The sole objective of the process is to minimize future road accident occurrence and severity once the scheme has been built and the road comes into use. The identification of potential safety hazards on new road project at the appropriate Type, so that they can be eliminated or otherwise treated to mitigate their adverse effect at minimum cost .To decrease the rate of accidents at a particular location. The identification of potential safety hazards features of an existing road so that they can be eliminated or otherwise treated before they become accident prone location.
Road safety audit is formal procedure for assessing accident potential and safety performance in the provision of new road schemes, the improvement and rehabilitation of existing road & in maintenance of roads. The role of auditor is to provide independent advice in the form of written recommendations. The designer or client then considers the advice and formal decision is made by them on whether or not to adopt each of the recommended safety alterations. The primary role of audit team is to identify the potential problems of a highway project by conducting the site inspection & collecting data from various agencies.
Road Safety Audit (RSA) is a formal procedure for assessing accident potential and safety performance in the provision of new road schemes and schemes for the improvement and maintenance of existing roads.
Road safety audit procedures were developed in 1989 by British traffic engineers and evolved from a tool used by railway engineers to examine safety issues on railways. RSA’s were soon adopted by Australia, New Zealand, Denmark, and many other developed countries in the early 1990s (FHWA 2009a). The development of the road safety audit procedures was refined before adoption by the American transportation community. In 1996, the FHWA sponsored a tour of Australia and New Zealand to study their road safety audit programs to learn strategies on how to implement road safety audits in the United States. From the lessons learned, FHWA sponsored a road safety audit workshop in St. Louis to develop procedures to be used in the road safety audit pilot program. The first pilot program included thirteen states and provided a basis for use of road safety audits in the United States (Wilson and Lipinski 2004). As road safety audits have gained popularity in the United States they have also gained recognition and acceptance in other parts of the world. The Asian Development Bank, in collaboration with United Nations Economic Commission for Europe and the World Bank, has recently sponsored the use of road safety audits and have a published their own toolkit to be used in conducting a road safety audit (ADB 2003). Countries around world are starting to realize the low cost tool of saving lives. There are two different RSA processes that can be used. The first one is the traditional RSA that looks at projects before they are built or operational, Pietrucha et al. (2001) described a road safety audit as a process where a team of experts attempts to 9 identify features of the roadway operating environment as potentially dangerous and work to eliminate or change those features in different parts of the design process. The other RSA process used and the process that is used throughout this research is called Road Safety Audit Reviews (RSARs) and can be defined as “an evaluation of an existing roadway section by an independent team, focusing solely upon safety issues” (Wilson and Lipinski 2004). Most states DOTs have reactive safety programs that focus on highcrash locations or have black spot treatment programs. RSARs are different in that they are proactive in nature and use crash data when available but are not dependent on it. RSARs focuses more on safety issues associated with the roadway, all road users, operating under all environmental conditions, and to identify the safety issues associated with the existing facility (Wilson and Lipinski 2004).
A road safety audit is the continuous monitoring of the safety factor of new and existing highway and traffic management scheme, which involve improvement of existing layout. The fundamental goal of road safety audit is to insure that there is less future problems on highway. A accidents are occurs due to collision of two or more vehicles, cyclist and vehicle, pedestrian and vehicle, fixed object and vehicle, overturned vehicle near public road, etc. in our routine life as the transportation is increasing it will also increase safety issue in this area of extensive research and work. In developing countries like India, the road accidents increasing year by year. So it is necessary to reduce road accident and work towards the road safety. To apply the road safety audit in real life, the first thing is to know the geometric features of highways.
This accidents will effect of people for a long time. The Gujarat State Road Transport Corporation provides facility of transportation to approximately 24 lakh people every day. Road safety audit provides to assess the road accident and will give the better sa than cure”. For improving road safety audit will the work road on new roads , safety,
Existing road sand therefore the maintenance of the existing road. Road safety audit contained the internal part of designing, planning, construction maintenance of road, this will become the compulsory rule for newly road.
In past, there is no priority to road safety audit but now a days India also started believing in the importance of road safety audit .because of this Ministry of Road Transport and Highway sponsored the project Under this project, Manual for Road Safety Audit has been prepared. First Road Safety Audit was carried again by CRRI IN 2000 on Indore Bypass.
