UNIT 5 Group Project 2

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Unit 5: Group ProjectLecture Note: Supplementary Note 2

Allocated Learning hours: 45

CIVIL ENGINEERING BATCH - 01 (FULL TIME) 3RD SEMESTER

Dr. Lalith Rajapakse/Dr. Lesly Ekanayake

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3.6 External Circulation and Services/Accessibility Features

3.6.1 General Introduction

The access system and general circulation pattern of a

new development will generally be one of the most

critical aspects of its master plan and initially needs to belooked at as a complete entity.

Possible modes of transport to serve the site needs:

Road transport, incl. small-scale electric vehicles

Rail links

Rivers and canals Not often/widely used

Air (for export markets)

Non-vehicular transport (pedestrians)

3.6.2 Road patterns, Entry/Exit Points & Parking

Segregating the in-coming and out-going traffic, usually

by adopting a one-way circulation system

Provision ofa continuous peripheral road system or

"ring road", with the buildings located within the centreof the block

Points to note:

By using minor loop roads or branches, the size of the

area served by the ring road can be increased and

individual facilities can be directly served by the road

system.

A two-way residential frontage road runningparallel to a motorway [USA]

Multi-level access roads: Ring road access toNew Bangkok Swarnabhumi Airport, Thailand.

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3.6 External Circulation and Services

3.6.2 Road Patterns

Points to note Contd.:

Ring road approach enables drivers to search for

parking spaces and to correct mistakes. Hierarchy of roads should be established, reflecting the

different intensity of use of facilities.

Junctions and intersections between different grades of

roads will need to be looked at in detail, particularly in

respect of sight-lines and the spacing between

junctions. Grid road patterns may be used, particularly for large

scale markets, but loop systems are more suitable for

simpler layouts.

Better to avoid any crossroads within the layout and to

make as many of the junctions as possible 3-way (T-

junctions).

The desirable maximum distance from a parking spaceto a utility building should be 100 m; 200 m for peak

parking in overspill areas (maximum 50 m for disabled

parking).

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3.6 External Circulation and Services

3.6.3 Some Useful Key Definitions

Accessibility = f(time, effort, cost, risk, need)

Accessibility is a complex function of the difficulties faced by the user and /her need for the service.

Travel time = f(transport system, distance, frequency of use)

Travel time can be shortened by improving the transport system, that is, the combination of fixed

infrastructure and the carrier using it. It can also be shortened by moving users and services closer

together. The time measure must be considered as an aggregate for all users over time. There is no

point in devoting a lot of resources improving access to a place rarely visited.

Level of service = f(geometry, materials, construction method, robustness)

Levels of service can be improved by better geometry (more width, moderate slopes, gentler curves),

by better materials (smoother and more durable rolling surface), and by the degree of overbuilding (in

that robustness has an impact on the durability over time and interacts heavily with maintenance).

Robustness = f(geometry, materials, methods, traffic, weather, maintenance strategy)

Robustness is a function of how well the road is built in the first place, of the forces acting upon it

(mainly traffic and weather) and the quality of maintenance.

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3.6 External Circulation and Services

3.6.4 Design Considerations/Benefits & Usages

In preparing more detailed proposals for a new development, estimates should be made of the

projected traffic flows and distribution by type of vehicle. These may include:

Delivery vehicles

Retailers' and other buyers' vehicles

Transport for permanent and temporary staff Vehicles of the general public

3.6.5 Design Traffic/Parking Space Requirements

The overall value and appeal of commercial/private buildings and other developments are greatly

dependent upon its accessibility features; i.e. roads and other means of accessibility. However, the

benefits of public roads become largely social and non-monetary in nature. When designing accessroads to a facility, the road engineers and planners need to consider:

Population concerned

Usage (present uses and potential future developments)

Affordability

Alternatives (construction/management/application)

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3.6 External Circulation and Services

3.6.5 Thresholds for Traffic and Transport Impact Assessment (TIA) where National Roads are Affected

VehicleMovements

100 trips in / out combined in the peak hours for the proposeddevelopment

Development traffic exceeds 10% of turning movements at

junctions with and on National Roads.

Development traffic exceeds 5% of turning movements atjunctions with National Roads if location has potential to becomecongested or sensitive.

Size Retail 1,000m2Gross Floor Area.

Leisure facilities including hotels,conference centres and cinemas.

1,000m2Gross Floor Area.

Business 2,500m

2

Gross Floor Area.Industry 5,000m2Gross Floor Area.

Distribution and warehousing 10,000m2Gross FloorArea.

Hospitals and education facilities 2,500m2 Gross Floor Area.

Stadia 1,500 person capacity.

Community Facilities including

places of worship, communitycentres.

1,000m2Gross Floor Area.

Housing 50 dwellings within urbanareas with a populationless than 30,000.

100 dwellings within urbanareas with a populationequal to or greater than30,000.

ParkingProvided 100 on-site parking spaces.

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3.6 External Circulation and Services

3.6.5 Hierarchy of Road Types and Capacities

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3.6 External Circulation and Services

3.6.6 Traffic Analyses and Road Widths/Lanes

Traffic Analysis can be split into two well defined areas:

Traffic Volume Done by Traffic Engineers and does not normally concern the Civil Engineer. This is not

relevant to determining the load on the road, only the size and layout.

Traffic Loading - This is the role of the Pavement Engineer and involves determining the loading on the road tobe carried forward to the Pavement Design.

Traffic Volume

The role of the traffic engineer is to enable all traffic to travel on the road at a reasonable speed and with an

appropriate degree of safety. This is not the loading that is used in the Pavement Design. These values are used

to determine the road width only.

