University Of Al-Qadis College of Engineering Department of Roads and Transport Examiner: Dr. Jalal T. S. Al-Obaedi Class: 1 Subject: Principles of roads and transport Eng. Time: 90 minutes Date: 20/0112014 Note: Answer all questions Answer about four only from the following: (40 marks) 1. What are the main modes of transport? And briefly describe the effect of distance traveled on the selected travel modes. Define the following terms used in traffic engineering: (a) space mean speed (b) time mean speed (c) clear spacing (d) gap headway Briefly describe the highway classifications with using a suitable graph Define LOS and describe its types using a suitable graph. Draw simple graphs showing speed-flow, speed-density and flow-density relationships. Q2: Traffic volumes have been collected on a highway as shown in the Table below: (30 marks) Time Iars Buses and trucks the following: Find l- Peak hour factor (PHR) 2- Volume and flow rates for traffic measured in units of (veh/hr) 3- Volume and flow rates for traffic measured in units of (pcu/hr) equivalency factor for trucks and buses is 1.5 cardensity.average time headway during the period (7:45-8:00) Q3: The speeds of two sets of data were 70 (when the flow rate was 1500 veh/hr). Estimate the following: l- The capacity of the highway 2' The average speed of traffic when the flow rate is 1300 veh/hr.
University Of Al-Qadisiya College of Engineering Department of Roads and Transport Examiner: Dr. Jalal T. S. Al-Obaedi Subject: Principles of roads and transport Eng. Time: 90 minutes Date: 2010112014 Note: Answer all questions Answer about four only from the following: lirst GoursG lxamination 2013-2014 tlnswersl (40 marks) l. What are the main modes of transport? And briefly describe the effect of distance traveled on the selected travel modes. Modes of Transportation o land (highways and railways) o Airways o Waterways. Pipe ways Transportation modes choose with distance traveled o walking for short distances. car for medium distances o airplane for long distances 2. Define the following terms used in traffic engineering: (a) space mean speed (b) time mean speed (c) clear spacing (d) gap headway Space mean speed: A statistical term denoting an average speed based on the average travel time of vehicles to traverse a segment of roadway. Time mean speed (spot speed): The arithmetic average of speeds of vehicles observed passing a point on a highway; also referred to as the average spot speed. The individual speeds of vehicles passing a point are recorded and averaged arithmetically. Clear spacing Clear spacing is the difference in length between the following vehicle. Gap headway is usually expressed Gap Headway ilt= Gap headway is the difference in time between the time the rear following vehicle. Gap headway is usually expressed in seconds. time the rear of the leading vehicle and the front of the in feet or meter. of the leading vehicle and the front of the 3. Briefly describe the highway classifications with using a suitable graph 1- Arterial highways provide direct service between cities and larger towns (e.g. Freeways). 2- Collector roads: serve small towns directly and connect them to the arterials. 3- Local roads: serve individual farms and other rural land uses and distribute traffic from/to the collector roads.
4. Define LOS and describe its types using a suitable graph. Level of service (LOS) Lrill.rgi.,,. Level of service (LOS) is a qualitative measure describing operational conditions within a traffic stream and their perception by drivers and/or passengers. speed ratio
Q2: Traffrc volumes have been collected on a highway as shown in the Table below: (30 marks) Time Ears Buses and trucks Q3: The speeds of two sets of data were 70 (when the flow rate was 2000 veh/hr) and 100 kmftrr (when the (30 marks) flow rate was 1500 veh/hr). Estimate the following: l- The capacity of the highway 2- The average speed of traffic when the flow rate is 1300 veh/hr.
1- Estimating the capacity (Q,,*) of a section By using the fundamental equation of speed-density relationship: u=ur-8t using data set t: 70= r, - (?) ---f,l using dataset2: 100= ur - (?) ---(2) Eq(1)-Eq(2) produces: /28.57u,\ /15u,\ 70_1oo=_(\f/.(r;/ -30=-(T),thenk, =(T,3) Substitute eq(3) in eq(l) produces: / -_ \ To -rr-(w),tr,.n \30l ur = 133.16km/hr and k; = # ki. ur L33.L6 * gmax=i= 60.23 4 =2005veh/hr ---r:l -- 60.23vehlkm 2- Average speed and density at flow rates of 1300 veh/hr. u:106 km/hr at normaltlow condition and u:27,1 at ct