Roads and Stormwater Division

THE CITY OF TSHWANE

ROADS AND STORMWATER DIVISION

MINIMUM STANDARDS APPLICABLE TO

ROAD CONSTRUCTION AND STORMWATER DRAINAGE SYSTEMS

15 September 2008

Q:\Roads & Stormwater\Infrastructure Provision\MASTER DOCS\CD's for Consultants\CD for Consultants_September 2008_under construction\1_Design\MINIMUM STANDARDS.doc

CITY OF TSHWANE

ROADS AND STORMWATER DIVISION

MINIMUM STANDARDS APPLICABLE TO ROAD CONSTRUCTION AND STORMWATER DRAINAGE SYSTEMS

The standards for road construction and stormwater drainage systems will be according to the Guidelines for the provision of engineering services in residential areas (the so-called Red Book), published by the Department of Housing, unless stated otherwise here.

1. RESERVE AND STREET WIDTHS

According to standard drawing PLN 001, sheets 1 to 4, of this Division.

2. DESIGN STORMWATER RECURRENCE INTERVAL FOR THE DESIGN OF THE STORMWATER SYSTEM

2.1 Minor System

The minor system comprises catchpits, junction boxes, manholes, inlet structures, canal pipes and box culverts necessary to drain stormwater of regular storms.

A design storm with a 1-in-2-years recurrence interval is used as the design standard.

2.2 Major System

The major system comprises elements of the minor system, the road surface itself, pipes, box culverts, canals, natural low points, spruits, rivers and flood-attenuation structures necessary to drain stormwater of larger storms without damage and loss of life.

A design storm with a 1-in-50 years recurrence interval is used as the design standard, but in such a way that -

(i) the section of the major system comprising roads and enlarged stormwater drainage systems in combination with the minor system, up to a natural waterway or low point be designed for a post development run-off with a 1-in-20 years recurrence interval;

Q:\Roads & Stormwater\Infrastructure Provision\MASTER DOCS\CD's for Consultants\CD for Consultants_September 2008_under construction\1_Design\MINIMUM STANDARDS.doc

(ii) the major system, where it consists of a natural or canalised waterway or low point, be designed for a 1-in-50 years recurrence interval to convey a post-development run-off without flooding any building.

3. MINIMUM PIPE SIZES

Stormwater pipes must have a minimum diameter of 450mm to prevent blockages and make cleaning easier.

4. MINIMUM GRADIENTS

The minimum longitudinal gradient of roads, pipes, box culverts and canals must be 1:150 (0,667%) owing to practicability during construction and problems with sedimentation, as well as to prevent lower-lying erven from being flooded.

The cross-fall of streets must be a minimum of 2%.

5. MAXIMUM GRADIENTS

5.1The following is the maximum gradient for roads:

Class 4 roads (local distributors) / 1:10 (10%) for a maximum length of 100m
Class 5a roads (residential collector road) / 1:8 (12,5%) for a maximum length of 70m
Class 5b to 5d roads (residential access roads) / 1:5 (20%) for a maximum length of 50m

5.2The maximum gradient for steep roads joining a crossroad is 6% for a distance of at least 20m.

5.3Each erf MUST have access at 1:5 (20%).

5.4The maximum cross gradient of sidewalks, excluding the erf access, is 1:3.

5.5The maximum slope of sides of a trapezoidal canal is 1 in 4.

6. FLOW VELOCITIES

The minimum flow velocity allowed in aclosed stormwater conduit is 1m/s.

The maximum flow velocity allowedin open channel flow is 3.5m/s

Q:\Roads & Stormwater\Infrastructure Provision\MASTER DOCS\CD's for Consultants\CD for Consultants_September 2008_under construction\1_Design\MINIMUM STANDARDS.doc

7. KERBING

The following types of kerbing must be used as indicated in Table A to prevent edge weathering of streets, as well as erosion and wearing away of the road surface and sidewalks:

(i) 300 sloping kerb

(ii) 400 sloping kerb

(iii) 500 sloping kerb

(iv) Semi-vertical kerb with channel

(v) Edge beam

8. SURFACING FOR STREETS

All streets must be provided with surfacing equal to at least a single seal to protect the road surface, which serves as a drainage canal for the major system according to the stormwater management approach, against erosion and wearing away and to prevent the penetration of moisture into the pavement layers.

9. DETAIL AND DOCUMENTATION

The following documentation must be used for tender and construction purposes:

9.1General Conditions of Contract for the Construction of Civil Engineering Works –First Edition (2004).

9.2Standard Specifications for Municipal Civil Engineering Works - Third Edition (2005).

Detail of catchpits, junction boxes, manholes, etc must be according to the Division’s standard detail drawings.

The construction drawings should be at least in an A2 format and must contain the standard Roads and Stormwater Division’s title block.

The standard title block can be obtained in electronic format from the Roads and Stormwater Division. Please send your request to

Q:\Roads & Stormwater\Infrastructure Provision\MASTER DOCS\CD's for Consultants\CD for Consultants_September 2008_under construction\1_Design\MINIMUM STANDARDS.doc

TABLE A: KERBS TO BE USED FOR ROAD CONSTRUCTION IN TSHWANE

APPLICATION / TYPE OF KERB
300 Sloping Kerb / 400 Sloping Kerb / 500 Sloping Kerb / Edge Beam / Semi-vertical Kerb
(fig. 7) with channel / Barrier Kerb (fig. 3) with channel
Roads up to 5m wide / Straights and curves / ⃝ / ⃝
(See Note 1)
Bellmouths / ⃝
Roads wider than 5m and up to 6m wide / Straights and curves / ⃝ / ⃝
(See Note 1)
Bellmouths / ⃝
Roads wider than 6m / Straights and curves / ⃝
Bellmouths / ⃝
Bus and taxi bays / ⃝
Where vehicles crossing the kerb is discouraged / ⃝
Where vehicles crossing the kerb is prohibited / ⃝
Joint between asphalt and block paving / ⃝
Temporally edge restraint in asphalt paving to be removed when road is extended. / ⃝
NOTES:
(1)An edge beam shall be constructed on the high side of roads with a single cross-fall.
(2)At the intersection or roads with different road widths, the bellmouths shall be constructed with kerbs prescribed for the bellmouths of the wider road.

Q:\Roads & Stormwater\Infrastructure Provision\MASTER DOCS\CD's for Consultants\CD for Consultants_September 2008_under construction\1_Design\MINIMUM STANDARDS.doc