NATIONAL ASSEMBLY OF WALES ENTERPRISE AND LEARNING COMMITTEE
EVIDENCE IN SUPPORT OF CSAG PETITION
ANNEX A: CARNO STATION DEMAND FORECAST
1. Introduction
This document is an estimation of passenger usage of the new station with reference to existing usage of Caersws (6 miles to the East) by means of a comparison of weighted catchment populations and an estimate of passenger abstraction from Caersws. These figures will be used to estimate the net additional revenue of the two stations resulting from Carno re-opening.
2. Weighted catchment populations
The propensity of people to make train journeys from a station clearly decreases with increasing distance of their homes from the station. Work at the Institute of Transport Studies indicates that the “access time elasticity” is about -0.6, so that a 10% increase in access time results in a 6% reduction in the number of rail journeys per head of population. Assuming the propensity to use the station is constant for access times of less than 5 minutes, then we can define a “population weighting factor” as the number of journeys made per head of population for an access time in excess of 5 minutes divided by the number of journeys made per head of population where the access time is less than 5 minutes.
If passengers living more than five minutes walk away from the station drive to the station at a mean speed of 40 mph and take 3 minutes to park their cars, then the resulting variation of population weighting factor with distance from the station can be easily calculated.
Population weighting factors as described above have been applied to the populations of the villages surrounding Caersws for which Caersws is currently the nearest station, or the station of choice for journeys to the East (the predominant direction of outward journeys), in order to estimate the “weighted Caersws catchment population”. This is defined as the notional population living at Caersws itself that would generate the same number of journeys as the actual population spread over the whole catchment area. Based on the 2001 ward population figures for Caersws, Llanidloes, Llanidloes without, Llangurig, Trefeglwys, Carno, Llanbrynmair and Glantwymyn, the weighted Caersws catchment population comes to 6158 – much larger than the population of Caersws itself (1526). Note that in the case of Carno itself, the estimated 2007 ward population of 766 is used instead of the 2001 figure of 646 because at least 52 new houses have been built since 2001 (household size taken as 2.32 – the Powys average).
After the opening of Carno station, it is assumed that the populations of Llanbrynmair and Glantwymyn to the West of Carno and Cefn Coch to the North would fall into the Carno catchment. Applying new population weighting factors to the populations of these villages and a unity factor to the population of Carno results in a weighted Carno catchment population of 2165.
With the removal of the populations of Carno, Llanbrynmair and Glantwymyn from the Caersws catchment, its weighted catchment population reduces to 4903. Hence the new total weighted catchment population for Caersws and Carno is (4903 + 2165) = 7068 – ie 910 greater than the current Caersws figure of 6158.
The derivations of the weighted catchment populations is set out in Table 1 below.
TABLE 1: WEIGHTED CATCHMENT POPULATIONS
| Carno Population 2001 | 646 | No. of new houses | 52 | |||||
| Increase since 2001 | 120 | Household size | 2.32 | |||||
| Carno Population 2007 | 766 | |||||||
| Access time = Drive time + Parking time | ||||||||
| Access time elasticity | -0.6 | Mean driving speed, V | 40 | mph | ||||
| Mean time to drive to station in same village | 2 | min | Parking time | 3 | min | |||
| Time to drive to station from other settlements, Td = x(60/V) | ||||||||
Table 1.1 Caersws Catchment, weighted by distance decay factors
| Ward | Distance | Population | Drive time | Access | Access time | Weighted | |
| time, Ta | weighting | population | |||||
| x | Td | Td + Tp | wrt Caersws | ||||
| Caersws | 0 | 1526 | 2 | 5 | 1 | 1526 | |
| Llandinam | 3 | 942 | 4.5 | 7.5 | 0.78405268 | 738 | |
| Trefeglwys | 4 | 868 | 6 | 9 | 0.70280768 | 610 | |
| Carno | 6 | 750 | 9 | 12 | 0.59138902 | 443 | |
| Llanidloes | 8 | 2807 | 12 | 15 | 0.51728186 | 1452 | |
| Llanidloes without | 8 | 593 | 12 | 15 | 0.51728186 | 306 | |
| Llangurig | 13 | 670 | 19.5 | 22.5 | 0.40557623 | 271 | |
| Llanbrynmair | 11 | 958 | 16.5 | 19.5 | 0.44193789 | 423 | |
| Glantwymyn | 17 | 1106 | 25.5 | 28.5 | 0.35194523 | 389 | |
| Caersws catchment weighted population | 6158 | ||||||
Table 1.2 Carno Catchment, weighted by distance decay factors
| Ward | Distance | Population | Drive time | Access | Access time | Weighted | |
| time, Ta | weighting | population | |||||
| Td | Td + Tp | wrt Carno | |||||
| Carno | 0 | 766 | 2 | 5 | 1 | 766 | |
| Llanbrynmair | 5 | 942 | 7.5 | 10.5 | 0.64072021 | 603 | |
| Glantwymyn | 11 | 868 | 16.5 | 19.5 | 0.44193789 | 383 | |
| Cefn Coch | 7 | 750 | 10.5 | 13.5 | 0.55103824 | 413 | |
| Carno catchment weighted population | 2165 | ||||||
| Carno/Caersws existg | 0.351575 | ||||||
Table 1.3 Caersws Catchment after Carno re-opening, weighted by distance decay factors
| Ward | Distance | Population | Drive time | Access | Access time | Weighted | |
| time, Ta | weighting | population | |||||
| Td | Td + Tp | wrt Caersws | |||||
| Caersws | 0 | 1526 | 2 | 5 | 1 | 1526 | |
| Llandinam | 3 | 942 | 4.5 | 7.5 | 0.78405268 | 738 | |
| Trefeglwys | 4 | 868 | 6 | 9 | 0.70280768 | 610 | |
| Llanidloes | 8 | 2807 | 12 | 15 | 0.51728186 | 1452 | |
| Llanidloes without | 8 | 593 | 12 | 15 | 0.51728186 | 306 | |
| Llangurig | 13 | 670 | 19.5 | 22.5 | 0.40557623 | 271 | |
| Caersws catchment weighted population | 4903 | ||||||
| New Caersws + Carno weighted population | 7068 | ||||||
| Increase in weighted population catchment after Carno re-opening | 910 | ||||||
3. Carno station passenger forecast
The annual usage of Caersws station for 2005-6 in terms of the number of single journeys made, was 28257 passengers (Source: Station Usage 2005-6, Office of Rail Regulation). The passenger growth rate at Caersws, Newtown and Machynlleth over the last 3 years has been 6.2%, 4.0% and 4.2%. If passenger growth continues at the conservative value of 4.0%, the annual usage at Caersws in 2008-9 would be 31785 passengers.
If Carno station were to open in the mean time, the annual usage of Carno may be estimated by multiplying the latter figure by the ratio of weighted catchment populations giving 31785(2165/6158) = 11175 passengers.
4. Caersws passenger forecast following Carno re-opening
After the opening of Carno the Caersws weighted catchment population drops to 4903, so the Caersws annual usage drops to 31785(4903/6158) = 25307 – a reduction of 6478 passengers. Hence 11175 – 6478 = 4697 new single journeys are generated.
A.L.Burton 21.8.07