BCE Highway 5 — Questions and Answers
Question 1: In highway drainage design, the rational method formula Q = CiA is used to estimate peak runoff. What does the variable 'i' represent?
- Infiltration rate in in/hr
- Rainfall intensity in in/hr for the design storm duration (Correct answer)
- Imperviousness coefficient
- Inlet interception efficiency
Correct answer: Rainfall intensity in in/hr for the design storm duration
In Q = CiA, 'i' is the rainfall intensity (in/hr) corresponding to the time of concentration and return period from IDF curves.
Question 2: What is the purpose of a truck climbing lane on a steep uphill grade?
- Provide an emergency runaway truck escape route
- Allow slow-moving trucks to separate from faster passenger vehicles (Correct answer)
- Reduce pavement thickness requirements
- Increase highway capacity by adding a passing zone
Correct answer: Allow slow-moving trucks to separate from faster passenger vehicles
Climbing lanes give slow trucks an auxiliary lane so that passenger vehicles can maintain speed, preventing capacity reduction on steep upgrades.
Question 3: Which AASHTO functional classification serves the highest traffic volumes and longest trip lengths in the US highway system?
- Local roads
- Collectors
- Minor arterials
- Principal arterials (Interstates) (Correct answer)
Correct answer: Principal arterials (Interstates)
Principal arterials, especially the Interstate system, are at the top of the functional classification hierarchy, designed for maximum mobility and long-distance travel.
Question 4: What pavement design concept does 'resilient modulus' (Mr) represent for subgrade soils?
- Permanent deformation under static loading
- Elastic stiffness of soil under repeated dynamic loading (Correct answer)
- Shear strength at failure
- Consolidation settlement potential
Correct answer: Elastic stiffness of soil under repeated dynamic loading
Resilient modulus measures the elastic (recoverable) stiffness of soil under repeated cyclic loads simulating traffic, and is the key subgrade input in mechanistic-empirical pavement design.
Question 5: In a signalized intersection, what is the 'lost time' per phase primarily associated with?
- Yellow and all-red clearance intervals only
- Start-up delay at the beginning plus clearance delay at the end of green (Correct answer)
- Total red interval duration
- Pedestrian crossing time
Correct answer: Start-up delay at the beginning plus clearance delay at the end of green
Lost time consists of start-up lost time (sluggish queue discharge at green) plus clearance lost time (unused green during yellow/red), totaling typically 3–4 seconds per phase.
Question 6: Which horizontal alignment element connects two tangents with deflection angle Δ and has a mid-ordinate distance M from chord to curve?
- Spiral curve
- Simple circular curve (Correct answer)
- Compound curve
- Reverse curve
Correct answer: Simple circular curve
A simple circular curve of radius R connects two tangents; the mid-ordinate M = R(1 − cos Δ/2) is used in sight distance calculations around the curve.
Question 7: What is the primary environmental concern addressed by including a sediment basin in a highway construction stormwater pollution prevention plan (SWPPP)?
- Reducing vehicle exhaust emissions during construction
- Capturing disturbed soil particles before runoff leaves the site (Correct answer)
- Controlling noise from heavy equipment
- Preventing fuel spills into groundwater
Correct answer: Capturing disturbed soil particles before runoff leaves the site
Sediment basins detain stormwater long enough for suspended soil particles disturbed by grading to settle out before the water is discharged off-site.
BCE Highway 5
In highway drainage design, the rational method formula Q = CiA is used to estimate peak runoff.
What does the variable 'i' represent?