1.2 Scope of Road safety audit
India has the second largest road network in the world with over 3 million kms of roads of which 60% are paved. These roads make a vital contribution to India’s economy. On the whole, however, the facilities for the road users fall far behind acceptable standard, leading to a huge death toll resulting from road accidents. In recent times, there has been a growing concern over the road safety problem.
The Road Safety problem in India demands a multidimensional approach. Road Safety Audit is only one important component: Subcontracts India is doing ground breaking work in the following areas:
1.3 Road safety audit Phases
a. Completion of preliminary design, preferably prior to the submission for planning permission
b. Completion of detailed design, usually before the tender documents have been submitted
c. Completion of construction prior to opening (or completion if on a ‘live’ highway)
d. Collision monitoring (12 months and 36 months after opening of the highway scheme)
1.4 Types of Road safety audit
There are four different Types of a Road Safety Audit each forming their own independent report but refer to each other and these are detailed below:-
Type 1 Road Safety Audits are undertaken at the completion of preliminary design and where possible, before planning consent is granted. This is the last occasion at which land requirements may be increased and it is therefore essential to consider fully any road safety issues which may have a bearing upon land take before planning consent is granted. At the Road Safety Audit Type 1 all team members shall visit together and examine the existing highway layout or features and where the new highway improvement scheme ties into the existing highway.
Type 1 – Completion of Preliminary Design
• Will the new road drain adequately
• Can all accesses be used safely
• Are horizontal and vertical alignments consistent with required visibility
• Is provision for right turning vehicles required
• Have pedestrian and cycle routes been provided where required
• Are lighting columns located at new junctions and where adjoining existing roads
• Are any road markings proposed at this Type appropriate
Type 2 Road Safety Audits are undertaken at completion of the detailed design Type of the works. The Audit Team will be able to consider the layout of junctions, position of signs, carriageway markings, lighting provision and other issues. At the Road Safety Audit Type 2 all team members shall visit together and examine the existing highway layout or features and where the new highway improvement scheme ties into the existing highway.
Type 2 – Completion of Detailed Design
• General basic design principals
• Local alignment
• Junctions layout and visibility
• Non motorized user provision
• Road signs, carriageway markings and lighting
The Type 3 Road Safety Audit should be undertaken when the Highway Improvement Scheme is substantially complete and preferably before the works are open to road users. The Audit Team will examine the scheme site during daylight and during the hours of darkness, so hazards particular to night operation can also be identified. The Audit Team Leader shall invite representatives of the Police, the Local Authority and Maintaining Agent to accompany the Audit Team to offer their views for the Type 3 Audit.
Type 3 – Completion of Construction
• The Audit Team should consider whether the design has been properly translated into the scheme as constructed and that no inherent road safety defect has been incorporated into the works.
• Particular attention should be paid to design changes which have occurred during construction.
• Design principles
• Local Alignment
• Junction layouts
• Non motorized user provision
• Road signs, carriageway markings and lighting
Type 4 – (Monitoring)
During the first year a Highway Improvement Scheme is open to traffic, a check should be kept on the number of personal injury collisions that occur, so that any serious problems can be identified and remedial work arranged quickly. Type 4 collision monitoring reports shall be prepared using 12 months and 36 months collision data from the time the scheme became operational.
These reports shall be submitted to the Overseeing Organization. The collision records shall be analyzed in detail to identify:
• Locations at which personal injury collisions have occurred
• Personal injury collisions that appear to arise from similar causes or show common factors.
The sole objective of the process is to minimize future road accident occurrence and severity once the scheme has been built and the road comes into use.
• The identification of potential safety hazards on new road project at the appropriate Type, so that they can be eliminated or otherwise treated to mitigate their adverse effect at minimum cost.
• To decrease the rate of accidents at a particular location.
• The identification of potential safety hazards features of an existing road so that they can be eliminated or otherwise treated before they become accident prone location.
1.6 Road geometry design
Geometric design deals with the visible elements of a highway. Adoption of proper geometric standards facilitates safe and economical operation of vehicles. Geometric design is influenced by a number of factors among which nature of terrain, type, composition and volume of traffic, operating speed, land-use characteristics and aesthetics are important.