With relation to the volume of traffic using the road, the passenger car is adopted as the standard unit and

other vehicles are assessed in terms of passenger car units (pcu). The classification of vehicles in pcu's is shown

below:

Type of Vehicle Rural Urban

Private cars, motor cycle combinations, taxis and

light private goods vehicles up to 1.5t unladen 1 1

Motorcycles (solo), scooters and mopeds 1 0.75

Goods vehicles over 1.5t unladen weight 3 2

Differences in the urban and rural situations arise due to

the variation of speeds in the two areas. Decisions on road

width are not normally made on total traffic flow per day as

this is misleading but rather on the peak hourly flow.The maximum permissible flow is 3,000 pcu/h for a two

lane dual carriageway and 4,500 pcu/h for a three lane dual

carriageway (motorway). For all purpose roads with

junctions these figures reduce to 1,100 and 1,900 pcu/h

respectively.

Where the road is new, studies must be carried out to

estimate the volume of traffic expected to use the road.

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3.6 External Circulation and Services

3.6.6 Traffic Analyses and Road Widths/Lanes

It is indicated that in normal circumstances a carriageway width of 5.5 m will be required where there is direct access to

dwellings but this can be reduced where there is no direct access. Further information on widths is provided as follows :-

It is indicated that the width of 5.5 m is normally sufficient for cars to maneuver around parked vehicles to use

accesses but where lengths of road do not provide direct access widths can be reduced as follows :-

The need to cater for access by fire appliances is covered and it is necessary to ensure that appliances can reach

within 45 m of a suitable entrance to any dwelling via a road of at least 2.75 m width with 3.66 m being the minimum

necessary to allow for operating space around the vehicle.

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3.6 External Circulation and Services

3.6.6 Road Hierarchy and Recommended Widths

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3.6 External Circulation and Services

3.6.7 Traffic Generation Tables/Guidelines

Average Base Trip Generation during Weekday PM Peak Hour

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3.6.8 Design Details of Car Parking Spaces

Guideline to estimate required number of

parking spaces are given in the table.

All car parking spaces (except disabled spaces)

shall be a minimum of2.4m x 4.8m, with a

minimum aisle width of 6m & 2.0m headroom.

Minimum 18.0m x 5.0m for lorries/trucks.

Should be well lit, incorporate good quality

hard and soft landscaping and be situated in

safe (surveillance by staff or CCTV), accessible

and convenient locations.

Disabled car parking spaces

Disabled car parking spaces shall be aminimum of 3.6m x 4.8m and include a

wheelchair transfer zone of 1.2m.

For adjoining parking spaces, the 2.4m x 4.8m

minimum is acceptable when combined with a

common 1.2m transfer zone.

For in-line spaces the minimum shall be 6.6m x

2.4m with access available from one side.Parking spaces and transfer zones should be

clearly marked with the British Standard

Disabled symbol on the road surface and a

notice at the drivers eye level; BS3262 Part 1.

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3.6.8 Design Details of Car Parking Spaces Operational Spaces

Parking Spaces for Disabled Persons

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3.6 External Circulation and Services

3.6.9 Design Details for Service Spaces for People with Disabilities

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3.6 External Circulation and Services

3.6.9 Design Details for Service Spaces for People with Disabilities

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3.6 External Circulation and Services

3.6.10 Related BS/BS EN Codes of Practice

BS 8300:2009 Design of

buildings and their approaches

to meet the needs of disabled

people. Code of practiceBS 8300 explains how the built

environment can be designed to

anticipate, and overcome,

restrictions that prevent disabled

people making full use of premises

and their surroundings.

A few British Standards are receiving

updates to keep up with what is

happening in the industry, but many

"BS EN" standards are now current,

with others imminent to replace

current popular standards.

An example of a recent important

update is BS 594 and BS 4987 being

superseded by the BS EN 13108 family

of specifications and a new British

Standard BS 594987, from 1st.January

2008.

BS 7533-1 : 2001 : Pavements constructed with clay, natural stone, or concrete pavers -Part 1 : Guide for the structural design of heavy duty pavements constructed of clay paversor precast concrete paving blocks

BS 7533-2 : 2001 : Pavements constructed with clay, natural stone, or concrete pavers -

Part 2 : Guide for t he structural design of lightly trafficked pavements constructed of claypavers or precast concrete paving blocks BS 7533-3 : 2005 : Pavements constructed with clay, natural stone or concrete pavers -Part 3 : Code of practice for laying precast concrete paving blocks and clay pavers forflexible pavements

This part of the standard gives recommendations for the laying of conventional andpermeable pavements using concrete paving blocks conforming to BS EN 1338 and claypavers conforming to BS EN 1344.This document is intended for flexible pavements for roads, industrial areas and other paved

surfaces subjected to all categories of static and vehicular loading and pedestrian traffic.The principles given apply to all shapes and sizes of paving units cover ed by BS EN 1338and BS EN 1344. BS 7533-4 : 2002 : Pavements constructed with clay, natural stone, or concrete pavers -Part 4 : Code of practice for the construction of pavements with precast concrete flags ornatural stone slabs. BS 7533-7 : 2002 : Pavements constructed with clay, natural stone, or concrete pavers -Part 7 : Code of Practice for the construction of pavements of natural stone setts andcobbles

This part of BS 7533 gives recommendations for the laying of natural stone setts a ndcobbles intended for pavements, roads, industrial areas and other paved surfaces subjectedto all categories of static and vehicular loading and pedestrian traffic. BS 7533-10 : 2004 : Pavements constructed with clay, natural stone or concrete pavers -Part 10 : Guide for the structural design of trafficked pavements constructed of natural stonesets.

This part of the standard provides guidance on the design of pavements surfac ed withnatural stone setts manufactured in accordance with BS EN 1342 and laid in accordancewith BS 7533-7.It applies to all pavements including those subjected to commercial vehicular traffic, e.g.

delivery vehicles.