Police in Hertfordshire are suggesting people work from home to avoid disruption caused by a meeting of world leaders in Watford next month.
Heads of state will congregate at the Grove Hotel on Wednesday, 4 December as part of Nato's 70th anniversary summit.
Several roads and footpaths will be shut and the Grand Union Canal will be closed to both boats and pedestrians.
The force said it aimed to keep the impact to an "absolute minimum".
The meeting is part of the London anniversary summit which Nato said will be "an opportunity for leaders to address current and emerging security challenges".
Hertfordshire Constabulary has been liaising with the Metropolitan Police and other agencies to take measures to "minimise the impact on the community".
Closures will be in place for all, or some, of the time between 06:00 GMT on 2 December and 20:00 GMT on 4 December but there will be access for emergency and essential services.
Affected roads include Grove Mill Lane, Fir Tree Hill, Langleybury Lane and a section of Hempstead Road from the Hunton Bridge Roundabout to Courtlands Drive.
The canal and its towpath from Lock 74 at Lady Capels Wharf to Lock 76 at Cassiobury Park will also close.
Full details can be found on Hertfordshire Constabulary's dedicated web page.
The flying and use of drone equipment will also be prohibited.
Ch Insp Matt Phillips said: "Whilst it is inevitable that such a high-profile event will cause some disruption, we aim to ensure that any impact on the local residents and businesses is kept to an absolute minimum and are working closely with our partners to achieve this.
"Increased traffic congestion is anticipated therefore residents and visitors are asked to consider their plans, such as finding alternative means of transport or working from home."