Railway Tunnel SubSurface Inspection (RTSSI) is essential for targeted structural maintenance. ‘Effective’ detection, localisation and characterisation of fully concealed features (i.e., assets, defects) is the primary challenge faced by RTSSI engineers, particularly in historic masonry tunnels. Clear conveyance and communication of gathered information to end-users poses the less frequently considered secondary challenge. The purpose of this review is to establish the current state of the art in RTSSI data acquisition and information conveyance schemes, in turn formalising exactly what constitutes an ‘effective’ RTSSI visualisation framework. From this knowledge gaps, trends in leading RTSSI research and opportunities for future development are explored. Literary analysis of over 300 resources (identified using the 360-degree search method) informs data acquisition system operation principles, common strengths and limitations, alongside leading studies and commercial tools. Similar rigor is adopted to appraise leading information conveyance schemes. This provides a comprehensive whilst critical review of present research and future development opportunities within the field. This review highlights common shortcomings shared by multiple methods for RTSSI, which are used to formulate robust criteria for a contextually ‘effective’ visualisation framework. Although no current process is deemed fully effective; a feasible hybridised framework capable of meeting all stipulated criteria is proposed based on identified future research avenues. Scope for novel analysis of helical point cloud subsurface datasets obtained by a new rotating ground penetrating radar antenna is of notable interest.

It is of great importance to improve the spatial resolution and sensitivity of magnetic flux leakage (MFL) sensors for small cracks characterisation on pipelines. To solve these problems, a novel pulsed magnetic flux leakage (PMFL) method, using magnetic head (MH) and a side placement of tunnelling magnetoresistance (TMR) is proposed. Two symmetrically inclined magnetic cores with a tiny air gap opening form a small detection region, making PMFL focus in that area. The side placement of the TMR ensures a reduction of noise and lift-off influence. A series of comparative tests with different kinds of artificial and natural cracks have been used to verify the high spatial resolution and sensitivity of the proposed method. The higher signal-to-noise ratio (SNR) and sensitivity of the side placement TMR were verified by two-dimensional (2D) and three-dimensional (3D) magnetic maps corresponding to the natural crack. The SNR and sensitivity of the side placement of TMR is greater than that of the under placement by an average of 41% and 160% respectively.

This paper supplements two previous papers written by the authors and addresses three issues arising from those papers. The three issues are follows: (1) the robustness of a crashworthy design in scenarios different from the design conditions, (2) the correlation of structural crashworthiness with passenger safety and (3) behaviour characterisation of vehicle materials in train collisions. The investigation of these issues provides an increased understanding of the research conclusions gained from a number of varied conditions, and targeting the development requirements in these three areas will promote crashworthiness applications in rail vehicles.

To meet the various demands for bus platforms tailored for the emerging new power sources, an adaptive design method is proposed for a bus chassis development using a design structure matrix. The structural feature parameters of the product modules are extracted and the corresponding design structure matrix is established to analyze structural correlations between modules. An adaptive design method process model is constructed following quantification of the design structure matrix. A digital matrix of the module interface is then built to characterize integration and interchangeability of functional modules. Reconfiguration of modules is conducted using the parent-child relationship premise so that the interface matrixes are well integrated. The adaptability of these products is subsequently improved by sharing dominant modules and replacement of local modules. Finally, the implementation of the proposed methodology is illustrated for a current bus chassis.

Lift-off has a significant impact on defect discrimination and qualification. Estimating lift-off and evaluating defects is a critical issue for eddy current testing (ECT). In this paper, a novel sensor that separates lift-off and defects is proposed. This uses common-mode and differential-mode coils with a dual signal conditioning circuit. Specifically, it comprises two hollow rectangular excitation coils located on the first and third layers of the PCB, serving as the two arms of an AC bridge circuit. The output from the bridge signal is used for lift-off estimation since the co-axial configuration and small coil fill ratio make it specifically sensitive to lift-off variation. The other pair of rectangular receiver coils are situated on the second and third layers and placed in the middle of the hollow transmitter. This forms a transformer with excitation coils and is only sensitive to defects. The signals from these two complementary outputs allow lift-off to be used as auxiliary information for defect discrimination. Simulations and experiments were carried out to validate the method. This proves that a combination of coil configurations with different signal conditioning techniques can be employed for separating multiple parameters.