A draft for this document was initially prepared by the IRC Secretariat. This was considered by the Traffic Engineering Committee (personnel given below) in their meeting held onthe 4th and 5th October, 1978 which approved the same subject to certain modifications to be carried out by Dr. N.S. Srinivasan and K. Arunachalam. The draft so modified was approved by the Specifications and Standards Committee in their meeting held on the 24th May, 1983, and later by the Executive Committee and Council in their meetings held on the 21st July, 1983 and 21st August, 1983 respectively.
GEOMETRIC DESIGN AND GENERAL FEATURES
(i) This Section lays down the standards for geometric design and general features for upgrading the existing state highways/major district roads to two-lane with or without paved shoulders.
(ii) (a) Stretches passing through built up areas shall normally be provided with 4-lane divided carriageway . Such stretches shall be indicated in Schedule-B of the Concession Agreement. Additional land, if any, required for 4-laning shall be acquired by the Government and where the land is yet to be acquired, the date of handing over the land to the Concessionaire shall be indicated.
(b) Where there are constraints of existing ROW width or difficulty in acquiring land along the existing alignment in built up areas, the Government may specify construction of a bypass instead of 4-laning. The alignment of the bypass shall be specified by the Government. The land for the bypass shall be acquired by the Government and where the land is yet to be acquired, the date of handing over the land to the Concessionaire shall be indicated. The bypass shall be access controlled, unless specified otherwise. In case, the Government decides to provide two-lane carriageway for the bypass, the same shall be placed eccentrically with respect to the ROW to facilitate proper widening to four lanes in future.
(iii) The geometric design of the Project Highway shall conform to the standards set out in this Section as a minimum. The Concessionaire shall ensure that liberal geometric standards are followed to the extent feasible within the given Right of Way.
(iv) As far as possible, uniformity of design standards shall be maintained throughout the length. In case of any change, it shall be affected in a gradual manner.
(v) Where the existing road geometrics are deficient with respect to minimum requirements and its improvement to the prescribed standards requires acquisition of additional land, such stretches shall be specified in Schedule-B of the Concession Agreement. Additional land as required shall be provided by the Government. pc/coi 11 12 IRC:SP:73-2007 MANUAL OF SPECIFICATIONS AND STANDARDS
(vi) Existing horizontal curves, which are found deficient in radius, layout, transition lengths or super elevation shall be corrected to the specified standards.
(vii) Any deficiencies in the vertical profile in respect of grades, layout of vertical curves and sight distance shall be corrected to meet the minimum specified requirements.
1.7 Scope of road geometry design
These standards are applicable to urban roads in plains. These are also applicable to roads in suburban areas. These however do not cover standards for urban expressways.
All the main elements of geometric design for urban roads are included in the text. Layout of junctions are not covered as standards for the same are proposed to be brought out
1.8 Classification of urban roads ,Definitions and functions
For the purpose of geometric design, urban roads other than expressways are classified into four main categories.
(iii) Collector Street
(iv) Local Street
This publication deals with standards for all categories of roads except Expressways for which separate standard is proposed to be evolved.
(i) Arterial : A general term denoting a street primarily for through traffic, usually on a continuous route.
(ii) Sub-arterial : A general term denoting a street primarily for through traffic usually on a continuous route but offering somewhat lower level of traffic mobility than the arterial.
(iii) Collector Street : A street for collecting and distributing traffic from and to local streets and also for providing access to arterial streets.
(iv) Local Street : A street primarily for access to residence, business or other abutting property.
Functions of different categories of urban roads are give below:
(i) Arterials : This system of streets, along with expressway where they exist, serves as the principal network f 2 IRC : 86-1983 through traffic flows. Significant intra-urban travel such as between central business district and outlying residential areas or between major suburban centers takes place on this system. Arterials should be coordinated with existing and proposed expressway systems to provide for distribution and collection of through traffic to and from sub-arterial and collector street systems. Continuity is essential for arterials to ensure efficient movement of through traffic.
A properly developed and designated arterial street system would help to identify residential neighborhoods, industrial sites and commercial areas. These streets may generally be spaced at less than 1.5 km in highly developed central business areas and at 8 km or more in sparsely developed urban fringes. The arterials are generally divided highways with full or partial access. Parking, loading and unloading activities are usually restricted and regulated. Pedestrians are allowed to cross only at intersections.
