Route over the A30 at Chiverton Cross. Bridge option shown in red and the underpass option shown in green.
The at grade roundabout junction between the A30 and the A390 at Chiverton Cross has recently been replaced by a grade separated junction 750m north of the original one. Cyclists were originally offered two options; a bridge roughly on the line of the current A390 or an underpass 450metres north. The proposed underpass was 74m long, 4.0m wide and 2.7m high. Apparently the bridge option was dropped for project management reasons, rather than for reasons of cost or viability. The cycle campaign were concerned that the additional route length (950m) and lack of passive surveillance through the subway would deter potential cyclists from using the route.
Distance decay curves from the Propensity to Cycle Tool
Using distance decay curves, we calculated the probable fall in the number of cyclists. For a trip between St Agnes and Truro suppression would be around 5% and for shorter trips such as Chiverton Cross to Truro the suppression would be around 13%.
Data from Office for National Statistics
We also investigated the effect of trip suppression due to the ‘scary’ nature of the underpass. Around 60% of people (both men and women) would be deterred from using a subway such as this. In a rural areas there are few alternatives other than driving so measures that discourage cycling are not desirable.
The A30 project would be governed by the Design Manual for Roads and Bridges section CD195. This says, under safety, that “Cycle networks should not only improve cyclists’ and other road users’ safety, but also their feeling of how safe the environment is (their personal security). CD195 also says that where an overbridge is being introduced because a road severs an existing right of way, the overbridge shall be sited and aligned to minimise the diversion from the existing line of the cycle route. The proposed underpass goes against both these pieces of guidance plus some additional ones on design.
We built a case for the Cycle Campaign to argue that the bridge option should be reinstated. The bridge was subsequently re-instated in the scheme and has now been constructed. How much we contributed to this decision it is hard to say but it would be nice to think we pushed it over the tipping point. (Posted 05/03/25)
Another main road forming a barrier for active travel is the A14 at Hilton in Cambridgeshire and a river forms a barrier to cross at Arnside.