Streamlining Transport for London’s development appraisal process through digital innovation.

Transport for London, one of London’s largest landowners and a local governing body, prioritised the redevelopment of its existing land portfolio to unlock new housing opportunities within the capital. TfL wanted to develop an automated cost solution that would allow them to speed up their appraisal process to make quick, informed decisions at scale.

Key information

Location: London, UK

Date started: 2019

Completion date: 2021

Client type: Infrastructure

Key services: Cost management

Automated cost model

Utilising outputs from a land mass-modelling software, we were tasked with evaluating and prioritising multiple design options for more than 2,000 sites earmarked for residential development, with a short timeframe of three months to deliver the project.

Traditionally at this stage of design, we would carry out a simple area-based assessment centred around an industry standard cost structure, such as the New Rules of Measurement 1. Given the client’s requirements it was clear that an automated solution would be required.

Digital innovation

We needed to create a custom cost model which could be integrated into a digital platform, generating reliable, automated cost estimates based on datasets produced by the mass-modelling software. We chose a parametric-based cost model and made this bespoke to TfL, as this allowed us to integrate functions for variable outputs received by the mass-model, set rules for a generic cost base and build-in algorithms for any errors returned (where datasets could not be generated) and/or abnormal site conditions. Using this custom model ensured that we could achieve a greater degree of cost accuracy.

Due to the nature of the land-use, many sites had known risk items and abnormal conditions that the client wanted factored into the estimates. The user dashboard would be comparing capital costs against the sales value for the area so needed to reflect a realistic assessment to ensure profitable massing options would be prioritised accordingly.

To guarantee the above did not over-state the build costs (and skew the prioritisation), we ran a series of live tests with the client, using different sample types to demonstrate the impact of individual risks on the overall build number. This helped TfL make informed decisions and have clarity on what their build figures represented.

Delivering accurate results at speed

At the end of the three-month period, the digital tool generated more than 5,000,000 cost estimates. This allowed us to assess multiple variations of each option at scale, not being limited to a single option per site. To deliver the same outputs manually, using traditional methods would have taken a team of 100 cost consultants more than ten years to complete. The custom parametric cost modelling tool allowed us to generate 83,000 estimates per day, compared to only two estimates, if done manually, creating efficiency.

By leveraging the optimisation-function of the mass-modelling software and the speed and accuracy of the parametric cost modelling, TfL received an independent integrated appraisal tool that produced one RIBA Stage 1 cost estimate every 50 milliseconds. This provided an incredible improvement on speed and accuracy and the results were also more efficient to produce than traditional methods.

For a client that owns multiple sites across the capital, we were able to deliver a digital tool that ticked all the boxes and overcame significant pressures on time.

For further information contact:

Cindy Curia
Associate Director