(ii) Sub-arterials : These are functionally similar to arterials but with somewhat lower level of travel mobility. Their spacing may vary from about 0.5 km in the central business district to 3—5 km in the sub-urban fringes.
(iii) Collector Streets: The function of collector streets is to collect traffic from local streets and feed it to the arterial and sub-arterial streets or vice-versa. These may be located in residential neighborhoods, business areas and industrial areas. Normally, full access is allowed on these streets from abutting properties. There are few parking restrictions except during the peak hours.
(iv) Local Streets : These are intended primarily to provide access to abutting property and normally do not carry large volumes of traffic. Majority of trips in urban areas either originate from or terminate on these streets.
(v) Local streets may be residential, commercial or industrial, depending on the predominant use of the adjoining land. They allow unrestricted parking and pedestrian movements.
1.In carrying out the safety audit of the road project following methodology was adopted, the sequence of steps are as shown in Figure .
• The Information relating to the design standards adopted for the road project was obtained from NHAI.
• Detailed engineering drawings of the road were requested from the NHAI in form of hard as well as soft copies to get an idea of the project from the point of adequacy in design. Road Safety Audit of National Highways in India at Construction Stage Dr. Kayitha Ravinder & Dr Jakkula Nataraju 13th WCTR, July 15-18,2013 – Rio de Janeiro, Brazil 4
• Field visits were made by driving / walking along the project road to appreciate other physical and environmental features that required special attention from the point of view of safety during day time as well as night time. Some typical aspects studied include pedestrians, roadside developments and sociological aspects which needed special attention focusing on provision of appropriate facilities. RSA Checklists (IRC-SP-88:2010) was taken to ensure that problems and situations that can affect the road safety at the desired stage of road safety audit have been taken into consideration. These checklists broadly covered the aspects like
Fig.: Methodology adopted for Road Safety Audit at Pre-opening stage Whether information regarding the construction zone approaching has been provided well in advance or not.
• Whether standard procedure and contract conditions provided for proper management of the construction site and road users are properly and safely accommodated.
• Whether the transitions from the existing road to the road works safe and clearly laid out.
• Whether the width of the lanes is satisfactory for the traffic passing through the works area. • Whether sight and stopping distances adequate at works and at intersections.
• Whether bus stops appropriately located with adequate clearance from the traffic lane for safety and visibility.
• Whether appropriate street lighting or other delineation provided at the road works to ensure that the site is safe at night. Check the night time visibility of traffic control devices.
Check for proper education and training programmed for site operators and managers, which would assist in creating and maintaining safer environment for construction workers and road users.
• For clear and sufficient information to the road user, advance warning signs installed or not.
• Is there any provision of marked lanes for safe and clearly guiding road users.
• Whether suitable measures provided through construction zones to control driver behavior.
• Check for the adequacy of traffic control devices (such as signs, markings, cones, drums, delineators, barricades, flashing lights etc.) required for each zone i.e., at advance warning zone, at approach transition zone and at work zone? Check for placement and visibility of these control devices.
• Has permission been taken while changing the standard layouts from safety point of view.
• Whether police and other emergency services been consulted. Appropriate recommendations / remedial measures for the identified safety deficiencies during the construction stage was provided or not, was checked conforming to IRC-SP88:2010. However, some of the important safety audit observations at construction stage have been discussed in the subsequent sections in brief.
2. Safety Audit can be applied to a) New Roads b) Existing / constructed Roads. On new roads or roads to be improved or built, the audit will lead to identification of accident prone situations and on existing or already constructed roads, the audit will suggest appropriate mitigation measures to reduce the possibility of accidents.
Road Safety Audit (RSU) basically comprises of three (3) Stages:
Stage 1 – Audit during design and planning
Stage 2 – Audit during Construction
Stage 3 – Audit after the completion of the project
In the present context, since Stage 1 (design and planning) has been completed in most of the stretches, an audit in real terms is not possible. However, the designers can best identify the shortfall in the designs and the reasons thereof. Hence the requirement of ‘Non compliance report for rural roads design’ should be completed by the PIUs/PICs.
Stage 2 is generally carried out during construction as temporary measure on high volume highways / roads in urban area, and is not essential for low volume ODR’s. However, the PIUs/PIC’s (as it requires continuous monitoring, considered to be beyond the scope of PMC) may carryout such an audit based on IRC SP 55-2001.
