No change should be made in the direction of running on line 3 or in the current speed limits on any of the lines out to two miles six chains from Paddington Station unless and until the following have been done to the satisfaction of the HMRI, namely: (i) a risk assessment has demonstrated that the change can be implemented in safety, and, if this can be achieved only if certain measures are taken, what these measures are; and (ii) such measures have been implemented and shown to be effective. The risk assessment should take account of the following possible measures, inter alia: (i) the conversion of four-aspect to three-aspect signals; (ii) the addition of flank protection at SN109 and elsewhere if appropriate; (iii) the installation of standard, simple, non-distracting and consistent means of line identification; (iv) the alteration of the height, configuration and mounting of signals; and (v) the installation of an additional gantry to the east of Portobello Bridge for carrying Down signals previously carried on gantry 8. The risk assessment should be carried out by persons independent of Railtrack and in accordance with usual standards and the best available methods. It should take account of human factors which may affect the actions of drivers and signallers, and any risks which the carrying out of any of these measures might create (paras 7.127 and 7.128).