Civil Engineering May 2021 Review Innovations Transportation Engineering
HIGHWAY SAFETY AND ACCIDENT ANALYSIS DESIGN OF PAVEMENT
1. Rigid pavement without dowels
➢ Accident rate for 100 million vehicles per miles of
travel in a segment of a highway: e 3W
t=
f
A(100 ,000 ,000 ) 1m
R=
ADT N 365 L
2. Centrifugal Ratio (CR) or Impact Factor (IF) 2. Rigid pavement with dowels
A = number of accidents during period of analysis 2
v
ADT = average daily traffic CR or IF = 3W at the edge
N = time period in years gR t1 =
L = length of segment in miles
2f
v = design speed of car in m/s 3W at the center
➢ Accident rates per million entering vehicles in an g = 9.81 m/sec2 t2 =
4f
intersection: R = radius of curvature in meters
CR or IF = e + f = F / W
A(1,000 ,000 ) t = thickness of pavement
R= SIGHT DISTANCE W = wheel load
ADT N 365 f = allow tensile stress of concrete
A = number of accidents during period of analysis v2
ADT = the average daily traffic entering the intersection S = vt + 3. Flexible pavement
from all legs 2g ( f G )
N = time period in years W
t = (0.564 ) −r
f1
➢ Severity ratio (S.R.) v=0
wall?
f1 = allowable bearing pressure of subgrade
fatal( f ) + injury(i ) r = radius of circular area of contact between wheel load
SR =
fatal( f ) + injury(i ) + propertydamage(p) vt v2 and pavement
2g( f G ) 4. Thickness of pavement in terms of expansion
braking distance or
DESIGN OF HORIZONTAL CURVE pressure
length of skid mark
1. Min. radius of curvature: expansion pressure
v – running speed in m/s t=
pavement density
v2 t - perception time + brake reaction time
R= f – coefficient of friction between tires and
g (e + f ) pavement
5. Stiffness factor of pavement
G – grade/slope of the road Es
S.F. = 3
deceleration (a) = g (f ± G)
Ep
R = min. radius of curvature
e = superelevation in m/m v Es = modulus of elasticity of subgrade
braking time tb = Ep = modulus of elasticity of pavement
f = coefficient of side friction or skid resistance g (f G )
v = design speed in m/s
g = 9.81 m/sec2 brake efficiency = (f / fave) x 100%
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Civil Engineering May 2021 Review Innovations Transportation Engineering
Definition of Terms: 15. Quaywall or Bulkhead – protection walls for quay DESIGN OF HORIZONTAL CURVE
1. Ports – a harbor with the necessary terminal facilities and wharves for retaining and protecting embankments Problem 2:
to expedite the moving of cargo and passenger at any or retaining fill. A car having a weight of 40 KN is moving at a certain
stage of the journey aside from its wharves, pier and 16. Mooring – a structure where a ship is tied when it is speed around the curve. Assuming no lateral pressure
cargo handling machinery. anchored to enable cargo to be handled in the absence of between the tire and pavement and considering a
2. Harbor – any body of water with sufficient depth for wharves. centrifugal ratio of 0.30.
ships to enter and find shelter in storm and other natural 17. Apron – a space provided in large ports in front of a. Compute the force that will tend to pull the car away
phenomena. berth to facilitate loading and unloading of cargo. from the center of the curve.
3. Natural Harbor – a harbor which is protected by 18. Ocean Port – ports of call for large ships or ocean b. If the degree of curve is 40 determine the maximum
storms and waves by the natural land contours, rocky liners. speed that the car could move around the curve.
outcrops or islands. The entrance to such harbor permits 19. Entry Port – isolated area of ports where foreign c. Compute the angle of embankment to be provided for
navigation. goods are cleared through customs. this speed if the skid resistance is 0.12.
4. Artificial Harbor – a harbor protected by means of 20. Free Port – an isolated and enclosed area within
engineering works on all sides. which goods maybe landed, stored, mixed, repacked, STOPPING SIGHT DISTANCE
5. Commercial Harbor – a harbor in which terminal manufactured and reshipped without payment of duties Problem 3:
facilities are provided. and without intervention of custom officials. A driver traveling at 50mph is 80m from a wall ahead. If
6. Refuge Harbor – a harbor which is used as a haven in 21. Inland Port – ports which are located at the entrance the driver applies the brake immediately at a brake
a storm. of a river. reaction time of 2 seconds and begins slowing the vehicle
7. Wharf – a landing place or the platform built out into 22. Approach Channel – the path or channel in which at 10 m/s2.
or onto the water parallel to the shore for the berthing of ship proceeds from the sea to the harbor. a. Find the distance from the stopping point to the wall.
vessels. 23. Outer Channel – the portion of the channel beyond b. Determine the braking time or time during
8. Jetty – A solid structure which projects into the sea harbor entrance in the open sea. deceleration.
perpendicular to the shore to berth vessels. 24. Inner Channel – the portion lying between the c. Assume that the brake efficiency of the vehicle is 70%,
9. Pier – A platform extending from a shore over water entrance and harbor basin. find the average skid resistance of the pavement.
and supported by piles, used to secure, protect, and 25. Turning Basin – water space which is required for
provide access to ships or boats. maneuvering the ships after they enter the harbor for DESIGN OF PAVEMENT
10. Lighthouse – they are tall tower structures with a going to or leaving a berth. Problem 4:
marine beacon-light camera lantern on top. They are Determine the thickness of pavement from the following
usually erected on points along the shore to guide ships HIGHWAY SAFETY AND ACCIDENT ANALYSIS conditions:
to a nearby port as well as on reefs, shoals or other points a. The pavement is rigid and to carry a maximum wheel
of danger to shipping. Problem 1: load of 60 KN. Neglect effect of dowels.
11. Breakwater – a structure constructed around harbor A 20 km stretch of a highway had the following reported fc’ = 20 MPa and use an allowable tensile stress of
in order to protect the interior water area from the effect accidents: concrete pavement equal to 0.06fc’.
of stormy waves. YEAR FATAL INJURY PROPERTY ADT b. The concrete pavement has an expansion pressure of
12. Revetment – structures used for protecting DAMAGE 0.15 kg/cm2 and a pavement density is 0.0025 kg/cm3.
riverbanks against erosion. c. A 53.5 KN wheel load has a max. tire pressure of 0.62
1991 4 42 110 1000
13. Levee – an embankment built along the side of the MPa. This pressure is to be uniformly distributed over
1992 2 54 210 1200
rivers to prevent the overflow of banks and thus to the area of tire contact on the roadway. Assuming the
1993 5 60 182 1250
protect the adjoining land from flood waters. subgrade pressure is not to exceed 0.14 MPa, determine
1994 7 74 240 1300
14. Dikes or Training Wall – these are employed to direct the required thickness of flexible pavement structure,
1995 6 94 175 1350 according to the principle of the cone pressure
the flow of current in rivers with a view to the
establishment of the more favorable and fixed channel distribution.
a. Find the severity ratio.
and often also to prevent scour and erosion and the
b. Determine the rate of injury accidents.
carrying away of river banks.
c. Compute the rate of total accidents.
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