highway engineering 1 test

The road, or road reserve, is defined as the area from the property boundary on one side of the road to the property boundary on the other side of the road. This includes the berm (grass verge), footpath and carriageway

the road is defined as the area from the boundary of the property on one side, the grass, footpath, berm, kerb and drain, carraigeway, other kerb and drain, berm, footpath and grass up to the property bounday

A road that mainly carries through traffic from one region to another

forms principal avenues of communication for traffic movements

Encourage roadside development and access that is compatible with the arterial function (i.e not residential more semi-commercial)

Access should be prioritized versus access function

Major regional and inter-regional movement High speed Efficient and safe movement of vehicles

using ramps, variable sign messages, speed controls, lane management and travel time estimation

Collects and distribute traffic, incl buses, within residential, commercial and industrial areas. -

Provide a link for local streets to main arterials. - Need to manage residential pressures to reduce speed overriding the need for traffic movement functions

Provide vehicle access to developments and residential properties Access for emergency and service vehicles

Pedestrian and cyclist movements Neighbourhood social interactions Aesthetic values to the neighbourhood Speed is to be kept low i.e. 50km hr-1 or less

Keep grades and curvature to the minimum necessary to satisfy the service requirements of the highway.

Never have two roads intersecting near a bend or at the top or bottom of a hill

Always provide adequate sight distance and avoid sudden changes in sight distance, especially near intersections.

Avoid areas or objects of historical, recreational or cultural significance.

Avoid having a sharp horizontal curve on or adjacent to a pronounced vertical curve.

Locate the highway wherever possible along property boundaries not through the middle of blocks of land particularly in farming areas.

Where it is practical maximise use of existing highway alignment to reduce land purchase costs.

All of the above

Empirical: Based on experiments and experience, can be simple or complex, charts etc.

Mechanistic-Empirical: Using stresses, strain and deflections caused by loading and material properties on the pavement structure.

9.6.1 Any portion of the ground whose slope is steeper than three horizontal to one (1V/3H) vertical shall be benched before filling is placed on it, unless otherwise directed by the Engineer.

9.6.2 Each bench shall be constructed to a width adequate to permit suitable construction equipment to operate on it. The base of the benches shall be sloped inwards at a slope of 12 horizontal to 1 vertical (1V/12H). The longitudinal profile of each bench shall be graded to ensure adequate drainage and safe discharge of water.

"Borrow" is excavation from outside the construction batter limits shown on the drawings.

"Overbreak" is the excavated material removed by the Contractor's operations from outside the construction cut batter limits shown on the drawings, but not authorised as borrow.

"Surface Water Channel" is a water channel formed at the subgrade surface at the edge of the road. (1 mark each)

Type A Material is all material which does not fall within categories R1, R2, W, or U.

Type R2 Material This is rock which cannot be productively ripped unless equipment is used which is more powerful than a crawler tractor having net engine (or flywheel) power in the range 270310 kW and fitted with a single shanked hydraulic ripper. If a tractor meeting the above specification is not readily available then, a 30 tonne hydraulic excavator with a single ripper on the boom may be used to determine R2 materials, providing the performance of the hydraulic excavator has been compared with a crawler tractor in similar materials.

Type R1 Material This is rock which cannot be productively ripped unless equipment is used which is more powerful than a crawler tractor having net engine (or flywheel) power in the range 100115 kW and fitted with a twin shanked hydraulic ripper. If a tractor meeting the above specification is not readily available then, a 30 tonne hydraulic excavator using a bucket may be used to determine R1 materials. Alternatively, a smaller excavator with a single tyne ripper may be used providing its performance has been compared with a crawler tractor in similar materials.

Chip encased in binder

First coat seals Grade 4 chip lower viscosity bitumen

Second coat seals– Grade 2 or 3 chip with180/200 bitumen

Strength and Hardness Aggregate shape Durability or Soundness Strength & Hardness The aggregates at top layers - Stress action due to traffic wheel load, - Wear and tear, - Crushing. Aggregates should possess high resistance to crushing, and withstand the stresses due to traffic wheel load. The surface aggregates are subjected to constant rubbing or abrasion due to moving traffic especially steel tyred vehicles. Should be hard enough to resist the abrasive action caused by the movements of traffic.

Shape of aggregates Aggregates which happen to fall in a particular size range may have rounded, cubical, angular, flaky or elongated particles. Flaky and elongated particles have less strength and durability when compared with cubical, angular or rounded particles of the same aggregate. Avoid too flaky and too much elongated aggregates.

Durability The property of aggregates to withstand adverse action of weather is called soundness. Aggregates are subjected to the physical and chemical action of rain and bottom water, impurities there-in and that of atmosphere. It is desirable that the road aggregates used in the construction should be sound enough to withstand the weathering action

The sand equivalent shall not be less than 40 when the aggregate is tested according to NZS 4407: 1991, Test 3.6 Sand Equivalent Test. (1 mark)

The clay index of the fraction of basecourse passing the 75μm sieve shall not be greater than 3 when the aggregate is tested according to NZS 4407: 1991, Test 3.5 Clay Index Test.

The plasticity index of the fraction of basecourse passing the 425μm sieve shall not be greater than 5 when the aggregate is tested according to NZS 4407: 1991, Test 3.4 Plasticity Index Test.

Bitumen is black, pitch-like materials obtained from refining crude petroleum which originated as organic deposits in the earth’s crust.

In the US bitumen is referred to as asphalt and occasionally as asphaltic bitumen or asphaltic cement.

Fluxing the permanent reduction in the viscosity of a cut back bitumen, normally using AGO

Cutting back is the temporary reduction in the viscosity of cut back bitumen, normally using kerosene

All of the above

Polymer Modified Bitumen (PMB) This is a penetration grade binder with an addition of a polymeric substance , often latex , to give greater flexibility and ductility particularly at lower road surface temperatures.

Rubber and Polymer-modified Binders Scrap rubber, new rubber and polymer additives in various forms may be used in sprayed sealed work to modify bituminous binders in order to (i) improve aggregate retention, (ii) reduce the temperature susceptibility of the binder, and (iii) alleviate or reduce reflection cracking. (2 marks for PMB and 3 for the objectives)

Traffic Volumes and Composition

Design Speed

Design Vehicle

Environment

Access – safe , efficient

Drainage – runoff disposal, flooding • Utility services

all of the above