CE331 - Design Criteria for Highways and Railways PDF

Topic 3 Design Criteria for Highways and Railways ENGR. JUNE CARLO S. ENCABO CE431- Principles of Transportation Engineering Intended Learning Outcome: Classify different design criteria involving highways, and railways. Explain the principle and science of these criteria. ...

Topic 3 Design Criteria for Highways and Railways ENGR. JUNE CARLO S. ENCABO CE431- Principles of Transportation Engineering Intended Learning Outcome: Classify different design criteria involving highways, and railways. Explain the principle and science of these criteria.  5 Human Factor and Driver’s Performance Vehicles Traffic Characteristics CHARACTERISTICS Physical Elements in improving design of Highways & Railways Economic Factors  5 CHARACTERISTICS Read More:  Anticipated Traffic Volume Character of Traffic Design Speed DESIGN CONTROLS of Highway Construction Design Traffic (Vehicles) Highway Capacity Classification of Highway Accident Information  DESIGN CONTROLS of Highway Construction A road should be designed so that it will accommodate or can be readily changed to accommodate the number of vehicles which is estimated to pass it towards the end of its life. This number is called the design volume. Anticipated Traffic Volume In estimating the design volume, the minimum life is commonly assumed to be 10 to 15 years for a flexible pavement, and 20 years for a rigid pavement. The design traffic data should include the following elements: ADT – current/future average daily traffic, year specified. DHV – future design hourly volume, two-way unless otherwise specified (DHV usually equals 30 HV). K – Ratio of DHV to ADT; generally 12% to 18% for Rural and 8 to 12% for Urban. D – Directional distribution of DHV, one-way volume in predominant direction of travel expressed as percentage of total. D normally varies from about 50 to 80% of two-way DHV, with an average of 67%. T – Trucks, exclusive of light delivery trucks, expressed as a percentage of DHV. As an average on main rural highways, T is 7 to 9% of DHV and 13% of ADT; where weekend peaks govern, the average may be 5% to 8% of DHV.  EXAMPLE: DESIGN CONTROLS of Highway Construction The table shows a 15 minute volume counts during the peak hour on an approach of an intersection Time Volume of Traffic 6:00-6:15 pm 375 6:15-6:30 pm 380 Anticipated Traffic Volume 6:30-6:45 pm 412 6:45-7:00 pm 390 Determine Peak Hour Volume; Determine Peak Hour Factor; Determine Design Hourly Volume (DHV); The design traffic data should include the following elements: ADT – current/future average daily traffic, year specified. DHV – future design hourly volume, two-way unless otherwise specified (DHV usually equals 30 HV). K – Ratio of DHV to ADT; generally 12% to 18% for Rural and 8 to 12% for Urban. D – Directional distribution of DHV, one-way volume in predominant direction of travel expressed as percentage of total. D normally varies from about 50 to 80% of two-way DHV, with an average of 67%. T – Trucks, exclusive of light delivery trucks, expressed as a percentage of DHV. As an average on main rural highways, T is 7 to 9% of DHV and 13% of ADT; where weekend peaks govern, the average may be 5% to 8% of DHV. DESIGN CONTROLS of Highway Construction All roads should be designed to accommodate trucks, buses, passenger vehicles, handcarts, cyclists and pedestrians with safety and convenience. Character of Traffic Four general classes of design vehicles are (1) Passenger cars; (2) Buses; (3) Trucks, and (4) Recreational vehicles. DESIGN CONTROLS of Highway Construction The design speed is the speed determined for design and correlation of the physical features of a highway that influence vehicle operation. Design Speed The choice of design is influenced principally by the character of terrain, the extent of man-made features and economic considerations. DESIGN CONTROLS of Highway Construction The operating characteristics of motor vehicles should be considered in analyzing a facility. Design Traffic (Vehicles) The forces that must be overcome by motor vehicles if they are to move are rolling, air, grade, curve, and inertial resistance. DESIGN CONTROLS of Highway Construction Roadway conditions include geometric and other elements. In some cases, these influence the capacity of Highway Capacity a road; in others, they can affect a performance measure such as speed, but not the capacity or maximum flow rate of the facility. DESIGN CONTROLS of Highway Construction Certain characteristics distinguish multilane suburban and rural highways from expressways. Classification of Highway For example, vehicles may enter or leave multilane highways at intersections and driveways, and they can encounter traffic signals. DESIGN CONTROLS of Highway Construction On all proposed projects, the accident history should be analyzed and potentially hazardous features and locations identified to determine appropriate safety enhancement. Accident Information A study of accidents by location, type, severity, contributing circumstances, environmental conditions, and time periods may suggest possible safety deficiencies.  Accident Information DESIGN CONTROLS of Highway Construction 𝑨 (𝟏𝟎𝟎, 𝟎𝟎𝟎, 𝟎𝟎𝟎) 𝑹= 𝑨𝑫𝑻 𝒙 𝑵 𝒙 𝟑𝟔𝟓 𝒙 𝑳 Accident rates for 100 million vehicle miles of R = the accident rate for 100 million vehicle miles travel (HMVM) for a segment A = the number of accidents during period of analysis ADT = average daily traffic of highway N = time period in years L = length of segment in miles  Accident Information DESIGN CONTROLS of Highway Construction 𝑨 (𝟏, 𝟎𝟎𝟎, 𝟎𝟎𝟎) 𝑹= 𝑨𝑫𝑻 𝒙 𝑵 𝒙 𝟑𝟔𝟓 Accident rates per million entering vehicles (MEV) for R = the accident rate for one million entering vehicles an intersection A = the number of accidents during period of analysis ADT = average daily traffic entering the intersection from all legs N = time period in years  Accident Information DESIGN CONTROLS of Highway Construction Severity Ratio 𝒇𝒂𝒕𝒂𝒍 + 𝒊𝒏𝒋𝒖𝒓𝒚 𝒂𝒄𝒄𝒊𝒅𝒆𝒏𝒕𝒔 = 𝒇𝒂𝒕𝒂𝒍 + 𝒊𝒏𝒋𝒖𝒓𝒚 + 𝒑𝒓𝒐𝒑𝒆𝒓𝒕𝒚 𝒅𝒂𝒎𝒂𝒈𝒆 DESIGN CONTROLS of Highway Construction The accident rate at a sharp highway curve was 1240 per EXAMPLE PROBLEM million passing vehicles. In the last 5 years, there had been 2607 accidents. What was the average daily traffic? DESIGN CONTROLS of Highway Construction Data on traffic accident recorded for the past 5 years on a certain stretch of a two lane highway is tabulated as follows. Determine the Severity Ratio. Property Year Damage Injury Fatal EXAMPLE PROBLEM 1960 110 42 4 1961 210 54 2 1962 182 60 5 1963 240 74 7 1964 175 94 6