840 2539.42 850 2645.84 860 2970.87 870 3126.49 880 3299.36 890 3409.6 900 3708.97 910 3846.4 920 4032.08 930 4219.95 940 4407.03 950 4559.27 960 4689.71 970 4826.07 980 4930.36 990 5068.12 995 5322.29
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- 10. ROUTE‐B (DESIGN ROUTE) Elevations Cummulative Distance 845 0 840 336.49 830 529.73 820 727.16 810 938.87 810 1121.88 820 1233.39 830 1781.54 830 2312.28 820 2417.28 830 2510.67 840 2588.7 850 2717.04 860 2816.56 870 2907.1 880 3111.91 890 3255.83 900 3295.93 910 3423.04 920 3599.98 930 3749.73 940 3869.29 950 3952.76 960 4116.65 970 4350.79 980 4528.06 990 4735.71 1000 4919.92
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- 12. SCREENING OF ALTERNATIVES Examination of the profiles of Routes A and B, shown in figure , indicates that both Routes A and B could provide a vertical profile which would conform with the gradient and depth of cut and fill but that Route A requires excessive uphill haul. For this and other reasons indicated in the summary screening process shown in the figure, Route B is the one selected for technical feasibility. SCREEN EVALUATION S No. CRITERIA ROUTE A ROUTE B 1 Length of Route 5322.29 ft 4919 FT 2 Conformance with design controls Full conformance 3 Cut and fill balance There is an even balance Excessive cutting is required 4 Need for bridges or special structures None None 5 Environmental impacts No obvious Environmental impacts Excessive cut & fill will lead to environmental impacts. 6 Potential high cost items None Excessive hauling & digging costs involved 7 Haul direction Satisfactory Excessive uphill hauling. CONCLUSIONS: Route‐A is longer than Route‐B, but Route B requires excessive uphill haul and need to dispose of considerable earthwork off the site. PROCEEDING WITH THE ROUTE‐A FOR ANALYSIS PURPOSES.
- 13. HORIZONTAL ALIGNMENT The horizontal alignment can be developed for alternative B and the relevant dimensions and angles computed and checked. The development of tangent and curve distances may then be converted to stations and an estimate of the traverse closure made to ensure that no gross errors have been made in the scaling of distances and angles. As well as the dimensions of each of the tangent and curve segments of the proposed highway, the stations are computed for points along the centerline of the route. Care must be taken to define clearly the location of the beginning and end points of the proposed route, in this case assumed to be the centerlines of the existing highways. Each curve radius is checked for compliance with the minimum allowable radius of 485ft (According to BDE manual). During this preliminary design stage for this class of highway, no attempt has been made to illustrate the use of transition curves, however, the superelevation curve has been designed and calculated and shown on drawings.
- 14. STA1+00 STA2+00 STA3+00 STA4+00 STA5+00 STA6+00 STA7+00 STA8+00 STA9+00 STA10+00 STA11+00 STA12+00 STA13+00 STA14+00 STA15+00 STA16+00 STA17+00 STA18+00 STA19+00 STA20+00 STA21+00STA22+00STA 23+00 STA 24+00STA 25+00 STA 26+00 STA 27+00 STA 28+00 STA 29+00 STA 30+00 STA 31+00 STA 32+00 STA 33+00 STA 34+00 STA 35+00 STA 36+00 STA 37+00 STA 38+00 STA 39+00 STA 40+00 STA 41+00 STA 42+00 STA 43+00 STA 44+00 STA 45+00 STA 46+00 STA47+00 STA 48+00 STA 49+00 STA 50+00 STA 51+00 STA 53+22.29 STA 53+00 STA 52+00 434.7621 849.4409 660.7152 STA0+00 CURVE #1 CURVE #2 CURVE#3 81.1156° 41.5167° 63.0936° DRAWING NO: Figure Title: HORIZONTAL ALIGNMENT PROPOSED CENTRELINE SCALE (S) : As shown