Stage 3 is carried out in completed stage of the project and PIUs/PIC’s who are at site, should carrying out the same for the entire completed road stretch as per the Format provided for ‘Non Compliance Report For Rural Roads After Completion’.
The RSA would be based on the above feedback from PICs, and Site Reconnaissance, wherever completed, and required mitigation measures may be implemented.
3.1 Methodology of Horizontal and Vertical Alignment
Center line alignment influences haul cost, construction cost, and environmental cost (e.g., erosion, sedimentation). During the reconnaissance phase and pre-construction survey the preliminary center line has been established on the ground. During that phase basic decisions regarding horizontal and vertical alignment have already been made and their effects on haul, construction, and environmental costs. The road design is the phase where those “field” decisions are refined, finalized and documented.
3.1.1 Horizontal Alignment Considerations
The preferred method for locating low volume roads discussed in Section 2.3, the so called non-geometric or “free alignment” method, emphasizes the importance of adjusting the road alignment to the constraints imposed by the terrain. The main difference between this and conventional road design methods is that with the former method, the laying out and designing of the centerline offset is done in the field by the road locator while substantial horizontal offsets are often required with the latter method (Figure .
Non-geometric and conventional p-line traverses.
Adjustments in horizontal alignment can help reduce the potential for generating roadway sediment. The objective in manipulating horizontal alignment is to strive to minimize roadway cuts and fills and to avoid unstable areas. When unstable or steep slopes must be traversed, adjustments in vertical alignment can minimize impacts and produce a stable road by reducing cuts and fills. The route can also be positioned on more stable ground such as ridgetops or benches. Short, steep pitches used to reach stable terrain must be matched with a surface treatment that will withstand excessive wear and reduce the potential for surface erosion. On level ground, adequate drainage must be provided to prevent ponding and reduce subgrade saturation. This can be accomplished by establishing a minimum grade of 2 percent and by rolling the grade.
Achieving the required objectives for alignment requires that a slightly more thoughtful preliminary survey be completed than would be done for a more conventionally designed road. There are two commonly accepted approaches for this type of survey: the grade or contour location method (used when grade is controlling), or the centerline location method (used when grades are light and alignment is controlling). Figure illustrates design adjustments that can be made in the field using the non-geometric design concept discussed earlier.
Figure Design adjustments.
Equipment needed for ether method may include a staff compass, two Abney levels or clinometers, fiberglass engineer’s tape (30 or 50 m), a range rod, engineering field tables, notebook, maps, photos, crayons, stakes, flagging, and pencils. The gradeline or contour method establishes the location of the P-line by connecting two control points with a grade line. A crew equipped with levels or clinometers traverses this line with tangents that follow, as closely as possible, the contours of the ground. Each section is noted and staked for mass balance calculations. Centerline stakes should be set at even 25 – and 50 – meter stations when practicable and intermediate stakes set at significant breaks in topography and at other points, such as breaks where excavation goes from cut to fill, locations of culverts, or significant obstructions.
On gentle topography with slopes less than 30 percent and grade is not a controlling factor, the centerline method may be used. Controlling tangents are connected by curves established on the ground. The terrain must be gentle enough so that by rolling grades along the horizontal alignment, the vertical alignment will meet minimum requirements. In general, this method may be less practical than the gradeline method for most forested areas.
When sideslopes exceed 50 – 55 percent or when unstable slope conditions are present, it may be necessary to consider full bench construction shown in Figure . Excavated material in this case must be end hauled to a safe location. Normally, the goal of the road engineer is to balance earthwork so that the volume of fill equals the volume of cut plus any gain from bulking less any loss from shrinkage Figure.
Road design, through its elements such as template (width, full bench/side cast), curve widening and grade affect the potential for erosion. Erosion rates are directly proportional to the total exposed area in cuts and fills. Road cuts and fills tend to increase with smooth, horizontal and vertical alignment. Conversely, short vertical and horizontal tangents tend to reduce cuts and fills. Erosion rates can be expected to be lower in the latter case. Prior to the design phase it should be clearly stated which alignment, horizontal or vertical, takes precedence. For example, if the tag line has been located at or near the permissible maximum grade, the vertical alignment will govern. Truck speeds in this case are governed by grade and not curvature. Therefore, horizontal alignment of the center line can follow the topography very closely in order to minimize earthwork. Self balancing sections would be achieved by shifting the template horizontally.
