It was safe It was economical It worked (in the sense that it met all the specified operating requirements).

Sample Answer IRSE Exam, Module 2 (Main Line Practice), 2017 Examiners Overall Comments: By submitting a well signalled and reasonably compliant solution, this candidate was awarded high marks in the 2017 Module 2 (Main Line) section of the IRSE Examination. The solution offered satisfied the three basic requirements of any layout: It was safe It was economical It worked (in the sense that it met all the specified operating requirements). Question 1 a) Determine the minimum braking distances for passenger trains and freight trains using the characteristics specified on layout 1. From your calculations, determine the minimum signal spacing. [5 marks] Speed (km/h) Speed (m/s) SBD (v 2 / 2a) SBD Freight Passenger 200 55.5 1930m - 180 50 1565m - 100 27.7 485m 775m 90 25 395m 625m On main line min spacing is 1930m Appropriate signalling braking distances were correctly calculated. 2017 Exam Module 2 Sample Answer MainLine.docx 1

b) Determine the best theoretical headway for both 3 and 4 aspect signalling between B and E at uniform minimum signal spacing and a non-stop passenger train at a speed of 180 km/h. Explain how the results of these headway calculations determine your choice of signalling system. [5 marks] 3 aspect H P = R + 2 SBD + OL + L R: reading distance 10 sec @ 180 km/h = 500m H P = 500 + 2 1930 + 180 + 200 H P = 4740 H T = H D V = 4740 ~ 95 sec 50 4 aspect H T = H D V = R + 1.5 SBD + OL + L = 3775 50 ~ 76 sec Mainline 4-5 tph + up to 7 to branch. Aim 200 sec non-stop headway. 3 aspect can achieve but stopping and diverting around C means I think 4 aspect appropriate here, 3 aspect D-E, 2 aspect for A-D. 4 aspect mainline 965 1445m post-post ignoring 2/3 rule. 645 1930 absolute post-post. Minimum headways were determined for both three and four aspect signalling using the correct values for the maximum permissible and timetabled speeds Three aspect signalling was nominated for the traffic level specified but it was recognised by reference to layout 1 that flexibility would be improved by providing four aspects on the main lines between B and D. There is an incorrect reference to two aspect signalling between A and D - two aspect (red/green) signalling is normally confined to metros. 2017 Exam Module 2 Sample Answer MainLine.docx 2

c) The branch to station H experiences heavy passenger flows in connection with sporting events at H. State what is the limiting factor in the number of trains that can traverse the branch. Determine graphically, or by calculation, the maximum theoretical capacity of the branch in trains per hour. All trains traverse the branch at an average speed of 90km/h. State all assumptions. [10 marks] The single line tunnel is limiting factor. 25ms -1 Assume one train in one direction then one in other Assume 180m overlap clear of points. Assume train is stationary ready to enter tunnel when opposing train leaves tunnel. Acc 0 to 25ms -1 v = s t v = u + at t = v a = 25 = 31.25 sec 0.8 s = v mean t = 25 2 31.25 = 390.6m Constant speed Distance = 25 + 180 + 5500 390.6 + 200 = 5514.4m Time = s v = 5514.4 25 = 220.6 sec 2017 Exam Module 2 Sample Answer MainLine.docx 3

Total time one train = Driver reaction 5 s Acc Constant 31.25 sec 220.6 sec (+ TC / interlocking reaction time ignored) 257 sec Same for other direction So between two trains same direction 2 = 514 sec = 0.1427 hours 1 7tph The presence of the long tunnel at V was correctly identified as the factor limiting the headway between C and H; the calculation gave a maximum throughput of seven trains per hour. The candidate obtained full marks for this question. 2017 Exam Module 2 Sample Answer MainLine.docx 4

Question 2 Signal layout 1 in accordance with the notes thereon, numbering the signals (or equivalent) and defining all routes. [60 marks] See layout 2017 Exam Module 2 MainlineLayout.pdf Route Aspect Exit Note 7A(M) M 13 Auto 7B(M) M + Pos4 23 MAR 32A(M) M 28 32B(S) PL Branch siding - 105A(M) M 11 105B(M) M + Pos4 13 MAR The freight terminal at A was economically signalled using hand points - adequate for the traffic level specified. A feature missed by many candidates was the requirement for an up starting signal (101) located a train length in advance of the connection to Siding 1, otherwise shunting into this siding would have to occupy the single line block section. Signal 101 doesn't need an overlap (there is no signal reading up to it) but the associated stop board should have had one. Signal 5 on the Down Main should be a controlled signal - there is a swinging overlap in advance of signal 7. The numbering of signals on the Up Main is incomplete - the candidate noted running out of time. On the Up Branch, the provision of signal 24 and its associated distant enabled a following train from H to enter the tunnel at the earliest opportunity. Also, a running shunt at G enabled an engineering train to run round. Both these features were omitted by many candidates. Route boxes were provided for only a few signals. 2017 Exam Module 2 Sample Answer MainLine.docx 5

Question 3 Number all power worked points and indicate their normal position. Add any trap points necessary. Identify hand worked or ground operated points as such. [10 marks] See layout 2017 Exam Module 2 MainlineLayout.pdf All points were numbered, normal lies correctly shown where necessary and trapping protection shown in the correct places. The candidate obtained full marks for this question Question 4 Mark the limits of all train detection equipment and identify each in sequence. [10 marks] See layout 2017 Exam Module 2 MainlineLayout.pdf Good use was made of axle counters for the long block sections between A and C and between C 2017 Exam Module 2 Sample Answer MainLine.docx 6