Plans for a Shrek-themed attraction at County Hall are due to be approved this week despite fears of "unacceptable" overcrowding on the South Bank riverside walkway.
However, planning officers have warned that "the Queen's Walk in the vicinity of County Hall is susceptible to crowding, and the cumulative impact of the various attractions located there could result in an unacceptable level of comfort for pedestrians".
In their advice to councillors, Lambeth Council transport planning officers note that a pedestrian survey carried out this section of the Thames Path in 2007 found that around 5,000 people walked along the Queen's Walk each hour on an average summer afternoon between 2pm and 6pm.
Visitor numbers are thought to have increased by nearly one fifth since 2007.
The report continues: "Assuming 5,950 people [per hour] (based on a 19 per cent increase in flows) walk past the entrance ... to the new attraction on a section of the Queen's Walk which measures 7.6m, the pedestrian comfort level [PCL] is found to be 'B', which is classed as 'acceptable' by TfL for tourist attractions.
"However, this does not take into account the additional visitor numbers associated with the London Dungeon (527 during the peak hour), or the new attraction (400 during the peak hour), or any area of static activity associated with pedestrians pausing to look at views / take photographs etc.
"Taking into account an area of 'static activity' generated by a depth of two people for example would reduce the clear footway from 7.6m to 6.2m (The depth of a person is 0.45m plus a buffer of 0.5m resulting in static activity measuring 1.2m).
"Taking these figures into account results in a PCL of C which is considered 'unacceptable' in an area of tourist activity."
Council officers have recommended that Merlin Entertainments should be required to fund ongoing monitoring of pedestrian comfort levels.
A final decision will be made by Lambeth councillors on Tuesday 1 April.
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