29-May-2013

Draft Environmental Statement -
Doing the Maths…

The spreadsheet collects together information for construction sites in the Chilterns - from tables 1 & 12, for CF (Community Forum ) areas 7 to 10 – Colne Valley to Wendover. This gives some idea of the impact of HS2 construction on the AoNB.

Workers

The grand total for ‘Average Working Day’ workers over the 25 construction compounds is 1180, agreeing reasonably well with a total of 1125 LGV ( ie Car or Van ) trips each day. While not all compounds will be active at the same time,  the peak number of workers is in some cases double the average, so a workforce of over 1000 for 3 to 4 years seems likely.

Construction Traffic

All traffic from CF areas 8,9 & 10 will use the A413 at some point, generating 310 HGV trips ( in each direction ) every day – or one every 2m 20sec if spread evenly over a 12 hr day ; one lorry every 1.5 miles, if they can manage 40mph in the resulting congestion.  Nearly half of these trips ( 130/day) will also use the B485 or Frith Hill route up to the South Heath tunnel sites
In addition to the HGVs, there are 835 LGV trips/day on the A413, presumably peaked at the beginning and end of the working day.  With the recommended separation of 40 yards ( at 40mph ) that would produce a queue 19 miles long – if all approach from the same direction.

Costings

Assuming the cost of construction is approximately proportional to the number of man years required, the estimated numbers of workers in the compounds, and the duration of use, gives a rough  estimate of construction costs. For example, the South Heath tunnel compounds will provide 3.5*100 + 4*25 = 450 man years of labour.  The peak number of workers at the Chiltern Tunnel main compound ( in the Colne Valley ) is 275, and the extra tunnelling time to extend the bored tunnel beyond Frith Hiill is one year, which suggests the cut & cover tunnel may cost around 50% more than an extension of the main Chilterns Tunnel.