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- 19. CURVE#1 CURVE#2 CURVE#3 PC= 6+12.13 PC= 13+42.15 PC= 42+61.18 PT= 10+46.89 PT= 21+91.59 PT= 49+21.89 R=600 R=600 R=600 Rmin= v^2 15(e+fs) Rmin= 40^2 =485ft 15(0.06+fs) Rmin= v^2 15(e+fs) Rmin= 40^2 =485ft 15(0.06+fs) Rmin= v^2 15(e+fs) Rmin= 40^2 =485ft 15(0.06+fs) D= 5729.58 = 9.54° 600 D= 5729.58 = 9.54° 600 D= 5729.58 = 9.54° 600 Δ=L*D 100 Δ=434.76*9.54 =41.47° 100 Δ=L*D 100 Δ=849.44*9.54 =81.036° 100 Δ=L*D 100 Δ=660.71*9.54 =63.03° 100 T= Rtan (Δ/2) T= 600tan (41.47/2) = 230.31’ T= Rtan (Δ/2) T= 600tan (81.03/2) = 512.44’ T= Rtan (Δ/2) T= 600tan (63.03/2) = 367.68’ M= R (1‐cos (Δ/2)) M= 600(1‐cos (41.47/2)) M=22.84’ M= R (1‐cos (Δ/2)) M= 600(1‐cos (81.03/2)) M=22.91’ M= R (1‐cos (Δ/2)) M=600(1‐cos (63.03/2)) M=22.68’ E=R (sec (Δ/2)) E=600(sec (41.47/2)) E=42.68’ E=R (sec (Δ/2)) E=600(sec (81.03/2)) E=189.05’ E=R (sec (Δ/2)) E=600(sec (63.03/2)) E=103.69’ C=2RSin (Δ/2) C=2*600Sin (41.47/2) C=424.85’ C=2RSin (Δ/2) C=2*600Sin (81.036/2) C=779.624’ C=2RSin (Δ/2) C=2*600Sin (63.03/2) C=627.26’ Station Chord Cummulative Angle PC = 6+12.13 0 0 7+00 88.72 4.24° 8+00 101.04 9.07° 9+00 101.04 13.9° 10+00 101.04 18.73° PT= 10+46.89 46.89 20.99° (D/2=21°) DRAWING NO. : Title : HORIZONTAL CURVE 1,2 & 3 CALCULATION
- 20. SUPER ELEVATION TRANSITION LENGTH (SETL) Curve 1 SUPER ELEVATION TRANSITION LENGTH (SETL):‐ Lr = (w*n1)ed*bw Δ ed = 5.8% Lr = (12*1)5.8*1 = 120’ 0.58 Lr = 120’ Nc = 1.5 Lt = (Nc/ ed)* Lr Lt = (1.5/ 5.8)* 120 =31.03’ Lt = 31.03’ SETL=151.03 I. Start of Tangent Runout: 12+30.72 II.Start of Super elevation Runoff: 12+61.75 III. Point at which Design Super elevation is attained: 13+81.75 IV. Last Point of Full Design Super elevation: 21+51.4 V. End of Super elevation Runoff: 22+71.99 VI. End of Tangent Runout: 23+03.02
- 21. VERTICAL ALIGNMENT Based upon the horizontal alignment established earlier and incorporating any modifications to it, the profile at the centerline of the proposed highway is plotted shown in the figure. The location and length of all vertical curves and of positive gradients are clearly shown. All the controls (maximum grades, maximum and minimum length of curve, maximum vertical cut and fill dimensions, and approximate balance of cut and fill) have been compiled with. The following summarizes the curve selection process: The minimum length of the curve is based upon stopping sight distance criterion. The maximum length of the curve for this project is based upon the maximum K (=167) value established for the drainage criteria. Select a curve length that is equal to or greater than the minimum length for stopping sight distance criteria and equal to or less than the maximum for the drainage criteria. If the selected length of curve based upon the above considerations is not acceptable when the overall profile is considered, the profile must be examined and adjusted, and the process repeated until all criteria are met.
- 22. VERTICAL CUVE #1 COMPUTATIONS(CREST) 1.1% ‐5.72% Vertical Curve Computations Sag(1) Curve ‐Input ITEM SOURCE VALUE G1 Profile 1% G2 Profile 5.7% PVC Profile 100 PVT Profile 490 L Profile 401 PVI PVC + L/2 300.5 A G2‐G1 6.7 E LA/800 3.35 PVI EI Profile 874.39 PVC EI (PVI EI)‐((G1/100)*(L/2)) 841.34 PVT EI EL of PVC + (G1/100)*L )+ 4E(X/L)2 831.5 XTP G1*L/G2‐G1 59.85 X: Station PVC +X 159.85 XELEV EL of PVC + (G1/100)*X )+ 4E(X/L)2 841.67 DRAWING NO.: TITLE: Vertical Curve 1 computations
- 23. VERTICAL CURVE #2 COMPUTATIONS (SAG) ‐5.7% 5.8% Vertical Curve Computations CREST(1) Curve ‐Input ITEM SOURCE VALUE G1 Profile 5.7% G2 Profile 5.8% PVC Profile 780 PVT Profile 2020 L Profile 1248.07 PVI PVC + L/2 2644.03 A G2‐G1 11.5 E LA/800 17.94 PVI EI Profile 782.43 PVC EI (PVI EI)‐((G1/100)*(L/2)) 818.00 PVT EI EL of PVC + (G1/100)*L )+ 4E(X/L)2 816.00 XTP G1*L/G1‐G2 618.57 X: Station PVC +X 1398.57 XELEV EL of PVC + (G1/100)*X )+ 4E(X/L)2 800.24 DRAWING NO : TITLE: Vertical Curve# 2 Computations
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