Transport Accessibility Executive Summary

8/8/2019 Transport Accessibility Executive Summary

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Transport Accessibility

Case for London Technical Report 1

Executive Summary


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Colin Buchanan and Partners Accessibility

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Executive Summary

Introduction

This study investigated the relationship between accessibility anddensity of both population and employment. It studied that relationshipat two levels:

At a London-wide level where accessibility to/from each individualward (782) was measured in terms of rail only; and

At a local level where accessibility was measured for all publictransport (including buses).

The accessibility analysis was undertaken using CBPs ABRA modelwhich represents all rail services and train station locations in London.The model also includes all bus services and stop locations in South-East London, from where the case studies were drawn. Accessibility ismeasured in generalised time with weightings applied to walk time andwaiting time. It excludes fares.

A review was also undertaken of the extent to which teleworking couldalter transport demand in the future.

London-wide Analysis

The London-wide analysis determined the travel time required to accessall other wards from each individual ward. That information could thenbe categorised and linked to data on population and employmentdensity, enabling us to quantify:

The population within X minutes (generalised time) of each ward The number of jobs within X minutes (generalised time) of each

ward

Figure 1 shows that average accessibilities vary by location.

Accessibility is greater in Central London (LUL zone 1) than it is in InnerLondon (between Zone 1 and the North/South Circular) and OuterLondon. The number of people able to access an average ward within60 minutes of generalised time is roughly 4.8 million for a ward in thecentral area, 3.2 million within the inner area and 1.5 million in outerLondon.


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Figure 1: Accessibility by population to London

CBP examined the relationship between accessibility (i.e. the number ofpeople able to access a given within ward within X minutes) and thedensity of employment within that ward. The analysis included a numberof other variables (highway accessibility, Central/Inner/Outerclassification) and was carried out for a range of generalised time limits

(30, 45, 60 and 90 minutes). The relationship is shown in Figure 2 using45 minutes as the time limit.

Figure 2: Accessibility and employment density in London wards


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Figure 2 shows that there is clearly a correlation between accessibilityand employment density (as we would expect), but also:

At low levels of rail accessibility, employment density increases withrespect to accessibility at a relatively low rate. This suggests thatthere may be a base level of employment density, and that these

jobs are typically accessed by car, bus or walk. There is a kink at high levels of accessibility. At that point, further

increases in accessibility are correlated with much higher increasesin employment density. These high levels of employment density aredependent on rail access.

The study also investigated the relationship between population density

and accessibility to employment (i.e the number of jobs that people canaccess from a ward within X minutes). This analysis was undertaken ina similar manner and is shown in Figure 3.

Figure 3: Accessibility and population density in London wards

Examining the relationship between population density and accessibility

also produced a statistically significant relationship. Population densityappears to increase in line with accessibility only up to a certain point,beyond that point population density fell despite further rises inaccessibility. The most likely reason for this is that at very high levels ofaccessibility residential development is squeezed out by commercialdevelopment.

A final test looked at the relationship between house prices andaccessibility, shown in Figure 4. There is clearly a positive link between


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accessibility and house price, although the explanatory power of theregression analysis is less than found for population density and

employment density. This suggests that there are many other factorsthat contribute to house prices, but the link between house prices andaccessibility is nonetheless important.

Figure 4: Accessibility and house prices in London wards

Case Studies

In order to examine whether the London-wide analysis could be used toinform decisions about transport improvements at a more local level,CBP examined a number of case studies. The case studies comprised:

Two high density employment areas, the City and Isle of Dogs Two regional centres, Lewisham and Bromley Two local centres, Beckenham and Crystal Palace

For the case studies, more information was collected on employmenttypes, planning policies, development potential (measured by planningpermissions granted) and historic and expected growth in population

and employment.

It proved difficult to draw many firm conclusions from the case studies.Those that could be drawn were:

If the Isle of Dogs is to achieve the growth forecast in the LondonPlan then either accessibility must be improved or it would representone of the largest outliers from the accessibility curve

Lewisham has potential for higher employment densities than existat present and employment density in Lewisham is roughly at the


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level where employment density rises more steeply with increases inaccessibility. It may therefore be a location where improving

accessibility would have a disproportionate impact on employment.

Perhaps the biggest issue that is highlighted by the case studies is thatusing ward level data is inadequate. Areas are too large andaccessibility varies too much within wards. In the City, where all thewards have similar characteristics, this is not a problem. However, in theregional and local centres, there are large differences both between andwithin individual wards.

Information and Communication Technology

If information and communication technology (ICT) affects the demandfor transport, then there are important implications for the need for publictransport accessibility. Although some studies have found thatteleworking can improve productivity and reduce the demand for travel,evidence suggests this is not typical. In most cases, a number ofpractical issues restrict the implementation of teleworking, but it is theissue of face-to-face contact that is most important. The overwhelmingissue preventing teleworking from replacing commuting (especially inthe central business districts of world cities) is that teleworking cannotsubstitute for brainstorming, creativity, learning on the job and above all,teamwork.

In many cases, ICT may generate more (or longer) trips than it replaces,but in Central London the transport network is at or near capacity duringthe peak period, and as a result, any potential for reducing demandduring that time is the focus of investigation. However, the type ofemployment that exists in Central London is not conducive toteleworking. Businesses in Central London pay premium rents for theirlocations, and they do so because there are advantages of havingemployees together in the central area. CBP examined the potentialreduction in commuting that could result from teleworking using theassumption that Central London workers could work a maximum of two

days per week at home. CBP calculated the number of commuters onLondon Underground (LUL) who are not engaged in client-facing work,who are sufficiently senior, who do not (at present) telework at all, andwho live sufficiently far from work to make teleworking attractive. Theresult is that the maximum possible reduction in AM peak trips fromteleworking is 9%, well below the forecast increases in central areaemployment in the London plan.


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Conclusions

The study has found statistically significant relationships betweenaccessibility and employment density, accessibility and populationdensity and accessibility and property prices. The greatest explanatorypower is found in the relationship between accessibility and employmentdensity.

The case studies did not find a simple method for linking accessibilityimprovements to potential generation of private sector investment. Thelink between accessibility and employment density offers some insightsinto London-wide trends, but in the brief analysis undertaken was unableto provide much help at a ward level. It is possible that the analysis

would be more useful if undertaken at an individual site level.

Analysis of the impact of ICT suggests that increasing will notsignificantly affect the need for expenditure on public transport capacityto the central area.

Transport Accessibility Executive Summary

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