Transpo. Summary

8/2/2019 Transpo. Summary

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Western Mindanao State University

Normal Road, Baliwasan, Zamboanga City

College of Engineering and Technology

INTERSECTIONS, INTERCHANGES, TERMINALS

SUBMITTED BY:

Marynhol C. Solis

(BS SE IV-A)

SUBMITTED TO:

Engr. Abdulkarib M. Kaddu

(CE148 Instructor)


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INTERSECTIONS, INTERCHANGES, TERMINALS

A.) INTERSECTIONS AT GRADE, GRADE SEPARATIONS AND INTERCHANGES(1.)Intersections at Grade

- Most highways intersect at grade, and the intersection area should be designed to provideadequately for turning and crossing movements, with due consideration given to sight

distance, signs, grades and alignment.

- Simple intersections at grade consist of a junction of three, four, or more roadapproaches.

- It is frequently assumed that all turning movements of intersections are accomplished atspeeds of less than 32 km/h (20 mph).

(2.)Islands and channels- Traffic islands or pavement markings may be used at intersections to facilitate the safe

and orderly flow of vehicles and pedestrians.

- Purposes of islands in an intersection:a.) Separation of conflictsb.) Control of angle of conflictc.) Reduction of excessive pavement areasd.) Regulation of traffic flow in the intersection areae.) Arrangements to favor a predominant turning movementf.) Protection of pedestriansg.) Protection and storage of turning and crossing vehiclesh.) Location of traffic control devices

- 3 major classes of islands:a.) Directional islandsb.) Divisional islandsc.) Refuge islands

(3.)Rotary Intersections- A rotary intersection is one in which all traffic merges into and emerges from a one-way

road around a central island.

- Advantages of a rotary intersection:a.) Traffic moves continuously from all legs and reduced speed at periods of low volume.b.) Because crossing movements are eliminated, accidents are likely to be less serious.c.) Where more than four intersection legs are involved, the design layout may be

simplifies.

d.) The cost of an at-grade intersection may be considerably less than that of gradeseparation structures.

- Disadvantages of a rotary intersection:a.) A rotary can handle no more traffic than an adequately designed channelized layout.b.) It has been found that unsatisfactory functioning occurs when two or more legs

approach design capacity.

c.) The area involved to satisfy proper geometric design of a rotary is extensive.d.) Channelization will often prove more acceptable if large pedestrian traffic is expected.e.) Most rotaries are designed to function at low speeds.f.) For proper functioning, it has been found that adequate lighting must be provided and

access controlled on the intersecting legs.


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(4.)Grade separations and Interchanges- Grade separations and interchanges may be warranted:

a.) As part of an express highway system designed to carry volumes of traffic.b.) To eliminate bottlenecksc.) To prevent accidentsd.) Where the topography is such that other types of design are not feasiblee.)

Where the volumes to be catered for would require the design of an intersection atgrade of unreasonable size.

f.) Where the road user benefit of reducing delays at an at grade intersection exceedsthe cost of the improvement.

- Four main types of interchanges and ramp layouts:a.) T and Y interchangesb.) Diamond interchanges (e.i. SPUI)c.) Partial and full cloverleafs

Disadvantages: The layout requires large land areas Declaring traffic wishing to leave the through lanes must weave with

accelerating traffic entering the through lanes.

d.) Directional interchanges(5.)Design of Ramps and Turning Roadways

- A turning roadway is a connecting roadway for traffic turning between two legs of anintersection. The term ramp is used to refer for all types of turning roadways that connect

two or more legs at an interchange. AAS1170 recommends friction factors of 0.32, 0.23,

and 0.18 for design speeds of 24, 40and 56 km/hr (15, 25, and 35 mph), respectively.

(6.)Railroad Grade Intersections- All railroad intersections at grade require proper advance warning signs. Recommended

standards for railroad-highway grade-crossing protection have been adopted by the

Association of American Railroads. Railroad grade-separation structures may consist of an

overpass on which the highway is carried over the railroad or an underpass that carries

the highway under the railroad.

B.)DESIGN OF PARKING FACILITIES(1.)Location of Off-Street Parking Facilities

- Parking lots and garages should be located on or near major arterials; garages should haveaccess to two or more streets. It is also desirable that both lots and garages be accessed

by right-hand turning movements.

(2.)Lay-out of Parking Lots and Garages- A parking lot or garage should be rectangular with cars parked on both sides of access

aisles. Parking sites should be wide enough to provide two or more bays approximately

18m (60 ft) wide. Relatively long aisles preferably 76 m (250 ft) or longer, function well.

90 parking is generally used for two-way traffic. If space permits, it is desirable to provide

pedestrian sidewalks between adjacent lines of parking cars. Parking layout dimensions

for 9 by 18.5 ft. stalls arranged at various angles.

- The best parking layout for a given site, usually determined by a process of trial willdepend primarily on these characteristics.

The size and shape of the available area Type of facility (attendant, self-park) Type of parker (especially long-term versus short-term)


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Type of operation(pull-in, bade-in, one-way, two-way)(3.)Parking Garage Design Criteria

- Single entrances an exits, with multiple lanes, are preferable to several openings.Entrances and exits should be located away from street intersections to prevent

congestion on the street. Lane widths of 3.6 to 4.3 m (12-14 ft.) are typically used for

entrances and exits. Counter-clockwise circulations are preferred for parking garages.

(4.)Curb Parking- 3 basic types of curb stalls are used:

a.) End stalls (typically 6.1 m(20 ft.) in length.b.) Interior stalls (usually 6.7 m(22 ft.) long providing approximately 1.4 m(4.5 ft.)

between adjacent cars for maneuvering).

c.) Paired parking stalls (consists of pairs of contagious 5.5 m(18 ft.) stall separated by a2.4 m (8 ft.) open space that may be used for maneuvering).

C.)TRUCK TERMINAL PLANNING AND DESIGN- The planning and design of facilities to accommodate the loading, unloading,. And parking

of trucks can have a significant impact on the operational efficiency of the sheet and

highway system.

(1.)Truck Terminal Planning Involves the determination of the overall size and general layout of facilities

required to handle the forecast quantity of freight. This includes estimating the

number of loading berths as well as the amount of space required for the handling

and temporary storage of the freight.

(2.)Truck Terminal Design Criteria To allow proper clearances on each side of 2.6 m (8.5 ft.) wide vehicles, a

minimum width of 3.4 m(11 ft.), and preferably 3.6 m (12 ft.) is recommended for

each spot.

The dock approach should be at least twice the length of the longest tractor-trailer combination. If 3.4 m(11 ft.) widths are used for dock spots, the apron

length should be increased. The dock height should be as close as possible to the

bed height of the vehicles using the dock. Vertical clearance of at least 4.6 m(15

ft.) should be provided to accommodate the 4.1 m (13.5 ft.) high trailer.

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