Figure . Full bench design
Figure . Self-balanced design.
3.1.2 Curve Widening
Roadway safety will be in jeopardy and the road shoulders will be impacted by off-tracking wheels if vehicle geometry and necessary curve widening are not considered properly. Continually eroding shoulders will become sedimentation source areas and will eventually weaken the road. On the other hand, over design will result in costly excessive cuts and/or fills.
The main principle of off-tracking and hence curve widening, centers on the principle that all vehicle axles rotate about a common center. Minimum curve radius is vehicle dependent and is a function of maximum cramp angle and wheelbase length (see Figure ).
Figure . Basic vehicle geometry in off-tracking.
3.1.3 Vertical Alignment
Vertical alignment is often the limiting factor in road design for most forest roads. Frequently grades or tag lines are run at or near the maximum permissible grade. Maximum grades are determined by either vehicle configuration (design/critical vehicle characteristic) or erosive conditions such as soil or precipitation patterns. Depending on road surface type, a typical logging truck can negotiate different grades. Table 16 lists maximum grades a log truck can start from. It should be noted that today’s loaded trucks are traction limited and not power limited. They can start on grades up to 25 % on dry, well maintained, unpaved roads. Once in motion they can typically negotiate steeper grades.
Vertical curves or grade changes, like horizontal curves, require proper consideration to minimize earthwork, cost, and erosion damage. Proper evaluation requires an analysis of vertical curve requirements based on traffic characteristics (flow and safety), vehicle geometry, and algebraic difference of intersecting grades.
Vertical curves provide the transition between an incoming grade and an outgoing grade. For convenience in design, a parabolic curve (Figures is used because the grade change is proportional to the horizontal distance. The grade change is the difference between incoming grade and outgoing grade. The shorter the vertical curve can be kept, the smaller the earthwork required.
Figure . Typical vertical curves (VPI = Vertical Point of Intersection).
Clearances are required to be provided for overhanging loads and the tilting of vehicle towards obstruction by crossfall or superelevation of carriageway and for kerb shyness. Standards for lateral clearances for underpasses on urban roads are given in para 7 of IRC : 54-1974 ‘ Lateral and Vertical Clearances at Underpasses for Vehicular Traffic”. The same are recommended between edge of carriageway and obstruction on footpath, verge or central reserve. Where an obstruction is located on the inside of a bend, a greater clearance than that specified may be required to ensure that the sight distance is not less than the minimum. Broad standards for clearances are reproduced in paras through
(i) Underpass for Vehicles
Lateral Clearances : The lateral clearances from the edge of pavement should be as follows :
(a) Pavement without footpath
Minimum clearances from the edge of pavement
Arterial and sub-arterial … 1 m
Collector and local streets … 0.5 m
(b) Pavement with footpath
No extra clearance beyond the footpath is necessary.
(c) Clearance on divided carriageway
The left side clearances should be followed on the same lines as above. The right side clearance to the face of any structure in the central median shall be as follows : Arterial and sub-arterial … 1 m from the edge of pavement Collector and local streets … 0.5 m from the edge of pavement Vertical Clearance Minimum vertical clearance on urban roads should be 5.5 m.
(ii) Pedestrian Subway
The minimum width of pedestrian subway is 2.5 metres. The minimum vertical clearance over such subway is 2.5 m.
(iii) Cycle Subway
The minimum width of underpass for cycles is 2.5 m. The minimum vertical clearance for cycle tracks is 2.5 m.
(iv) Combined Cycle and Pedestrian Subway
The width of pedestrian-cum-cycle subway should be 5 m minimum for one-way traffic and 6.5 m for two-way traffic. The minimum height should be 2.5 m.
