Supt. Trevor Roe - "This is an attempted murder investigation"
Police have increased patrols along the A12 and bridges and forensic examinations of the items recovered and the bridges is continuing.
Supt Trevor Roe said: "We have had a fantastic response from the public so far but my appeal for information continues.
"Essex Police's focus is on the events on the same day in December but as part of that investigation we are looking back at incidents in previous years and looking at any possible links.
"We are conducting reassurance patrols across the 39 bridges on the A12 that stretch from Ipswich to the M25.
"The sooner these individuals are brought to justice the better." #A12 #bridge #Chelmsford #concrete #Essex #Police #Superintendent