Civil Designer Showcase

Mixed-Use Developments


"With this mixed use development that includes 3500 residential units, we had to look at new roads to be built for access to the site as well as the impact on existing roads."

Talking about his company's involvement in the transport impact assessment and road design for the Buhrein Residential development, Theo La Grange, one of the Directors of EFG Engineers, refers to the two-year process, now complete, that formed part of their appointment to carry out the traffic impact assessment and road design for the lifestyle and security estate with a total capital value of R350 million.

Buhrein Property Development

The scope of the development earmarked for the site located north of the Kraaifontein residential area, includes 3500 residential units, 15 000m of retail GLA, 5000m of mixed use/office GLA, 500m service station GLA, and a school accommodating up to 1200 learners. It is anticipated that the entire development will be completed by 2014, and the first phase by December 2010.

Buhrein Estate
Proposed Road Network Phased Layout (Click to enlarge)

La Grange, a Civil Engineer whose experience includes the design of rural and urban roads, and project management of large provincial road projects, was closely involved with the Traffic Impact Assessment for the Buhrein development, a joint venture partnership with the Charles Potgieter Property Group and the MSP Group who are the developers.

Mixed-Use Development

In line with MSP's strategy to approach each of their projects as a self-sustainable and ring-fenced investment, the Buhrein project is a mixed-use development that encompasses the entire spectrum of development disciplines, including roads and civil infrastructure. Furthermore it represents the trend, both in South Africa and internationally, towards mixed-use development planning.

The reduction in travel time and cost associated with this urban lifestyle where leisure and work opportunities are focused in one location is the primary benefit offered by mixed-use developments. But by no means less important, is the quality and attractiveness of these new urban spaces and the safety and security offered as an extension of the self-contained environment.

The proponents of contemporary mixed-use development promote either a planned community, or suggest multiuse projects (several uses within one or more buildings) in inner core areas. According to a report on the Features, Pitfalls and Comparisons of Mixed Use Project Development with that of Single-Use Projects, authors Cheah and Tan assert: "The name of the game has to be synergy all uses must function smoothly on an independent basis and in conjunction with each other."

They go on to say that "For engineering and construction professionals, the increasing demand for integrated efforts among project team members and frequent emphasis on life cycle planning both add to the necessity to understand the differences between mixed-use and single-use developments."

The reason that mixed-use development is gaining more importance comes down to three primary reasons. The first of these is the increased focus of public policy pointing developers in that direction. Then there is market demand, with indications that more people feel a sense of vibrancy and community when they live in a mixed-use development. And thirdly, the transportation advantage is a huge attraction, with people wanting to use their time more efficiently.

EFG & Traffic Impact Assessment

As with any new development, and more so where commercial and residential opportunities are concentrated in one area, it is critical to look at the impact of traffic on the contiguous roads. As part of the Traffic Impact Assessment for the Buhrein Development, EFG Engineers considered traffic volumes on the Richwood, Okavanago, Mosselbank and Darwin routes comprising the major arteries east of the site.

Buhrein Estate
Buhrein Estate Land Use Plan

In terms of access to the development, EFG proposed three traffic circles along the extension of Darwin Road northwards past the development. According to La Grange this would provide access southwards to Brighton Road and westwards via the extension of New Langerberg Road to Darwin Road.

"Also from our investigation we concluded that the portion of Darwin road from Brighton Road to the last full access to the development, needs to dualled to accommodate the traffic. A single carriageway running past the development has to be built with another link to Okavango Road and an extension to new Langeberg Road."

The TIA concludes that the trip generation of the proposed development is estimated at 3057 (1009 in and 2048 out) and 3395 (2161 in and 1234 out) external trips in the AM and PM peak hour respectively and that approximately 60% of the new Buhrein trips would use Darwin Road southwards toward Brighton Road and 40% would travel westwards along the New Langeberg extension towards Okavango Road.

Taking traffic growth into account over the next few years (with its original 2013 completion date), traffic growth along Brighton Road was calculated based on 3% growth over 5 years.

Traffic along Okavango Road at the Brighton Road intersection was based on a growth rate of 7.8% in the AM peak hour, which makes allowance for the initial phasing of the Garden Cities development to the West of Okavango Road and some growth from the North. The traffic volumes calculated for the AM peak along Okavango were mirrored and used for the PM peak hour.

Civil Designer Software

All the road designs for the project, incorporating the proposed traffic circles, dualling, intersection improvements and extensions were done by EFG's technician Gideon Hahn, whose experience has been in the geometric design of rural and urban roads.

Talking about the application of the software for the Buhrein development, Hahn says, "I used the Survey and Terrain-, Roads- and Turn Modules. The turn module helped with determining the radius for the roundabouts."

Buhrein Estate
Phase 2: Darwin Rd Dual Carriageway (Click to enlarge)

Says Hahn: "The software helps you to make sure you work within the standards set by the project. The Template and Sections Functions help with the calculation of the volumes because a section can be edited with ease. The Modules I personally like are the Survey and Terrain- Roads- and Turn."

EFG Engineers

EFG Engineers provide consultancy services in transportation planning, traffic engineering, infrastructure design, municipal services and construction supervision and are based in Durbanville, Cape Town.

Block I, The Terraces, Steenberg Office Park, 1 Silverwood Close, Tokai 7945.
Tel: +27 +21 701-1850 Fax: +27 +21 701-1822
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