Chapter-6 STANDARDS AND SPECIFICATIONS OF ROAD GEOMETRY DESIGN
The requirements stated in the Manual for the design of the Project Highway are the minimum. The Concessionaire will, however, be free to adopt international practices, alternative specifications, materials and standards to bring in innovation in the design and construction provided they are comparable with the standards prescribed in the Manual. The Specifications and techniques which are not included in the MOSRTH Specifications/IRC Specifications/State PWD Specifications shall be supported with authentic standards and Specifications like AASHTO, Euro Codes, British Standards and Australian Code etc. Such a proposal shall be submitted by the Concessionaire to the Independent Engineer for review and comments, if any. In case, the Independent Engineer is of the opinion that the proposal submitted by the Concessionaire is not in conformity with any of the international standards or codes, then he will record his reasons and convey the same to the Concessionaire for compliance. A record shall be kept by the Independent Engineer, of the non-compliance by the Concessionaire of the minimum Specifications and Standards specified in the Manual and shall be dealt with in terms of the provisions of the Concession Agreement. The Concessionaire shall be responsible for adverse consequences, if any, arising from any such noncompliance.
Design Standards Design standards shall be as per IRC:SP:41. Salient features are given below:
INTERSECTIONS AND GRADE SEPARATORS
(i) Design Speed: The approach speed shall be taken as the design speed adopted for the section of Project Highway on which the intersection is located. The design speed for various elements of the intersection shall be taken as 60% of the approach speed. (ii) Design Traffic Volume: The traffic volume for the design of intersection and its distribution at peak hours shall be assessed, up to the operation period, taking into consideration the past trend, likely new development of land, socioeconomic changes, etc. INTERSECTIONS AND GRADE SEPARATORS pc/coi 29
(ii) Design Vehicle: Semi-trailer combination (refer IRC: 3) shall be used in the design of intersections.
(iii) The number of lanes to be provided at the intersection shall be governed by peak hour traffic volume in each direction of travel. For single lane movements, a minimum width of 5.5 m is to be adopted. For two-lane roads between kerbs, a minimum 7.5 m width shall be provided. Widening of carriageway shall be achieved by a taper of not less than 1 in 15.
(iv) Type and radius of curve of intersection: The type and radii of curves would depend upon the types of vehicles turning at the intersection and shall be decided based on the traffic data.
(v) Visibility at intersection: A minimum safe stopping sight distance, appropriate for the approach speeds, shall be available for the traffic on the Project Highway.
Traffic Control Devices
(i) Road markings: Typical road markings for road intersection as given in IRC:SP:41 and IRC:35 shall be followed. The specifications of road markings shall be as given in Section 9 of this Manual.
(ii) Signs: Traffic signs at the junctions shall be provided as per IRC: 67 and Section 9 of this Manual.
(iii) ( Reflectors: To guide the traffic, reflectors in the form of cat’s eyes, delineators, etc shall be provided, in addition to the road markings, especially at the channelising islands.
The design and construction of road embankment and cuttings shall meet the requirements, standards and specifications given in this Section. This Section also covers specifications for subgrade and earthen shoulders.
Where the Project Highway involves improvement to an existing road, efforts should be made to remove the inherent deficiencies in plan, profile and the roadway width. It shall be ensured that the final centre line of the road and the road levels are fixed with great care, duly considering all the relevant factors covering structural soundness, safety and functional requirements.
The existing roadway, where deficient, shall be widened to the roadway width in accordance with para 2.6.
• The existing roads in the States are generally flexible pavements and their capacity augmentation by way of widening and strengthening would therefore generally be by provision of flexible pavements only.
• Situations may, however, also arise where the Government may require provision of cement concrete pavement depending upon specific site conditions. Such a requirement shall be specified in Schedule-B of the Concession Agreement and indicated as a deviation in Schedule-D of the Concession Agreement. The minimum design and maintenance requirements for cement concrete pavement shall be specified by the Government and Schedule-K of the Concession Agreement shall be modified accordingly.
• Design of new pavement sections or widening and strengthening of existing pavements shall take into account all relevant factors for assuring reliable performance that satisfies the specified minimum performance requirements.
• The pavement condition and other data furnished by the Government are based on preliminary investigations. The Concessionaire shall undertake the necessary soil, material and pavement investigations and traffic volume and axle load studies in accordance with the good industry practice for preparing detailed designs.
• The materials, mixes and construction practice shall meet the requirements prescribed herein and MOSRTH Specifications / IRC Specifications, unless specified otherwise.
• Where problematic conditions such as expansive soils, swamps or marshes, flooding, poor drainage, etc. are found to exist, adequate measures shall be adopted to deal with such site conditions.
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