The 7 and 27 which approach the city centre from the Seven Dials direction will reach Imperial Arcade (in Dyke Road) then go via Queen's Road to Brighton Station and back towards Dyke Road.

The 5 and 5B in the Patcham and Hollingbury areas will reach as far as Preston Drove or Harrington Road only.  The 26 will reach as far as Fiveways.

Routes which approach the city centre along the Lewes Road will reach as far as Lewes Road Bus Garage.

The 50 will operate from Hollingdean to Lewes Road Sainsbury's.

In the Woodingdean area, the 2 will reach as far as the bottom of Freshfield Road and the 22 the bottom of Elm Grove.

A special service on the 23 will operate between the Universities, Queen's Park and the Marina, and this will be instead of the 25, 81 and 7 in these areas.

There is a major alteration on the Coast Road as this road is closed in both directions between Brighton and Rottingdean.  The 12 will operate from Eastbourne to Denton Corner as normal and then via the Lewes By Pass, Lewes Road, Elm Grove and Queen's Park Road to terminate at the bottom of Freshfield Road. 

The 14 will operate a special service between Peacehaven and Denton Corner where passengers can change onto a 12 to get to Brighton via the Lewes By Pass.  There will be Company Officials at Denton Corner to assist passengers.

In the Saltdean area, the 27 and 57 will operate via Falmer Road and Woodingdean to terminate at the bottom of Freshfield Road.  Falmer Road is likely to be very busy with traffic and the journeys are likely to be slow.

A further small alteration in the Hove area from 9am is that all buses heading west will be diverted via Selborne Road, Eaton Road and Blatchington Road instead of Church Road, and buses which would normally use New Church Road will be using Portland Road instead.

All the above diversions continue until 11am.

At 11am most roads in the city centre re-open and buses can go back to normal routes. 

The only diversions to continue after this time are the Coast Road, which remains closed until 1pm, and New Church Road which continues until 4pm.

There will be a lot of extra traffic so buses are likely to have difficulty keeping on time even when the roads re-open.

Full details of the revised timetables for the day are shown here

http://history.buses.co.uk/bustimes/marathon.htm