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16-Civ-B10 Traffic Engineering: May 2015

Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)

  1. Question 1 Signalised Four-Legged Intersection — Arrival Flow, Saturation Flow, Clearance Intervals and Flow Ratio
  2. Question 2 Parking-Space Availability and a Toll-Booth Queue
  3. Question 3 Freeway Service Flow Rate at Level of Service C, and the Greenshields Flow–Density Curve
  4. Question 4 Deterministic Queueing at an Incident Bottleneck
  5. Question 5 Moving-Vehicle Method for Volume and Travel Time
  6. Question 6 Service Volumes on an Urban Freeway and Level of Service on a Rural Two-Lane Highway
  7. Question 7 Peak Hour Factor from Interval Counts, and Spot-Speed Statistics

Start with Question 1 →

Paper format. 98-Civ-B10 Traffic Engineering, National Examinations, May 2015. Three-hour duration, OPEN BOOK, any non-communicating calculator permitted. Seven questions, all of equal value (20 marks each) with the mark split printed in the grading scheme; the paper requires a total of five solutions. All seven are worked below, because this document is a study resource rather than an exam script.

Reference texts. Garber, N. J. and Hoel, L. A., Traffic and Highway Engineering — Ch. 4 (traffic-engineering studies: volume counts, peak-hour factor, spot-speed studies), Ch. 6 (fundamental principles of traffic flow: the Greenshields model, deterministic and stochastic queueing, the moving-observer method) and Ch. 8 (intersection control: saturation flow, change and clearance intervals). Transportation Research Board, Highway Capacity Manual — basic-freeway-segment and two-lane-highway level-of-service criteria and the lane-width, lateral-clearance and heavy-vehicle adjustment factors. Transportation Association of Canada, Geometric Design Guide for Canadian Roads and the Manual of Uniform Traffic Control Devices for Canada — Canadian lane widths, crosswalk practice and clearance-interval policy. Institute of Transportation Engineers, Traffic Engineering Handbook — queueing applied to parking and toll facilities.

Check — declared assumptions, invoked under the paper’s own NOTE 1 and NOTE 2 (“any data required, but not given, can be assumed”, with a clear statement of the assumption). This paper is open-book and deliberately withholds several standard table values. The following are used consistently throughout and each is restated where it is first applied:

  • Bus (heavy-vehicle) passenger-car equivalent on the level intersection approaches of Question 1: EB = 2.0.
  • Two-phase signal operation at the Question 1 intersection (one phase for the north–south pair, one for the east–west pair), with no start-up lost time given, so the whole intergreen is taken as lost time.
  • Maximum service flow rates and volume-to-capacity ratios for basic freeway segments at a 100 km/h design speed: 700/1000/1450/1800/2000 pc/h/lane is the 110 km/h family, so the 100 km/h family 600/1000/1450/1800/2000 pc/h/lane (v/c = 0.30/0.50/0.72/0.90/1.00) is used, with an ideal capacity of 2000 pc/h/lane.
  • Two-lane-highway ideal capacity 2800 pc/h both directions, with level-terrain v/c ratios 0.15/0.27/0.43/0.64/1.00 at 0 % no-passing zones, and a 50/50 directional split (fd = 1.00).
  • Passenger-car equivalents on specific grades: ET = 5 for trucks on both the 4 % / 1.0 km grade and the 3 % / 1.5 km grade, ER = 3 for recreational vehicles on the 4 % grade, EB = 1.6 for intercity buses on grades of 4 % or flatter, and ET = 2 for trucks in general level terrain.

Different editions of the capacity manual tabulate these cells slightly differently. Where an alternative reading changes an answer materially, the alternative is computed and stated alongside; the method and the arithmetic are what carry the marks.