  We present the results from the optical component of a survey for damped
Lyman-alpha systems (DLAs) towards radio-loud quasars. Our quasar sample is
drawn from the Texas radio survey with the following primary selection
criteria: z_em > 2.4, optical magnitudes B < 22 and 365 MHz flux density S_365
> 400 mJy. We obtained spectra for a sample of 45 QSOs with the William
Herschel Telescope, Very Large Telescope and Gemini-North, resulting in a
survey redshift path Delta z = 38.79. We detect nine DLAs and one sub-DLA with
a mean absorption redshift <z> = 2.44. The DLA number density is n(z) =
0.23^{+0.11}_{-0.07}, in good agreement with the value derived for DLAs
detected in the Sloan Digital Sky Survey at this redshift. The DLA number
density of our sample is also in good agreement with optically-complete
radio-selected samples, supporting previous claims that n(z) is not
significantly affected by dust obscuration bias. We present N(HI) column
density determinations and metal line equivalent width measurements for all our
DLAs. The low frequency flux density selection criterion used for the quasar
sample implies that all absorbers will be suitable for follow-up absorption
spectroscopy in the redshifted HI 21 cm line. A following paper (Kanekar et
al.) will present HI 21 cm absorption studies of, and spin temperature
determinations for, our DLA sample.
