Virgin Marathon & Transport for London have both got detailed information on their sites although they slightly differ on times of road closures. Interestingly nothing on Council site.
The 1st picture below shows the route, 2nd TfL traffic impact analysis, 3rd & 4th more detailed road closures maps.
Vehicles on route will start to be removed 7am Sunday. Road closures start 6.30am but Virgin say vehicles can still move until 9.45am on Westferry Road if escorted. Access can re-open after 2pm but officially roads closed until 7pm.
It is not very clear but it does appear that Prestons roundabout is open (although a part is on the route) but your options are limited as Aspen Way & Cotton Street closed so you can only head east but I suggest you park outside of the area close to a DLR station if you have to use a car Sunday.
ISLE OF DOGS
There is no longer a dedicated vehicle lane along Westferry Road. Residents on the east and west side of Westferry Road will be able to exit onto Westferry Road and travel south to Manchester Road until 09:45 on Sunday 23 April. From 09:45 no vehicle movements will be possible until after 14:00.
Event motorcyclists, assisted by stewards, will be available to guide vehicles along Westferry Road when safe to do so before 09:45 or after 14:00 only. Residents will be unable to return to Westferry Road until the roads are fully reopened.
GREENWICH FOOT TUNNEL
The Greenwich Foot Tunnel will be open, however, it will be busy crossing south to north with queues anticipated. The Foot Tunnel will be closed north to south between 10:30-12:30. Alternative arrangements are in place on DLR services from Island Gardens.
The Marathon route through Canary Wharf is unchanged from 2016. Westferry Road and Heron Quays have ongoing building work and spectators should plan their visit. Shops, cafes, restaurants and transport links remain open
Vehicle removals across the whole route will start from 07:00 on Sunday 23 April.
Road closures in our area 06:30 until around 19:00 Sunday
East India Dock Tunnel
Limehouse Link Tunnel
Marsh Wall - I think there is emergency access only east side
Poplar High Street
Upper Thames Street
East Ferry & Aspen Way are not on the TfL list but it has to be closed as part of the route
Detailed road closure map