According to the amended Environmental Statement (Addendum 2, summer 2010, ES2 ) submitted by BAA to the Department for Transport, it is theoretically possible that Airtrack might will close Egham’s level crossings for less than 35 minutes per hour –
Thorpe Road Level Crossing could be be closed for only 34 minutes per hour
Egham Station Level Crossing might be closed for only 30 minutes per hour
Pooley Green Level Crossing might be closed for only 33 minutes an hour
That’s assuming that
Network Rail will re-timetable the entire southwest of London, so that east and west-bound trains pass each other EXACTLY at Pooley Green

All trains run exactly according to schedule, with no delays, no extra trains, no freight trains.

Barriers will be re-opened if if the gap between trains will allow 20 seconds open time. But “The sample of observed time parameters from the HAL video surveys, when averaged, is generally representative of normal operations. It must be appreciated, however, that the sequence of barrier closure is initiated by the signalman in the course of his normal signalling duties and can be subject to variations.” Level Crossings and Egham

Egham: has a population of about 12,000. About half live in Egham Town and half in Egham Hythe. Another 10,000 live in Englefield Green, including several thousand at Royal Holloway College.
The railway line cuts through the town with most of Egham Town to the north of the line and most of Egham Hythe to the south. We currently have about 8 train an hour, more in peak time.

Level Crossings
Egham has 4 level crossings. From west to east:
Prune Hill has half-barrier crossings which are down for less than a minute per train. The road immediately after is very narrow and and quite steep and curving. Not suitable for heavy traffic.

Egham Station
Egham Station has full barrier crossing gates across Station Road, which are down about 3 minutes per train. There is a pedestrian footbridge which pre-dates disability legislation, with steps rather than a ramp. There is, however no alternative and it could be argued that it is in breach of the Disability Discrimination Act as a result. It is expected to be open for 25 minutes per hour on average if Airtrack is built and the trains run on time.
Pooley Green has (since about 2003) full barrier crossing gates across Vicarage Road, down for about 3 minutes per train. No footbridge. It is expected to be open 21 minutes per hour average under Airtrack proposals. The level crossing is very close to the M25, which elevated at this point. On one side of the crossing the road bends sharply then goes under the motorway, on the other side there is a left turn onto Pooley Green Road (traffic from Pooley Green Road has to turn right onto Vicarage Road to reach Egham town centre, M25, and A30.
Thorpe Road (described by Airtrack as Thorpe Road, Staines) has full barriers. Is expected to be open average 27 minutes per hour if Airtrack proceeds. Road sort-of ramps up towards railway line, but houses close by. Is quite close to river and the roundabout leading the Causeway and to Staines Bridge, so after queuing at the crossing you hit a another queue for the roundabout. Somewhere nearby is reputed to be a small residential road where the railway can be crossed without using level crossing: I don’t know if it road goes over or under the line, but I’m told it won’t do for fire engines. (and in Nov 2009 Surrey County Council is heard to be planning to close it off).
Alternative routes from Pooley Green to Egham avoiding level crossings: (or the other way for fire engines from Egham Fire Station to Pooley Green)

1) Small residential road near Thorpe Road crossing, (as above): I haven’t tried out this one.

2) Vicarage Road, Thorpe Lea Road, Thorpe Bypass, Green Road, Virginia Water, (cross the railway at Virginia Water Station), Christchurch Road, then either turn onto A30 at Virginia Water lake or via Callow Hill, into Bakeham Lane and right onto A30 at Royal Holloway, down Egham Hill, into High Street.

Other towns:
There are 11 other level crossings in all which will be affected by Airtrack. Only one of the Wokingham ones will see as great a deterioration in down times as our three. But there are several in Richmond that are already so bad that even a small increase in the number of trains will leave them nearly as badly off as we are.